MB-820 Microsoft Dynamics 365 Business Central Developer Questions and Answers

In the context of Microsoft Dynamics 365 Business Central, an extension may not appear in the tenant for several reasons, particularly after an upgrade to a new major version.

Option A suggests that the extension was published as a DEV extension, which typically would not cause it to disappear after an upgrade because DEV extensions are intended for development and testing within sandbox environments.

Option B indicates that the extension was not compatible with the new version within 60 days of the first notification. This is a likely reason because Microsoft enforces compatibility rules, and extensions that are not made compatible within the specified timeframe might be removed or disabled.

Option C refers to the extension being published as a PTE (Per-Tenant Extension) and mentions the Platform parameter not being updated. This could cause issues, but not specifically the disappearance of the extension after an upgrade.

Option D expands on Option C by adding that both the Platform and Runtime parameters were not updated in the application file. This is a critical aspect because if these parameters are not correctly set to indicate compatibility with the new version of Business Central, the extension could be disabled or removed.

Option E is similar to Option B but mentions a 90-day period. This option does not align with standard Business Central practices for version compatibility requirements.

Therefore, the two possible reasons for the disappearance of the extension in the tenant after an upgrade are that the extension was not compatible with the new version within the required timeframe (Option B) and that the extension was published as a PTE without the Platform and Runtime parameters being updated (Option D).

Code Segment Analysis:

The AL code is trying to read JSON data from a response and process it to extract subcontracting order numbers. It uses JsonToken, JsonObject, and JsonArray to work with the JSON data.

JToken.ReadFrom(Data): This line reads the incoming JSON data and converts it into a token. It processes the full JSON body so you can start working with it.

JToken.SelectToken("results"): This line selects the part of the JSON containing the results array. The key "results" is where the JSON response data is expected to be found.

JsonArray: Once the results are extracted, they are stored as an array, and each element in the array (which is expected to contain subcontracting order numbers) is processed.

SubcontractingOrderNo: The extracted order_no from the JSON is stored in this variable.

Breakdown of Steps:

JToken.ReadFrom(Data): This step reads the entire JSON response.

JToken.SelectToken("results"): This step selects the results array from the JSON response.

JArray.AsArray(): This step converts the selected results token into a JSON array that can be iterated over.

GetValueAsText(JToken, 'order_no'): This step retrieves the order_no from each element in the array.

Correct Code Completion:

JToken.ReadFrom(Data): This is the correct method to read the incoming JSON response, as it will convert the string into a JsonToken that can be further processed.

JToken.SelectToken("results"): This is the correct method to extract the results array from the token. This method looks for the key "results" in the JSON and retrieves the relevant array.

Final Code Segment:

al

Copy code

procedure ReadJsonData(Data: text)

var

JToken: JsonToken;

JObject: JsonObject;

JArray: JsonArray;

SubcontractingOrderNo: Code[20];

begin

if Data = '' then

exit;

JToken := JToken.ReadFrom(Data); // Step 1: Read the JSON response data.

JToken := JToken.SelectToken('results'); // Step 2: Select the "results" array.

JArray := JToken.AsArray(); // Convert the token into a JSON array.

foreach JToken in JArray do begin

SubcontractingOrderNo := GetValueAsText(JToken, 'order_no'); // Retrieve the order number.

end;

end;

JToken.ReadFrom(Data): This reads the raw JSON data string and converts it into a JSON token that can be processed.

JToken.SelectToken("results"): This extracts the results array from the JSON data.

JArray.AsArray(): Converts the token into an array so we can iterate over it.

GetValueAsText(JToken, 'order_no'): Extracts the order_no value from each item in the array.

 Upgrade codeunit trigger: OnValidateUpgradePerDatabase

Since the question specifies that you are handling data upgrades, and you need to use validation before upgrading at the database level, the correct choice is OnValidateUpgradePerDatabase. This method ensures that the upgrade process is validated before applying to the entire database, making it more efficient when data affects multiple companies or structures.

 DataTransfer method to use: CopyRows

CopyRows is the appropriate method when you are handling large data transfers between tables, especially in an upgrade scenario where you are migrating or transferring data from one table to another. It copies entire rows of data and is optimal for bulk data operations during upgrades.

