Document Attachments

One of my clients had asked me to add Document Attachments to Bank Deposits. Thinking this was a quick and easy one I added the factbox, set the link, and went on with my day. When my client said they see all attachments for all records, I realized it is a little more involved. It took some time to figure out how it actually works, and this post explains the whole thing, including how to get document attachments through the posting process.

How Does it Really Work?

The reason why it’s not so simple is because the Document Attachment works with RecRef instead of a hardcoded table relationship. Take a look at the Document Attachment table (table number 1173 in the base app) for the field definitions. I’ll focus on single field PK records in this post, so tables where a single Code20 field has the unique identifier of the record. The more complex compound PK works the same, you just need to set more fields.

Standard BC has a limited number of tables that have document attachment capabilities. If you want to add another table, whether a custom table or another standard table, you will need to subscribe to some events to make that work. Let’s first look at how standard document attachments work.

Open Document Attachments

Let’s take a look at the Customer Card page in standard BC. The “Attachments” action has the following OnAction trigger code:

trigger OnAction()
    DocumentAttachmentDetails: Page "Document Attachment Details";
    RecRef: RecordRef;

The “Document Attachment Details” page is where the magic happens. If you drill down into the ‘OpenForRecRef’ function, you will see that it takes a RecRef variable (which in this example is looking at the current Customer record) and sets filter on the table ID of the RecRef and the value of the PK field of the record itself. This is the function that defines all the tables in the standard BC app that have Document Attachments.

The important thing in this function is the call to OnAfterOpenForRecRef, which is an event publisher that we will subscribe to later. This event gives you the capability to set a filter to any table. Note that this is just a filter on a page. All that this does is make sure that you only see the document attachments for this particular record.

The Document Attachments Factbox

Another way to give the user access to the document attachments is the “Document Attachment Factbox” that you can see in the factboxes area. In the standard app on the Customer Card, the SubPageLink property links the “Table ID” field to a hardcoded value 18 (which is Customer table’s object id). If you want to create your own link, you should use the table name instead of its number. So we will be linking to the “Bank Deposit Header” table, so our constant value will be Database::”Bank Deposit Header”.

Take a look at the OnDrillDown trigger of the NumberOfRecords field in the factbox. It first sets up the RecRef, which is again hardcoded for the standard range of tables that have document attachments. Then it executes the same logic on the Document Attachment Details page as the action mentioned above.

Note the OnBeforeDrillDown function call in the ‘else’ leg of the ‘case’ statement. This is the event that you need to subscribe to in order to properly filter the document attachments for non-standard tables.

What is important to understand about this particular factbox is that records are not entered directly into the factbox. You have to click an action that adds the record, and as a result the “No.” field in the factbox is NOT populated by the page link.

Creating New Document Attachments

So far we’ve only looked at how to display the proper document attachments to the user. What’s left is how BC actually stores these records. The part that is tricky is not about getting the file itself, but how BC gets the value from the RecRef. The function that stores the values from the RecRef into the document attachment is called InitFieldsFromRecRef. You can see that this function again goes through all of the same hard coded standard BC tables that we’ve seen before, and it provides an event publisher called OnAfterInitFieldsFromRecRef that you can use for additional tables.

Document Attachments for Additional Tables

Alright, now let’s put it all together for a new table. I recently added this for Bank Deposits for a client of mine, so I’ll use the same table to illustrate. I’ll focus on the new ‘Bank Deposit Header’ and its Posted sibling. The new implementation of bank deposits can be found in the “_Exclude_Bank Deposits” app that is part of standard BC.

To get started, create a page extension for the Bank Deposit and the Posted Bank Deposit pages, and add the Document Attachment factbox. You can copy this from the Customer Card and change the links appropriately. Note that the records that you will see when you drill down into the details are filtered on the table but not by the PK value of the record that you are looking at. In other words, just adding this factbox will only give you a list of all the Document Attachments that are linked to ALL (Posted) Bank Deposits.

Finally, create a new codeunit, I called mine ‘DocAttachmentSubs’.

Filter the Details

First, we need to make sure that the “Document Attachment Details” page is filtered on the correct Bank Deposit number. For this we subscribe to the OnAfterOpenForRecRef event.

