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

API Publishing for Extensions:

In Business Central, when creating custom APIs like RoomsAPI, it is important to ensure that they are automatically published during the installation or upgrade of the extension.

To achieve this, you can include a codeunit of type Install in the extension that explicitly publishes the custom API (RoomsAPI) as a web service. This ensures that it is available for use immediately after the extension is deployed without requiring manual intervention.

Codeunit Type:

A codeunit of type Install runs when the extension is installed or upgraded. This type of codeunit can be used to perform setup tasks such as publishing web services or APIs like RoomsAPI.

Why Not Other Options?

Option A (default API configuration): This would not automatically publish the RoomsAPI. Default APIs do not cover custom APIs.

Option B (enable APIs for the environment): Enabling APIs in Business Central allows the standard APIs to be used, but custom APIs still need to be manually published.

Option C (publish via Web Services page): This would work but requires manual intervention to publish RoomsAPI, which does not fulfill the requirement of automatic publishing during installation.

Reference Documentation:

Publishing APIs in Extensions

Codeunit Types in Business Central

https://api.businesscentral.dynamics.com/v2.6/myTenant/myEnvironment/api/alpine/integration/rooms

For the requirements provided, the appropriate page types should be selected as follows:

Display relevant insights in the Housekeeping Role Center: HeadlinePart

Display the additional information for the Room table: FactBox

Configure the first installation: StandardDialog

Comprehensive Detailed ExplanationIn the context of Microsoft Dynamics 365 Business Central, page types are crucial for determining how information is presented to the user.

HeadlinePart: This page type is designed to display key data and insights in a concise and visually appealing manner, often used in Role Centers to highlight important information. It is suitable for the Housekeeping Role Center to display relevant insights.

FactBox: This page type is used to display supplementary information related to a selected record in the main part of the page. It's often used to show additional details about a record in a list, card, or document page. In this scenario, it is suitable for showing additional information about a specific Room when viewing the Room table.

StandardDialog: This is a page type that provides a modal dialog for user interaction, commonly used for setup wizards, confirmations, and input forms that require user action before proceeding. This is appropriate for configuring the first installation, where a step-by-step guided interaction is necessary.

For the Install codeunit required for the extension used for installing or updating the Housekeeping app, you should use the following data type and declaration:

Data type for information: ModuleInfo

Start of the declaration of the method or procedure to perform the tasks: local procedure

In AL language, which is used for developing extensions in Business Central, an Install codeunit is a special type of codeunit that is used to handle installation or upgrade logic for an extension.

ModuleInfo is a data type that contains information about the current extension, such as its version. It is typically used within the OnInstallAppPerCompany or OnUpgradePerCompany triggers of an Install codeunit to determine if the app is being installed for the first time or upgraded.

A local procedure within an Install codeunit is a method that is only accessible within the codeunit itself. It is not visible to other objects or extensions. This is suitable for tasks that are internal to the installation process and should not be exposed globally.

These selections align with the requirements of handling installation and update procedures in a controlled and encapsulated manner within Business Central extensions.

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).

Here is the most logical sequence of actions for implementing the Issue Management module in Business Central and exposing the PostIssue method:

Correct Order:

Create a codeunit named "Issue Management Impl." and set the value of Access property to Internal.

This is the first step because Issue Management Impl. is the implementation layer where the actual business logic resides, and setting it to Internal ensures that it is only accessible from within the module, following best practices in encapsulation.

Create a local procedure named PostIssueImpl in the "Issue Management Impl." codeunit.

This step adds the actual PostIssueImpl method, which contains the core logic of posting an issue.

Create a codeunit named "Issue Management" and set the value of Access property to Public.

After defining the implementation logic, you need to create a public-facing Issue Management codeunit to expose the service externally.

Create a PostIssue procedure in the "Issue Management" codeunit, and in it call the PostIssueImpl method.

Lastly, expose the PostIssue method in the Issue Management codeunit, which will internally call the PostIssueImpl method, completing the chain.

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】.

The task is to identify unwanted incoming web service calls during the last seven days. To do this, we need to look at KQL (Kusto Query Language) queries that would filter out web service calls based on the timestamp (to ensure the calls are within the last seven days) and by certain characteristics that would indicate they are unwanted, such as the wrong type of protocol (SOAP in this case, as Contoso Ltd. plans to dismiss using it).

Looking at the options:

Option A: This query selects all traces where the timestamp is within the last 7 days and where the custom dimension has a value of 'RT0008', and where the category is either 'ODataV4', 'ODataV3', or 'Api'. This query would show all API calls except SOAP, so it does not directly answer the question about unwanted calls.