In Microsoft Dynamics 365 Business Central, when configuring snapshot debugging, it is crucial that the parameters in the configuration file are correctly set. From the options provided, the issue with the debugger not starting correctly is most likely due to an incorrect "userId" parameter.

Option A is the cause of the problem. The "userId" parameter must be the GUID of the user, not the username. The snapshot debugger needs the exact GUID to attach to the right session for debugging.

Option B is incorrect because "breakOnNext" set to "WebClient" is a valid setting. This tells the debugger to break on the next client action in the web client, which is a typical scenario.

Option C is not the cause of the problem. The "userId" parameter is meant to specify which user session to debug, and this works in conjunction with the "breakOnNext" parameter.

Option D is incorrect as the "executionContext" parameter does not need to be set to "Debug" for snapshot debugging to work. "DebugAndProfile" is a valid value for the "executionContext" parameter, as it allows for debugging and collecting performance information.

Therefore, the reason why the debugger does not start correctly is due to Option A: The "userId" parameter must have the GUID of the user specified, not the username.

In Business Central development using AL (the language for Business Central extensions), the use of access modifiers defines how variables and procedures are accessed within and outside of an object or codeunit.

Access Modifiers in AL:

Public: A public variable can be accessed from any object or codeunit within the same module or extension.

Protected: This restricts access to the current object and objects that inherit from the current object. However, in AL (at least in versions used for Business Central), the Protected access modifier is used with methods but not variables.

Internal: This modifier restricts the visibility to the current extension. This means that variables or methods declared as internal can only be accessed from within the same extension. This is appropriate when you want to provide functionality that is shared within the extension but not exposed externally.

Local: This restricts the variable or method to the current object or method where it is declared. It cannot be accessed from anywhere else, even within the same extension.

Scenario Justification:

In the scenario for Contoso, Ltd., IssueTotal is a global variable in the ISSUE BASE extension, and the ISSUE EXT extension needs to access it. Therefore, the variable cannot be declared as Local, because this would restrict access to just the current object (or method).

Using Public would expose the variable outside of the extension, which is unnecessary because you only want other parts of the extension (specifically the ISSUE EXT extension) to have access.

The best choice in this case is Internal because it restricts access to the variable to within the same extension, which includes the base extension and any dependent extensions like ISSUE EXT. It strikes the right balance between visibility and encapsulation.

Microsoft Dynamics 365 Business Central Developer References:

Access Modifiers in AL: Microsoft's documentation on AL provides the details on access modifiers, where it is specified that internal variables can be accessed within the extension, and the public variable is accessible across all extensions【source: Microsoft Learn on AL Programming】.

Best Practices for AL Development: Business Central development best practices suggest keeping variables internal unless they need to be accessed outside of the current extension【source: Microsoft Learn on AL development guidelines】.

https://learn.microsoft.com/en-us/dynamics365/business-central/dev-itpro/developer/properties/devenv-dataaccessintent-property

 Subtype: Install

 Trigger: OnInstallAppPerCompany

You are developing a codeunit that should only run during the installation of an extension package.

Options:

Subtype: The correct subtype is Install, as it indicates that the codeunit runs only when the extension is being installed.

Trigger: The correct trigger for running during installation is OnInstallAppPerCompany, which handles code execution when the app is installed for a specific company.

To prevent a caption from being translated in an extension for Microsoft Dynamics 365 Business Central, you should add the Locked = true parameter to the Caption (C). This parameter explicitly marks the caption as locked for translation, ensuring that it remains unchanged across different language versions of the extension. This approach is useful for specific terms, brand names, or other elements within the application that should remain consistent regardless of the user's language settings. Unlike the other options, which involve manual manipulation of the translation file or properties, setting Locked = true directly in the AL code provides a clear, maintainable, and error-proof method to exclude specific captions from the translation process.

When creating a test codeunit in Microsoft Dynamics 365 Business Central to write unit test functions, the SubType property (A) of the codeunit should be set to Test. This property is crucial for defining the codeunit's purpose and behavior within the application. By setting the SubType property to Test, you are indicating that the codeunit contains test functions intended to validate the functionality of other parts of the application, such as customizations or new developments. This distinction ensures that the testing framework within Business Central recognizes the codeunit as a container for test functions, allowing it to execute these functions in a testing context, which can include setting up test data, running the tests, and cleaning up after the tests have completed.