[EventSubscriber(ObjectType::Page, Page::"Document Attachment Details", 'OnAfterOpenForRecRef', '', true, true)]
local procedure DocAttDetailsPageOnAfterOpenForRecRef(var DocumentAttachment: Record "Document Attachment"; var RecRef: RecordRef)
    MyFieldRef: FieldRef;
    RecNo: Code[20];
    if RecRef.Number in [Database::"Bank Deposit Header", Database::"Posted Bank Deposit Header"] then begin
        MyFieldRef := RecRef.Field(1); // field 1 is the "No." field in both tables
        RecNo := MyFieldRef.Value();
        DocumentAttachment.SetRange("No.", RecNo);

Filter the Factbox

Next, we need to make sure that the details are filtered properly when the user clicks the DrillDown from the document attachment factbox. For this we subscribe to the OnBeforeDrillDown event in the factbox.

[EventSubscriber(ObjectType::Page, Page::"Document Attachment Factbox", 'OnBeforeDrillDown', '', true, true)]
local procedure DocAttFactboxOnBeforeDrillDown(DocumentAttachment: Record "Document Attachment"; var RecRef: RecordRef)
    BankDepositHeader: Record "Bank Deposit Header";
    PostedBankDepositHeader: Record "Posted Bank Deposit Header";
    case DocumentAttachment."Table ID" of
        Database::"Bank Deposit Header":
                RecRef.Open(Database::"Bank Deposit Header");
                if BankDepositHeader.Get(DocumentAttachment."No.") then
        Database::"Posted Bank Deposit Header":
                RecRef.Open(Database::"Posted Bank Deposit Header");
                if PostedBankDepositHeader.Get(DocumentAttachment."No.") then

So now when the user clicks the drilldown, BC will set the RecRef to look at the (Posted) Bank Deposit, which is then sent into the details page, which then knows how to properly filter.

Set the Right Link

The last thing we need is to make sure that new document attachments have the (Posted) Bank Deposit number, by subscribing to the OnAfterInitFieldsFromRecRef event of the Document Attachment table itself.

[EventSubscriber(ObjectType::Table, Database::"Document Attachment", 'OnAfterInitFieldsFromRecRef', '', true, true)]
local procedure DocAttTableOnAfterInitFieldsFromRecRef(var DocumentAttachment: Record "Document Attachment"; var RecRef: RecordRef)
    MyFieldRef: FieldRef;
    RecNo: Code[20];
    if RecRef.Number in [Database::"Bank Deposit Header", Database::"Posted Bank Deposit Header"] then begin
        MyFieldRef := RecRef.Field(1); // field 1 is the "No." field in both tables
        RecNo := MyFieldRef.Value();
        DocumentAttachment.Validate("No.", RecNo);

You should now be able to create new document attachments for unposted and posted bank deposits. All that’s left is to get document attachments to flow through the posting process.


Document Attachments are not intrinsically difficult. In the end they are just records in the database. The records are identified by their Table ID and their PK values. For Bank Deposits the PK is a single Code20 field, and there are two versions of the table. All we need to do is write a little loopyloopy that reads the records for the unposted record, copy it into the posted record, and get rid of the old ones. Would be cool to just change the records, but since both the Table ID and the record identifier are all part of the PK, you can’t do a ‘Rename’ because then you’d have to sit there and click confirmations all day long.

For Bank Deposits, you can use the OnAfterBankDepositPost event in the “Bank Deposit-Post” codeunit.

[EventSubscriber(ObjectType::Codeunit, Codeunit::"Bank Deposit-Post", 'OnAfterBankDepositPost', '', true, true)]
local procedure BankDepositPostOnAfterBankDepositPost(BankDepositHeader: Record "Bank Deposit Header"; var PostedBankDepositHeader: Record "Posted Bank Deposit Header")
    MoveAttachmentsToPostedDeposit(Database::"Bank Deposit Header", BankDepositHeader."No.",
                                    Database::"Posted Bank Deposit Header", PostedBankDepositHeader."No.");

local procedure MoveAttachmentsToPostedDeposit(FromTableId: Integer; FromNo: Code[20]; ToTableId: Integer; ToNo: Code[20])
    FromDocumentAttachment: Record "Document Attachment";
    ToDocumentAttachment: Record "Document Attachment";
    FromDocumentAttachment.SetRange("Table ID", FromTableId);
    FromDocumentAttachment.SetRange("No.", FromNo);

    if FromDocumentAttachment.FindSet() then begin
            ToDocumentAttachment.Validate("Table ID", ToTableId);
            ToDocumentAttachment.Validate("No.", ToNo);
        until FromDocumentAttachment.Next() = 0;

I have this in a separate function because I also had to make it work for the old Deposit implementation. You could totally combine this into a single event subscriber.

I’m thinking about creating a video about this topic. Let me know if this was useful in the comments and if you’d like to see the video.

Repair Companion Tables

One of my clients has been seeing these weird data issues when migrating databases to the cloud. The most important purpose of this post is to point out a handy data tool that is buried deep in the application, read on to learn what I am talking about.

