Custom data connector and Windows authentication

thoBA — Mon, 14 Sep 2020 08:29:15 GMT

Hi,

I am trying to build a custom data connector that lets users navigate a folder structure on the local machine/network and import selected Excel Tables into PBI. The below example line "source = Excel.Workbook(File.Contents(url), null, true)" works without a problem using Windows authentication with "Use my current credentials" when executed directly in a Power BI Desktop query. However, when executed from within my custom data connector I receive the error message "Please specify how to connect" in the Connection dialog in PBI:

[DataSource.Kind="PQExtension1", Publish="PQExtension1.Publish"]
shared PQExtension1.File = (path as text) as table =>
let
source = Excel.Workbook(File.Contents(path), null, true)
in
source;

Data Source Kind is configured like this:

PQExtension1 = [ Authentication = [
Windows = [
// This key brings up the 'Use current credentials' and 'User Name' etc. edit boxes in the credential dialog in PBI
SupportsAlternateCredentials = true ] ],
Label = Extension.LoadString("DataSourceLabel") ];

Note, that it fails with the same error message also if I supply a user name and password instead for authentication.

I have also tried to send the current credentials to the File.Contents method File.Contents(path, Extension.CurrentCredential()). But this only results in the error "2 arguments supplied to a function that only expects one" - even though the documentation clearly states that File.Contents can accept a record as a second parameter.

What am I missing? I would be realy grateful if somebody could help me out with this authentication problem!

Edit :: I found the following text in the documentation at https://docs.microsoft.com/en-us/power-query/handlingdataaccess#data-source-kind:

"Currently, a limited set of data source functions have been enabled to support extensibility.

So the basic data access functions, such as File.Contents(), are not supported for data connectors...?

Re: Custom data connector and Windows authentication

Anonymous — Wed, 10 Mar 2021 10:45:21 GMT

I'm facing a similar problem , only in my case I using Xml instead of Excel.

When testing my connector in Visual Studio, the "M Query Output" Error tab show this error:

"Credentials are required to connect to the <ConnectorName> source. (Source: from c:\temp\file.xml to <ConnectorName>

When testing the connector in Power BI, getting this error:

"Please specify how to connect"

This thread is 7 months old. Please advise...

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Custom data connector and Windows authentication

Re: Custom data connector and Windows authentication