In Business Central, when creating an entitlement object to enable transactability for AppSource apps and mapping it to a plan in Partner Center, the Type property of the entitlement object should be set to PerUserServicePlan (A). The PerUserServicePlan type is used to define an entitlement that is based on a service plan, which is typically how transactability features are managed for apps distributed through AppSource. This type of entitlement allows for the mapping of specific features or capabilities of the app to a service plan in Partner Center, enabling granular control over what users are entitled to use based on their subscription. The other values, such as Implicit (B), Unlicensed (C), and Role (D), are used in different contexts and do not apply to the scenario of mapping an entitlement object to a plan for AppSource apps.

Create an enum object named Approver and include all options.

Reasoning: First, you must define the set of options (Hotel manager, Restaurant manager, etc.). In modern AL development, Enums are the standard way to create option sets because they are extensible.

Create a table extension object for an Item table with an Approver field of enum type named Approver in the field section.

Reasoning: Next, you need to add the actual data field to the database. Since the "Item" table is a standard base table, you use a table extension. Tables use a fields section to define data columns. You reference the Enum created in step 1 here.

Create a page extension object that extends the Item Card object. Add the field to the layout section.

Reasoning: Finally, to allow users to see and edit this new field on the screen, you must extend the "Item Card" page. Pages use a layout section to determine where controls appear.

This event occurs before posting a sales document.

PreviewMode is available in the parameters, which allows checking whether the process is being run in preview mode.

This event is typically used for sales order posting and can be used for both shipping and invoicing.

This event matches the requirements because:

You can check if PreviewMode is false.

It can run for both shipping and invoicing.

In line 13, replace the Add method with Insert. = NO

In line 15, replace the WriteTo method with ReadFrom. = NO

Change the ItemObject variable type from JsonObject to JsonToken. = NO

Move line 08 in the beginning of REPEAT .. UNTIL. = YES

The provided code is intended to serialize a list of items from the Item table into a JSON array format. Here is a breakdown of the code and the necessary corrections:

In line 13, "ItemsArray.Add(ItemObject)": This line is correctly using the Add method to add the ItemObject to the ItemsArray. The Add method is the correct method to use for adding items to a JsonArray. Therefore, there is no need to replace Add with Insert.

In line 15, "ItemsArray.WriteTo(RequestText)": The WriteTo method is used correctly to serialize the ItemsArray into a JSON formatted string and store it in the RequestText variable. The ReadFrom method is used for the opposite operation, i.e., to deserialize a JSON formatted string into a JsonArray, which is not the goal in this context. Hence, no change is needed here.

Change the ItemObject variable type from JsonObject to JsonToken: The ItemObject variable is intended to hold JSON objects representing individual items, making JsonObject the appropriate type. JsonToken is not a type used in this context within AL for Business Central, and thus the variable type should remain as JsonObject.

Move line 08, "Clear(ItemObject)": This line should be moved inside the repeat loop to ensure that the ItemObject is cleared for each item in the loop. Placing it before the repeat would only clear it once before the loop starts, which could lead to incorrect serialization as the previous item's properties would not be cleared from the ItemObject.

The logic for serializing records into JSON is a common operation when interfacing with APIs or web services in Business Central, and the pattern shown in the code is typical for such operations.

codeunit 52102 "POS API Management"

{

Access = Public;

Permissions = TableData "POS Information" = rwdx;

trigger OnRun()

begin

readAPI();

end;

procedure readAPI()

begin

// Your code here to read from the POS API

end;

}

var

TempBlob: Codeunit "Temp Blob";

IncidentOutStream: OutStream;

IncidentInStream: InStream;

ImageFilter, FileName: Text;

begin

// Initialize the TempBlob and streams

TempBlob.CreateOutStream(IncidentOutStream);

Rec.Image.ExportStream(IncidentOutStream); // 'Rec' refers to the current Room Incident record

TempBlob.CreateInStream(IncidentInStream);

// Set the filters and filename for the image

ImageFilter := 'Image Files (*.bmp,*.jpg,*.jpeg,*.gif)|*.bmp;*.jpg;*.jpeg;*.gif';