The problems that my client is experiencing mostly have to do with various ways in which they get data from OnPrem to the cloud. One way is to use the cloud migration tools, another is configuration packages. In addition to using different tools, it feels like there may be some issues with the BC platform’s capability to properly manage data in table extensions. I’ll tell you why I think that.

Missing Data

The first indication was a problem where invoices were migrated into the cloud. The migration process seems to have completed, and the posted invoice list shows a list of invoices. The weird part is that when you try to open an invoice, it shows an empty invoice page. Click ‘View Table’ from the page inspector, and you get nothing, a list of zero records even though the posted invoice list shows the records. Go to the admin center to look at the capacity, it tells us there are like 1154 invoices but when you drill down into the number you get another empty list.

This feels very familiar to me, very much like when a lot of companies tried to migrate straight into SQL Server and we would see null field values. As we all know, BC can’t handle null values. Instead of getting an error saying ‘there are null values!! I don’t know what to do!!’ you get weird behavior like empty lists for tables that you know have plenty of records.

Solving The Problem

With the explosion of moving functionality into separate apps, I had a feeling that the problem had something to do with table extensions (which as you know have added fields in what is called ‘Companion Tables’). I had posted the question on Twitter and there were suggestions to uninstall and re-install apps. This worked sometimes but not all the time.

The original Tweet asking for help on this issue

What it feels like to me is that either there are null values in records, or maybe records are missing in companion tables altogether. We don’t have access to Azure SQL so there is no way for me to actually prove that there is an issue with table extensions. SOMETHING is wrong here though, and for the longest time the only way that I thought we could fix it was to uninstall/re-install apps until the issue was fixed. The reason why this works is that each time you install an app, it will update the schema and make sure that data integrity remains intact. In other words, it will make sure that all records in the main tables have corresponding records in all companion tables.

And then I became aware of a VERY handy little tool. This tool is not available when you are working in local containers, but when you are in a cloud tenant, you will have access to it. I’m talking about the “Repair Companion Table Records” process in the “Cloud Migration Management” page.

The tool will go through all tables that have table extensions, and make sure that each record in extended tables has a corresponding record in each companion table. I still can’t prove my theory but I do know that running this process fixed the problem for my client.

Free Training

There are SO MANY resources to learn about BC and AL development out there. Some of the best of them are totally For Freeeee!! As I always like to point out: free is in everybody’s budget. Today I noticed a video that popped up in my YouTube timeline. It was a video that I had recorded a few years ago, and I noticed that it had more than 30K views! Just an unreal number, and I want to share the story about these videos.

It Starts…

Back in 2018 I was one of the owners of a well-known company (I’m gonna keep the name out of this post for personal reasons). We were working closely with Microsoft on the cutting edge of all the new technologies. We had developed the material for a number of workshops, and we all traveled to a bunch of different places all over the world to teach NAV people the intricacies of the new technology stack, new processes in the channel, and the philosophy that would become the path that we are now all traveling. Chances are that if you attended any event that was organized or sponsored by Microsoft, you have attended one of our workshops.

At some point, we were stretched quite thin. There were more requests for these workshops than we had staff to hold them. Microsoft then came up with the brilliant idea to record our workshops and create a series of videos that would be made available on PartnerSource.

Creating Content

We created a Very. Long. List. of topics, and the word came in from Microsoft: start creating content! The task of actually creating the videos fell to me, because of my demeaner during in-person classes and my pleasant baritone voice *ahem*. The truth is that most of my co-owners thought this would be a terribly tedious task, and I was the only one that was actually excited to record all of this material. Also, I had a LOT to learn and this was a perfect opportunity to do just that. As far as I’m concerned, this was by far the coolest project I had ever taken on in my professional career. It was explained to me that Microsoft would provide the content, and all that I had to do was record the videos.

It would take a whole series of posts to tell the stories of creating the content, so let me just summarize. Despite assurances from one of my co-owners, nobody at Microsoft knew about the expectation that they would provide ANY sort of content, other than meeting with me to briefly discuss the outline of the content and providing answers to questions. For a number of topics we had some content from short presentations at various events, but none of it was nearly good enough to make it into the videos. As it turned out, I had to create most of the material from scratch. A LOT of willing and eager Microsoft people spent a very limited time with me to first explain the basics and then go over the results of my material before I recorded it.

Let me just make one thing very clear. I enjoyed every single minute of the process of creating and recording the material. It was an absolute joy to work with every single person from the BC team, many of whom had to endure completely ignorant questions from me. I am super grateful to have had the opportunity to work with each and every one of them. I could not have done any of this without their help.