Option B: This query filters for traces with a timestamp within the last 7 days, where 'RT0008' is present, and specifically looks for the category 'SOAP'. This query is correct because it directly targets SOAP calls, which are the unwanted calls according to Contoso Ltd.'s plans.

Option C: Similar to option B, this query filters for traces within the last 7 days and looks for 'RT0008' but uses the equality operator for the category 'SOAP'. This would also correctly return the unwanted SOAP calls.

Option D: This query also filters for traces within the last 7 days, but it excludes the 'ODataV4' category, which doesn't necessarily target the unwanted SOAP calls.

Option E: This query selects traces where the timestamp is within the last 7 days and the custom dimension has 'RT0008'. However, it filters out categories 'ODataV4' and 'Api', which does not directly help in identifying the unwanted SOAP calls.

Therefore, the queries that should be used to determine if there are unwanted incoming web service calls (SOAP calls) in the tenant during the last seven days are Options B and C. These queries are specific to identifying SOAP protocol usage, which is what Contoso Ltd. considers unwanted.

In the context provided by the case study, when calling an API action from a mobile application, the correct format for a POST request to an action in Business Central typically involves specifying the entity (/issues), the ID of the entity (88122e0e-5796-ec11-bb87-000d3a392eb5), and the action to be called (/Copy). The action name should match the exact name as defined in the AL code, which is case-sensitive.

Option A is incorrect because it uses a non-standard format for the action call.

Option B uses the PATCH method, which is generally used for update operations, not for calling actions.

Option C is correct as it uses the POST method, which is appropriate for calling actions, and correctly specifies the entity, ID, and action name.

Option D is incorrect because the action name /copy is in lowercase, while AL is case-sensitive, and it should match the case exactly as defined in the code.

Option E incorrectly adds 'MicrosoftNAV' before the action name, which is not standard for calling actions in Business Central APIs.

Hence, the correct action to use when calling the Issue API action from the mobile application is given in Option C.

 Verbosity::Critical: This ensures that the telemetry logs the failure as a critical event.

 DataClassification::CustomerContent: This helps classify the error as related to customer data.

 TelemetryScope::All: This ensures that the error is visible across all relevant telemetry scopes, making it easier to monitor the issue in real-time.

The correct sequence of actions to configure telemetry for the SaaS tenant and test whether the ingested signals are displayed would be:

Create an Azure Application Insights instance by using the Azure Portal in the Customer's subscription.

Select the environment in the Admin Center and place the connection string in the Application Insights Connection String field.

Select the Application Insights instance, select Logs and then inspect the Traces table.

To set up telemetry for a SaaS tenant using Azure Application Insights, you need to follow these steps:

Create an Azure Application Insights instance: This is the first step where you create an instance in Azure that will collect the telemetry data. This should be done in the customer's Azure subscription because it's their data that you're monitoring.

Configure the SaaS tenant to use the created Application Insights instance: This involves entering the correct connection string in the Business Central Admin Center so that telemetry data from the tenant is sent to the Application Insights instance.

Verify that telemetry is being collected: After configuring, you would check if the telemetry is arriving as expected by inspecting the Traces table in the Azure Application Insights instance. The 'Traces' table holds the telemetry data, which you can query to verify that the correct signals are being ingested.

 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, fields in tables are assigned specific data types that determine the kind of data they can store. For the Non-conformity table mentioned in the case study, the following data types should be used:

Date for the Non-Conformity Date field: This is because the Non-conformity Date field is required to store only the date when the non-conformity was recorded. The Date data type is appropriate for storing dates without times.

Code for the Non-Conformity Number field: The Non-conformity Number field is described to use alphanumeric values with a format that includes "NC" and the year, like "NC24-001". In Business Central, the Code data type is used for fields that store alphanumeric keys. It is a text field with a limited length, which makes it suitable for number series that contain letters and numbers.

Other options are not suitable:

A. Integer for the Non-conformity Number field: This would not be appropriate because the Non-conformity Number includes alphanumeric characters and not just integers.

B. DateTime for the Non-Conformity Date field: This is not correct because there is no requirement to store the time alongside the date.

C. Char for the Non-Conformity Number field: Char data type is not typically used in Business Central for number series or identifiers. The Code data type is preferred for this purpose.

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

Instructions to use for Incident Date and Status fields:

The correct instruction is "Incident Date" := Workdate(); "Status" := Status::Open;. This ensures that when a new record is created, the Incident Date is set to the current work date, and the Status field is initialized to 'Open'. This is essential for ensuring that the incident data is always timestamped and correctly marked upon creation.

Trigger to introduce the function:

The correct trigger is Trigger OnModify. This trigger ensures that when a record is modified, such as when an update to the status is made (e.g., from Open to Closed), the necessary logic will be executed to handle the update of fields like Incident Date and Status.

