Handling Data Access

Data Source Functions

A Data Connector wraps and customizes the behavior of a data source function in the M Library. For example, an extension for a REST API would make use of the Web.Contents function to make HTTP requests. Currently, a limited set of data source functions have been enabled to support extensibility.

• Web.Contents
• OData.Feed
• Odbc.DataSource
• AdoDotNet.DataSource
• OleDb.DataSource

Example:

[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;

Data Source Kind

Functions marked as shared in your extension can be associated with a specific data source by including a DataSource.Kind literal attribute on the function with the name of a Data Source definition record. The Data Source record defines the authentication types supported by your data source, and basic branding information (like the display name / label). The name of the record becomes its unique identifier.

Each function associated with the same data source must have the same required function parameters, including name, type, and order. (For purposes of Data Source Kind, a parameter is not considered required if it is marked optional or if its metadata contains DataSource.Path = false.)

Functions for a specific Data Source Kind can only use credentials associated with that Kind. Credentials are identified at runtime by performing a lookup based on the combination of the function's required parameters. For more information about how credentials are identified, see Data Source Paths.

Example:

HelloWorld = [
    Authentication = [
        Implicit = []
    ],
    Label = Extension.LoadString("DataSourceLabel")
];

Properties

The following table lists the fields for your Data Source definition record.

Field	Type	Details
Authentication	record	Specifies one or more types of authentication supported by your data source. At least one kind is required. Each kind will be displayed as an option in the Power Query credential prompt. For more information, see Authentication Kinds.
Label	text	(optional) Friendly display name for this extension in credential dialogs.
SupportsEncryption	logical	(optional) When true, the UI will present the option to connect to the data source using an encrypted connection. This is typically used for data sources with a non-encrypted fallback mechanism (generally ODBC or ADO.NET based sources).

Publish to UI

Similar to the Data Source definition record, the Publish record provides the Power Query UI the information it needs to expose this extension in the Get Data dialog.

Example:

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") }
];

Properties

The following table lists the fields for your Publish record.

Field	Type	Details
ButtonText	list	List of text items. The first item defines the name displayed next to the data source's icon in the Power BI Get Data dialog. The second item (optional) defines the tool tip that will be displayed when the preceding name is moused-over.
Category	text	Where the extension should be displayed in the Get Data dialog. Currently the only category values with special handing are Azure and Database. All other values will end up under the Other category.
Beta	logical	(optional) When set to true, the UI will display a Preview/Beta identifier next to your connector name and a warning dialog that the implementation of the connector is subject to breaking changes.
LearnMoreUrl	text	(optional) Url to website containing more information about this data source or connector.
SupportsDirectQuery	logical	(optional) Enables Direct Query for your extension.
SourceImage	record	(optional) A record containing a list of binary images (sourced from the extension file using the Extension.Contents method). The record contains two fields (Icon16, Icon32), each with its own list. Each icon should be a different size.
SourceTypeImage	record	(optional) Similar to SourceImage, except the convention for many out of the box connectors is to display a sheet icon with the source specific icon in the bottom right corner. Having a different set of icons for SourceTypeImage is optional—many extensions simply reuse the same set of icons for both fields.