Over the course of 6-7 months, I created more than 20 hours of videos. The topics range from a condensed version of our 2-day AL Development workshop, to videos about how to get your app into AppSource, to automated testing, to source code management. Picked up a bunch of skills that I still benefit from today. It really was one of the best projects of my career.

The Academy That Never Was

The initial idea was that Microsoft would create some sort of ‘academy’ that would be accessible in PartnerSource. Partners would pay a fee for to provide training to their staff, of which our company would receive a percentage. All good with us, because there were BIG plans for the ISV Development Center, so we didn’t think we would have much more time to do in-person workshops anymore anyway.

Soon it became clear that this academy was not going to happen. There were calls from partners that they would not want to pay for this, since they never had to pay to attend any in-person events. At some point about half the videos were done, most of the material for the rest was ready to record, and the question was to continue recording or to stop the project.

There was talk of putting the videos on PartnerSource but not behind a paywall, which just made no sense to me at all. Most developers that I know don’t even have access to PartnerSource, so they would never even see it. Besides, if you are going to provide this content for free, why not just put all of it on YouTube? Just upload it to the public and let anyone that wants to learn all the skills that you need to make it as an AL developer. Once I heard that the content was going to be made available for free, I went all in and talked to anyone that wanted to listen that it should be made available publicly.

To make a long story short, they did end up putting the videos on YouTube (they are all in a single playlist that you can access here).

Unexpected Impact

It’s been almost four years since I created these videos. Still today, every once in a while, videos from this playlist show up in my YouTube timeline, like today. It just struck me that this video had 30K (thirty THOUSAND!!!) views. I was just so surprised about how many people have watched videos that I created. Thinking about all the people that have learned these skills, partly as a result of listening to me explain them. It just makes my head spin.

There are two things about these videos that I take full credit for. First, since I was responsible for the content, I had decided that I wanted to make proper full-length videos. Not condensed summary videos with the high level view of the topic, but deep down detailed videos with ALL the information that you need to execute on that topic.

The second things is getting the content into YouTube. The project manager told me that my relentless lobbying to every person in the BC team was a key factor in getting them to put these videos on YouTube. I was paid to create the videos but getting them to YouTube was totally done with a community spirit. This is by far the most impactful contribution I have ever made to the BC community, one that I am extremely proud of.

Microsoft the ISV

Microsoft published their new Shopify connector today. It’s great to see them invest resources into what is hopefully the gold standard of integrating with these external services. However, I have serious doubts about whether this is such a good idea.

ISV Partner Channel

In the runup to having BC in the cloud, the story was that the partner channel should refocus their efforts into becoming ISV’s. Rather than one-time bespoke systems for individual customers, they want the partner channel to create extensions that could be used by the masses.

This was (is?) a logical continuation of their story of verticalization that we had heard throughout the past two decades. In itself nothing that I don’t agree with. I too think that having re-usable extensions in a marketplace is a solid way to go. Microsoft’s argument was that they need to focus on the base product, a core set of functionalities. The partner channel would then be free to add functionality, to extend the base product.

There’s Just a Tiny Thing…

One thing that caught my ear was a statement that said that Microsoft does not want to provide specific, industry focused expertise. They said they have no interest to build integrations with external systems. Rather than having Microsoft provide integrations or other specialized functionalities, they would leave this up to the partner channel. There could be an ACME Rockets integration created and supported by an ISV, or even by ACME themselves.

Great soundbite showing great potential, and it sold well. Many partners listened to Microsoft and started creating lists of functionalities that they have know-how for. Many VARs dove right into their inventory of “add-ons” with the intent to turn those around into the next AppSource apps.

I know personally of three separate partners that have invested a lot of time and money into developing Shopify integrations. All three of those partners are LIVID with Microsoft today. The promise was that Microsoft would stay out of this type of functionality, and today’s release is one of an unknown number of apps that we will see come out of Microsoft.

Besides the fact that Microsoft is now on the hook for maintaining this app, they have effectively cut off the potential from the ISV channel. Their work in progress as essentially turned into a big fat tax write-off.

What Next?

Two out of those three partners had already been looking at alternatives to their NAV/BC practice, and I can’t say that I blame them. Licenses are no longer capital investments. Margins are going down with lower subscription fees, so you can no longer afford to focus on smaller businesses as clients. Having to go through a primary CSP means that you have to share what little margin remains. The stack has become much more complex, so you have to hire experts for everything.

One of the last things that are left is to develop your own IP and publish on AppSource. Would you decide to invest in new products if there is a real chance that Microsoft is working on the same thing?

