Creating a Custom Connection in Power BI

Creating custom connections in Power BI enables you to access data sources not covered by built-in connectors. This involves using Power Query M Language to define data sources and transformation processes.

Introduction

Creating a custom connection in Power BI allows you to connect to data sources that are not available through the built-in connectors. To create a custom connection, you'll need to use Power Query M Language to define the data source and transformation logic. Here's a high-level overview of the steps.

Install Power Query SDK (M Extensions)

Before you can create custom connectors, you need to install the Power Query SDK (also known as M Extensions) for Visual Studio. You can download it from the Visual Studio Marketplace.

Open Visual Studio

Launch Visual Studio after the Power Query SDK is installed.

Create a New Project

In Visual Studio, create a new project of type "Power Query (M) Custom Connector."

Define the Data Source

In the project, you'll define the data source and any required connection parameters. You'll need to write M code for this purpose.

let
    source = [
        Authentication = [
            OAuthClientId = "",
            OAuthClientSecret = "",
            OAuthTokenUrl = ""
        ],
        Label = "Custom Data Source",
        Type = "Web.Contents"
    ]
in
source

Replace the placeholders in the code with your authentication details and connection information.

Define Query Logic

You can specify query logic using M code. This includes transforming and shaping the data as needed for your custom data source.

let
    source = Web.Contents("https://example.com/api/data"),
    json = Json.Document(source),
    table = json[DataTable]
in
table

Customize the code to fetch and transform data according to your requirements.

Test the Connector

You can test the custom connector within Visual Studio by using the "Test Query" option. This allows you to verify that your connector is working as expected.

Build the Connector

Once you're satisfied with your custom connector, build the project to generate the necessary files.

Install the Connector

After building the project, you'll get a .mez file. You need to copy this .mez file to the Custom Connectors folder on your computer. The folder location may vary depending on your Power BI installation.

Restart Power BI

Close and reopen Power BI Desktop to make the custom connector available.

Use the Custom Connector

In Power BI Desktop, go to "Home" > "Get Data" and choose your custom connector from the list of data sources. You can then use it to connect to your custom data source and load the data into Power BI.

Configure Privacy Levels (Optional): Depending on your data source and security requirements, you may need to configure privacy levels to control how data from different sources is combined and shared within your Power BI report.

Creating custom connectors in Power BI can be complex, especially for more advanced scenarios. It's recommended to refer to Microsoft's official documentation and seek assistance from forums or communities if you encounter any issues or need further guidance.