FileName := 'Customer Picture';

// Prompt the user to download the image

if not DownloadFromStream(IncidentInStream, '', 'Download Incident Picture', '', ImageFilter, FileName) then

Error('Unable to download the image.');

end;

field(3; "Receipt No."; Code[20])

{

DataClassification = CustomerContent;

TableRelation = "Purch. Rcpt. Header"."No." where ("Buy-from Vendor No." = field("Vendor No."));

}

Field Declaration:

The field(3; "Receipt No."; Code[20]) part defines the field in the table with ID 3 and type Code with a length of 20. This field will hold the receipt number.

DataClassification:

CustomerContent is selected for the DataClassification property, which categorizes the data for privacy and compliance management. This aligns with Business Central's recommendations for handling sensitive data in customer-related tables.

TableRelation Property:

The TableRelation property links the "Receipt No." field to another table, which in this case is the "Purch. Rcpt. Header" table. This ensures that only valid receipt numbers from the Purchase Receipt Header table can be selected or entered in this field.

Relation Filter:

The filter condition is applied using the where clause. It ensures that the Receipt No. is only from the Purchase Receipt Header records where the "Buy-from Vendor No." matches the "Vendor No." of the current record.

The condition field("Vendor No.") is selected from the drop-down as shown in the image. This links the vendor information in the non-conformity table to the receipt in the Purchase Receipt Header table.

By linking the "Vendor No." fields, you ensure that only receipt numbers from the correct vendor are available, which improves data consistency and reduces errors during data entry.

References to AL Language:

The TableRelation property is frequently used to create references between tables in Business Central. In this case, the correct relationship between the "Purch. Rcpt. Header" and the Non-conformity table is established using the TableRelation and filter.

Reference Documentation:

AL TableRelation Property

AL Field Syntax

StrMenuHandler is used to simulate the selection of an option from a string-based menu, such as the "Ship," "Invoice," or "Ship & Invoice" options when posting a sales order. This handler allows you to programmatically select an option during automated testing.

Other handlers, such as SessionSettingsHandler or SendNotificationHandler, do not simulate the selection of menu choices, which is specifically required in this scenario.

For more details on StrMenuHandler and how it simulates user interaction with menu choices, refer to the Test Handlers in Business Central.

HeadLinePart

FactBox

NavigatePage

 Design pattern for the setup table:

The correct selection here is Adapter. The Adapter design pattern is commonly used when you need to handle integration points or create a setup table that acts as an intermediary for data manipulation, which fits the requirement for the configuration of the non-conformity functionality.

 Data type of the primary key field:

The correct data type is Code. In Business Central, when creating a table with a primary key field, the Code data type is typically used for fields such as document numbers, codes, and identifiers. For a setup table, a Code field is appropriate for keys like "No." series or setup identifiers.

 Property required to prevent users from adding records:

The correct property is InitValue. This property is used to set initial values for fields and can be configured in such a way that users are prevented from adding records directly, typically enforcing control over record creation and editing in configuration scenarios.

Read Scale-Out:

Read scale-out is a feature in Business Central that allows you to improve performance by distributing read-only queries (such as the ones from the ticketAPI) across multiple read replicas in the cloud database. This reduces the load on the primary database and helps improve the response time for read-intensive operations, like analyzing POS data through the ticketAPI.

Data Access Intent - ReadOnly:

When enabling read scale-out, you can configure the DataAccessIntent property of APIs to be ReadOnly. This directs the system to use read replicas to handle read-only queries, which enhances performance by offloading such queries from the primary database.

Why Not Other Options?

Option A (ODataReadonlyGetEnabled): This parameter is unrelated to read scale-out and primarily affects OData services behavior, not API performance tuning.

Option B (AccessByPermission): Setting the permission to Read does not directly affect the performance. It only controls access based on user permissions.

Option D (DataAccessIntent ReadOnly): While setting this property to ReadOnly helps in read-only operations, enabling read scale-out (option C) ensures the underlying infrastructure is optimized to handle such read operations, which is the fundamental action required.

Reference Documentation:

Read Scale-Out in Business Central

Data Access Intent in AL