Personally, I think Microsoft is making a huge mistake by creating this type of app. I am not sure if they are capable of taking on the support, and that they will be maintained properly. I am also doubtful about the cooling effect this will have on the partner channel’s willingness to invest in new products.

Most important though is that I am just flabbergasted that they prioritized something like this, when there are SO MANY things still left to improve in the base product.

As I am writing this I am struggling to find a good way to finish this post, I’m clearly not done thinking about this. Let me know in the comments what you think.

Partial Records with SetLoadFields

Fetching and updating records has historically been the greatest culprit of performance problems. The standard way that BC retrieves records is very expensive, since it will always get ALL the fields of a table (and its brethren companion tables). This post covers a (relatively) new option called SetLoadFields, which is used to specify the fields that you want to retrieve.

So What’s the Problem?

The database engine for BC is SQL Server for OnPrem and Azure SQL for SaaS; the business logic translates database operations into T-SQL statements at run time. By default, it issues a SELECT * and that means that for every standard database call, BC retrieves ALL fields from the table. Good for us developers because we never have to think about which fields to fetch. From a performance point of view though this causes a MASSIVE superfluous overhead in data traffic. Some of the most used tables in BC have bazillions of fields, and in any business logic scenario you never need more than a handful of fields.

The problem is exacerbated by the presence of table extensions. Each table extension is represented in the SQL database by a companion table that shares the primary key with the main table. Every time that you retrieve records from the main table, the system also retrieves the fields from the companion tables by issuing a JOIN on the PK fields. You can imagine a popular table like the Sales Line with a dozen table extensions; a SalesLine.FindSet command generates a SQL statement that includes a dozen JOINs.

The problem is that the number of fields that are included in SQL statements has a disproportionate effect on query performance. Read the post that I link to below for more details, but what you need to know is that the same query with all fields can take hundreds of times more than retrieving just half a dozen fields.

Only Get What you Need

To eliminate this overhead, we now have a SetLoadFields command. Basically, what you can do with this command is to define the fields that are included in the SQL statement. Instead of getting all fields and get data that you will never use, you tell BC that you only want your handful of fields.

Need an address from a Vendor? The external document number from an invoice? An Inventory Posting Group from an Item? You don’t have to read 6 million fields to do that anymore.

procedure ShowSomeCode()
    Vendor: Record Vendor;
    Vendor.SetLoadFields(Address,"Address 2",City,"Post Code");
    // do stuff with the address fields and ignore the rest

This code sample generates a SQL statement with a SELECT on just those few fields that are defined in the SetLoadFields command, and it should ignore the companion tables altogether since these are all main table fields.

Read the documentation here and make sure you read how to use it here. For more technical in-depth information on what to do and what happens under the hood (way above my head there), read Mads’ posts here and here.

New Habits

In my day-to-day life as a BC developer I don’t normally see SetLoadFields commands. I even checked the standard objects and it’s actually quite surprising how little it is used there. In a previous life I did a LOT of performance troubleshooting, and this would have been a tremendous help in solving lots of performance problems. I know I will try to make using this command a habit.

Excel Buffer for the Cloud

One of my clients asked me to help them convert an add-on that they developed in C/CIDE into an AppSource app. This add-on includes the functionality to export some data into an Excel file, using the Excel Buffer table.

The Excel Buffer table is also available in AL, but one of the issues is that as soon as you set the target of the extension to ‘Cloud’ (Which as you know is an attribute in app.json), the compiler will scream at you that you can’t use certain functions of the Excel Buffer, because their Scope has been set to on premises. So if your C/AL object uses the ‘OpenExcel’ function, for instance, you can’t use that for AppSource apps because its scope is OnPrem. This type of thing usually takes me days to figure out, so I thought I’d ask Twitter with my favorite community hashtag #bcalhelp

Within a day I received a bunch of helpful suggestions, I just love this community! The one that put me over the top was a phone call with my good friend AJ, who not only showed me, but he also sent me some sample code that he was working on. He’s working on a blog post about this topic himself, so I’ll let him share that and I’ll post a link to his blog once he puts it online. I want to mention Owen too because he had sent me essentially the same suggestions, but to an email address that I hardly ever use anymore, so I didn’t see that until days later.

As you can see by the trigger name, I had to put this into a report object (which I’ll share when I find time to put it in a repo). My main problem was that I needed to be able to provide a way for the user to open the Excel file. For this to work, you use the OpenExcel function. This actually does not open Excel, but what it does instead is it downloads the Excel file into the Downloads folder on your computer, and then you can open that file from there.