Step-by-Step References:

Workdate Function in AL

Triggers in AL

You are customizing Business Central using Visual Studio Code and JSON files for configuration.

You plan to:

Open page 21 after publishing.

Enable debugging.

Disable the capability to download the source code.

Which configurations should you add?

The options involve two primary JSON files: launch.json and app.json, and configuration tags like startupObjectId and resourceExposurePolicy.

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.

To create a query that assigns vendors to items in Business Central, use the following code blocks in sequence:

dataitem(Vendor; Vendor)

dataitem(Item; Item)

DataItemLink = "Vendor No." = Item.Vendor_No;

Creating a query:In Business Central, a query object is used to combine data from multiple tables. You start by specifying each table as a data item. In this case, you would start with the Vendor table and then the Item table. After specifying the data items, you need to link them together. The DataItemLink property is used to establish a relationship between two data items based on a common field. Here, you are linking the Vendor and Item tables on the "Vendor No." field, which is present in both tables. This link ensures that the query will return a dataset that includes related records from both tables based on the vendor number. The order of the code blocks ensures the logical flow and relationships between tables as required for the query.

When exporting data from Business Central and the requirement is for the data to be in a non-fixed length and width CSV format, the Format property of the XMLport should be set to VariableText (B). The VariableText format is designed for handling data exports where the fields are separated by a delimiter, such as a comma or tab, which is typical of CSV (Comma-Separated Values) files. This format allows for the flexibility needed when dealing with varying field lengths, as it does not enforce a fixed width for each field, making it ideal for CSV data exports. Setting the Format property to FixedText (C) would enforce a fixed width for each field, which is not suitable for CSV files, while the XML format (A) is used for exporting data in an XML structure, which is different from the CSV format requirements.

 Add Clear(PurchaseLine); as a line before line 01 of the code: No

 Add PurchaseLine.SetFilter("Line No."; '>0') as a line after line 06: Yes

 Change the filter on line 06 from a "No." field to a "Document No." field: No

 Remove "not" in line 07: No

 Add Clear(PurchaseLine); as a line before line 01 of the code.

No

You do not need to clear the PurchaseLine record before running the query, because the SetRange filters will take care of setting the correct context.

 Add PurchaseLine.SetFilter("Line No."; '>0') as a line after line 06.

Yes

Adding a SetFilter on the "Line No." field ensures that you're checking for actual purchase lines greater than 0, which are valid lines. This would fix the issue where the check might return false even when lines exist.

 Change the filter on line 06 from a "No." field to a "Document No." field.

No

The filter on the No. field is correct, as it's filtering based on the purchase order number. Changing this to Document No. is unnecessary.

 Remove "not" in line 07.

No

The not in line 07 is necessary because IsEmpty() returns true when no lines are found. To correctly return a boolean indicating whether the purchase order has lines, you need to negate the result of IsEmpty().

To create an HTTP GET request that connects to an external REST service in a Business Central online environment, the solution to use is the HttpClient data type variable (E). The HttpClient data type in AL language is designed for sending HTTP requests and receiving HTTP responses from a resource identified by a URI. This makes it the ideal choice for interfacing with external REST services, as it provides the necessary methods and properties to configure and execute HTTP GET requests, handle the responses, and process the data returned by the REST service. This approach is more direct and flexible compared to using specific codeunits like "Web Request Helper" (B) or "Http Web Request Mgt" (D), which might not provide the same level of control or specificity needed for RESTful interactions.

A user observes error messages such as:

"Unhandled UI: Message"

"Unhandled UI: Confirm"

These messages indicate that the test code is not handling system prompts like Message and Confirm dialogs, which can appear during test execution.

Options Explanation:

Message Handler and Confirm Handler methods are used to intercept and handle these UI prompts during automated testing.

These methods should be added to the test runner codeunit, which is responsible for running the tests and handling these system-level interactions.

Language table → System layer

Activities Cue table → Base layer

Extension Management codeunit → System layer

Business Unit Card page → Base layer

Application Layers in Business Central:

In Business Central, there are different layers such as Base and System, which represent different levels of the application architecture. Here's a breakdown of where each object is likely to belong based on typical Business Central architecture:

Language Table:This table typically belongs to the System layer, as language and localization features are often part of the foundational aspects of the system.

Activities Cue Table:This would likely be found in the Base layer because it involves business logic that supports user interface elements (like activity cues) specific to the Business Central application.

Extension Management Codeunit:The Extension Management Codeunit likely belongs to the System layer, as it deals with handling extensions, which is closely related to the core system functionality for managing and deploying changes.

Business Unit Card Page:This object would typically be part of the Base layer, as it is a business-specific object that handles the user interface for business unit data, part of the core Business Central application.