Creating your first connector: Hello World

This sample provides a simple data source extension that can be run in Visual Studio Code, and loaded in Power BI Desktop.

Hello World sample

As an overview, this sample shows:

• Exporting function (HelloWorld.Contents), which takes an option text parameter.
• Defining a data source kind that:
  • Declares that it uses Implicit (anonymous) authentication.
  • Uses string resources that allow for localization.
  • Declaring UI metadata so the extension can show up in the Power BI Desktop Get Data dialog.

Following the instructions in Installing the PowerQuery SDK, create a new connector called "HelloWorld", copy in the following M code and paste it in the HelloWorld.pq file of your connector workspace, and then follow the rest of the instructions to be able to open it in Power BI.

In the following connector definition you find:

• A section statement.
• A data source function with metadata establishing it as a data source definition with the Kind HelloWorld and Publish HelloWorld.Publish.
• An Authentication record declaring that implicit (anonymous) is the only authentication type for this source.
• A publish record declaring that this connection is in Beta, what text to load from the resx file, the source image, and the source type image.
• A record associating icon sizes with specific PNGs in the build folder.

section HelloWorld;
 
[DataSource.Kind="HelloWorld", Publish="HelloWorld.Publish"]
shared HelloWorld.Contents = (optional message as text) =>
    let
        message = if (message <> null) then message else "Hello world"
    in
        message;
 
HelloWorld = [
    Authentication = [
        Implicit = []
    ],
    Label = Extension.LoadString("DataSourceLabel")
];
 
HelloWorld.Publish = [
    Beta = true,
    ButtonText = { Extension.LoadString("FormulaTitle"), Extension.LoadString("FormulaHelp") },
    SourceImage = HelloWorld.Icons,
    SourceTypeImage = HelloWorld.Icons
];
 
HelloWorld.Icons = [
    Icon16 = { Extension.Contents("HelloWorld16.png"), Extension.Contents("HelloWorld20.png"), Extension.Contents("HelloWorld24.png"), Extension.Contents("HelloWorld32.png") },
    Icon32 = { Extension.Contents("HelloWorld32.png"), Extension.Contents("HelloWorld40.png"), Extension.Contents("HelloWorld48.png"), Extension.Contents("HelloWorld64.png") }
];

Once you've built the file and copied it to the correct directory, following the instructions in Installing the PowerQuery SDK tutorial, open Power BI. You can search for "hello" to find your connector in the Get Data dialog.

This step brings up an authentication dialog. Since there's no authentication options and the function takes no parameters, there's no further steps in these dialogs.

Press Connect and the dialog tells you that it's a "Preview connector", since Beta is set to true in the query. Since there's no authentication, the authentication screen presents a tab for Anonymous authentication with no fields. Press Connect again to finish.

Finally, the query editor comes up showing what you expect—a function that returns the text "Hello world".

For the fully implemented sample, see the Hello World Sample in the Data Connectors sample repo.