Some additional pointers:

  • CreateNewBook creates a new file, with a new sheet. If you already have the file created, and you need to add a sheet to the existing file, then you would use the SelectOrAddSheet function
  • TheWriteSheet function writes the records from the Excel Buffer table into the sheet. Each record represents a cell value
  • You will need to use the NewRow, AddColumn functions to ‘walk the grid’ of the cells in your sheet. Also very useful functions: ClearNewRow and SetCurrent. I ended up adding a GetCurrentRow function to an Excel Buffer table extension
  • The CurrentRow and CurrentCol variables in the Excel Buffer table are your friend. Forget about the letter/numbers of the Excel file itself, just use the row/column numbers
  • SetFriendlyFileName is not mandatory, but otherwise the file will be called ‘Book1’ or something

Like I said before, AJ is working on a post for this as well, and he said he was going to offer a repo with the objects as well. If I don’t forget I’ll create a sample report and offer that as a PR to AJ’s Excel repo.

Translation File Names Must Match App.json

This is a quick follow-up on my previous post about creating a container for modified Base App development, about the translation file issue. After publishing that post, I also reported the error message to the AL repo on Github and to the MicrosoftDocs repo.

As @NKarolak suggested, the names of the translation files must match the name in app.json. I was very skeptical about this, because this was never the case in any of the AppSource apps I’ve worked on, and the Doc for the translation files specifically says that there is no enforced naming of the translation files. It might be a new requirement though.

When I first created my AL workspace by exporting it from my container, the translation files were named as follows:

The name in app.json is ‘Base Application’ so the space character is replaced with ‘%20’ which is the html representation for the space character. Since the original error message did not mention the file name, I did not think that the file name itself was the problem.

I decided to try Natalie’s suggestion and replaced the ‘%20’ with a regular space, and voila, it published the app as expected.

Next, I changed the name in my app.json to ‘Super Base Application’ and it errored out again. Once I changed the translation files to match the name in app.json, it worked again.

Moral of the story: when developing a modified Base App, you have to match the translation files to the name in app.json.

Modified Base App on Docker

How to get started with modifying the Base Application using Docker

Many partners are still focused on doing custom development for their customers with their one-off implementations. MANY of those customers are existing customers with existing NAV systems with existing customized objects. As much as everyone wants to go to extensions only, and most partners see the need and are more than willing to make the necessary changes, the reality is that many of these existing customers do not want to pay for migrating all of their custom modifications. This reality comes with the need to modify the base app. Since C/SIDE is no longer available, the only way to do this is to use VSCode. This post will explain how you can create a Docker container, and use that container to do modifications on the Base Application.

To get started, click here to read the article on I say ‘get started’ because it was not enough to get me all the way there, which is the reason why I wrote this post. This article seems to have been written for an actual installation from the product DVD, and there were some additional things you need to know to make it all work if you want to use Docker. At least, that is per the date of this post, because things may change :). I’ll try to revisit this post if it does change.

Alright, so to make this work, you need a few things:

  • A Docker container that is based on the latest Business Central Docker image.
  • Configure the Service Tier in the container
  • Extract the objects from the container into a new AL workspace
  • Uninstall and Unpublish the Base Application and its dependencies

Create a new Container

For Business Central development I always use the NavContainerHelper module, so before you use any of the commands in this post, update your module:

Update-Module navcontainerhelper

To get the latest Docker image for Business Central I will be using the ‘’ image. You can leave the ‘ltsc2019’ part out if you are not sure about the host OS or if you are on Windows Server 2016. You can substitute ‘na’ for your own localization, or leave that tag out altogether if you want to be on the W1 version. To read about which image to use, visit Freddy’s blog here and follow the links to what you need to know. Here is the script that I used to create my container:

$imageName = ''
$licenseFile = '<path to your BC 15 developer license>.flf'
$ContainerName = 'mysandbox'
$UserName = 'admin'
$Password = ConvertTo-SecureString 'Navision4ever!' -AsPlainText -Force
$Credential = New-Object System.Management.Automation.PSCredential ($UserName, $Password)

New-NavContainer `
    -accept_eula `
    -containerName $ContainerName `
    -imageName $imageName `
    -licenseFile $licenseFile `
    -auth NavUserPassword `
    -alwaysPull `
    -Credential $Credential `
    -includeAL `
    -updateHosts `
    -additionalParameters @("-e customNavSettings=ExtensionAllowedTargetLevel=OnPrem")

I use the ‘-alwaysPull’ switch to make sure that I always have the latest version of the Docker image. The ‘-includeAL’ switch is necessary to include references to the DotNet assemblies in the Docker container. The ‘-additionalParameters’ switch (h/t @tobiasfenster) is used to set the ExtensionAllowedTargetLevel property to ‘OnPrem’. I’ll explain how to set this with a simple PowerShell Cmdlet in a minute.

