Creating your first connector: Hello World

Hello World sample

This sample provides a simple data source extension that can be run in Visual Studio, and loaded in Power BI Desktop. As an overview, this sample shows the following:

• 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 project called "HelloWorld" and copy in the following M code, and then follow the rest of the instructions to be able to open it in PowerBI.

In the following connector definition you'll 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 PowerBI. You can search for "hello" to find your connector in the Get Data dialog.

This step will bring 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 will tell you that it's a "Preview connector", since Beta is set to true in the query. Since there's no authentication, the authentication screen will present a tab for Anonymous authentication with no fields. Press Connect again to finish.

Finally, the query editor will come 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.