One more important switch is the ‘-useCleanDatabase’ switch, which can be used to uninstall and unpublish the Base Application and its dependencies, as I will discuss in a little bit. At this point, you have a vanilla Docker container with the latest on premises version of Business Central.

Configure the Service Tier

As the Doc states, there are three things you need to set. It is not very clear exactly how to do that, and not at all how that works on Docker, so let me just explain from scratch.

First, you need to know how to look at, and modify, the Service Tier settings inside the container. Some of these types of commands are available in the navcontainerhelper module, but some of them are not. I did find a Cmdlet to see the settings, but I could not find one to actually modify them. So, to cover all of it, I will show you how you can connect to the container and run regular BC PowerShell Cmdlets from inside the container.

Open a PowerShell ISE window as administrator, and run the commands in the screenshot

Our container name is ‘mysandbox’, and you connect to it by using the ‘Enter-BCContainer’ Cmdlet. You can see how the prompt changes to show you that you are inside the container. At this stage, the navcontainerhelper does not work, so you will have to use the regular BC PowerShell Cmdlets. The next Cmdlet shows you all the properties of the Service Tier that runs inside your container, which in this version of Business Central is called ‘BC’.

According to the Doc, the following settings are important. I am using the names that are used in PowerShell rather than the names in the Doc.

  • ExtensionAllowedTargetLevel should be set to ‘OnPrem’, although it seems that the value ‘Internal’ also works.
  • DeveloperServicesEnabled should be set to true. This should be the default value of this particular setting
  • There is also a mention of the EnableSymbolLoadingAtServerStartup property in the Doc, but I’ve received confirmation (h/t @freddydk) that this property was meant for hybrid C/AL and AL environments, so that is not needed anymore for BC 2019 wave 2

To modify these settings, use the following PowerShell command

Set-NAVServerConfiguration `
      -ServerInstance BC `
      -KeyName ExtensionAllowedTargetLevel `
      -KeyValue OnPrem

After modifying those settings, restart the service tier using the ‘Restart-NAVServerInstance -ServerInstance BC’ command. At that point, the service tier in your container should be configured for doing on premises development. The next thing you need to do is get the application objects out of the container.

Create AL Workspace from Base App

This step is easy, using a navcontainerhelper Cmdlet, so you need to first exit the container (type ‘exit’ and then enter). Then, run this Cmdlet:

$ContainerName = 'mysandbox'
$UserName = 'admin'
$Password = ConvertTo-SecureString 'Navision4ever!' -AsPlainText -Force
$Credential = New-Object System.Management.Automation.PSCredential ($UserName, $Password)

Create-AlProjectFolderFromBcContainer `
    -containerName $ContainerName `
    -alProjectFolder 'C:\MyProjects\BaseApp' `
    -useBaseAppProperties `
    -credential $Credential 

One thing to note here is that the ‘-useBaseAppProperties’ switch uses the properties from the container. You will end up with a fully functioning AL workspace, with an app.json and launch.json that is configured to look inside the container for the objects and the DotNet probing path. You will need to configure this yourself if your configuration needs to be different. But, since we’re making this work for a standard container, we’re going to use the standard configuration as well.

One other important thing to note…. As I am writing this post, I’ve had a persistent error message that prevented me from compiling the app, which I narrowed down to having to remove the translation files. The annoying part is that the error message itself does not mention the translation files, but it started working again after I removed them. In your new BaseApp folder, there is a folder called ‘Translations’. Remove all files from that folder, except the ‘*.g.xlf’ file.

Update 2019/11/27 follow up on the translation file issue:

One final thing to note is that this is just a simple AL workspace. In a real life situation, you are doing this for a particular customer, so you need to think about source control, workspace settings, things like that. There are some capabilities in the Cmdlet, so take a look here to see all the available parameters of the Cmdlet.

The last thing you will need is to download the symbols for the system apps from the container. The Doc also mentions adding the assemblyProbingPaths to the workspace settings, but if you used the ‘-useBaseAppProperties’ switch, that is already taken care of for you and the setting will point to one of the container’s shared folders.

Uninstall / Unpublish Base App

In the previous step, you’ve created an AL workspace with all of the objects from the Base Application. Now, your container already has a Base App, so in order to create a modified Base App, you will have to get rid of the standard one first. You can be a PowerShell warrior and run the Cmdlets in this section, or you can also use the ‘-useCleanDatabase’ switch in the New-BCContainer Cmdlet in the first section. This will remove the Base App and all its dependencies from your container right away.

On to the PowerShell… In the Doc, under bullet 11, you will find the functions to accomplish this. These are regular NAV PowerShell Cmdlets, so you will need to enter the container first:

function UnpublishAppAndDependencies($ServerInstance, $ApplicationName)
     Get-NAVAppInfo -ServerInstance $ServerInstance | Where-Object { 
    # If the dependencies of this extension include the application that we want to unpublish, it means we have to unpublish this application first.
    (Get-NavAppInfo -ServerInstance $ServerInstance -Name $_.Name).Dependencies | Where-Object {$_.Name -eq $ApplicationName}
 } | ForEach-Object {
    UnpublishAppAndDependencies $ServerInstance $_.Name

 Unpublish-NavApp -ServerInstance $ServerInstance -Name $ApplicationName

function UninstallAndUnpublish($ServerInstance, $ApplicationName)
    Uninstall-NavApp -ServerInstance $ServerInstance -Name $ApplicationName -Force
    UnpublishAppAndDependencies $ServerInstance  $ApplicationName


This loads the functions into memory, and then you can run the script:

UninstallAndUnpublish -ServerInstance BC -ApplicationName "Base Application"

This will completely remove the Base App and its dependencies.

Ready to Start Developing

That’s it, you should now be ready to start your development. See how that works. Add a field to a table, add that field to its Card page and hit Ctrl+F5. It will probably take a while to compile, but you should see your new field on the page.

Now I do need to say that I completely and wholeheartedly agree with the entire community, and code customizations should really not be done anymore. All development should be done using extensions instead of change the Base App itself. It makes everyone’s life a lot easier if you minimize the amount of development done to the Base App, so even if you have no other choice, try to design the development in such a way that most of it is in an extension, and only modify the Base App for the parts that you can’t figure out how to do in an extension.

Update 2019/11/27: created a GitHub repo with the scripts

My Take on Using Docker

This past week, there was another post by my good friend Arend-Jan Kauffmann about using Docker directly on Windows 10 (what are you still doing here? Go read AJ’s post!). He had previously written about using Docker in a Hyper-V VM, and he has helped me understand how this all works a number of times. Just to be sure I mention this here, you can read all about the technical details on Tobias Fenster’s blog but that goes over my head very quickly.

The reason why I am writing this is because I am very reluctant to make the step to install Docker directly on my laptop. What works for me at the moment is where I have Hyper-V enabled on my laptop, and I have a VM with just Windows Server 2016 (creating one with Windows Server 2019 is very high on the todo list). My Docker is installed in a snapshot of that VM, and that is where I do all of my development work. I wrote about this before, read it here.

See… I am the king of screwing up my computer. If there is anything, ANYTHING, that will mess up my computer and render it absolutely useless, I WILL find it, and I will kill my computer (I am hearing that in Liam Neeson’s voice by the way). I have had to re-install my laptop so many times because of things that went wrong. When I have a problem like this in my VM, I don’t even spend any time trying to figure out what went wrong (that gives me a headache just thinking about it). All I need to do is delete the snapshot, create a new one, and I’m back up in a matter of minutes. All my dev work is in repos that I sync regularly, so I never have to worry about losing any work.

I’ve read about Docker straight on Windows 10, and it sounds very nice and easy to use. At the same time, I read blog posts and even Tweets that mention damage to the host OS from normal Docker operations, and I just KNOW that if I try it will happen to me. My reluctance to use Docker on Windows 10 directly does not come from wanting to stay in the past, but it is more from the knowledge that I’m going to screw up my computer.

Maybe I’m too cautious, but for now I will stick to my setup and continue to use Docker inside a VM. It works for me, and for now that’s good enough.

Docs on GitHub

Maybe you remember, last year I wrote about signing an App Package file, but that post was really about how I got to collaborate with someone at Microsoft, and one of the things we did was improve the online documentation for this topic.

At the time, I had noticed that there was a feedback button on each page in Docs, and underneath the feedback button it said something like ‘feedback is linked to GitHub Issues’, which led me to wonder if we’d ever see Docs in a repo that we could actually contribute to.

Now today, through a tweet by one of the managers at Microsoft, there was a link to a blog post about that very topic: here it is.

Just think how great this is! Not only do we get access to the source files of the actual documentation, we have a mechanism to contribute to the content. If you ever find yourself confused by any of the documentation, you can either leave your feedback on Docs, or you can make a change and submit a pull request to the repo itself! Either way, the actual system that is used to maintain the docs source files is also used to track issues, and you can create issues yourself in that very system!

This is what we call a BFD 🙂