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petrbroz's avatar
petrbroz
New Member
1 year ago
Solved

Functions in Navigation Tables for Power BI Custom Connector

Hi everyone,   I'm building a custom data connector for Power BI, trying to expose a navigation table with a couple of functions, following this specific code sample: https://github.com/microsoft/D...
Need Help
  • Anonymous's avatar
    Anonymous
    1 year ago

    Hi petrbroz ,

    Yes, this is the expected behavior when a function in a custom connector does not require any parameters. When you click the function in the navigation pane, Power BI will display a message indicating that no parameter values are specified because the function does not need any input from the user. This is a standard message to show that there are no parameters to pass for the function when you invoke it. 

    Best Regards

Anonymous's avatar
Anonymous
Not applicable
1 year ago

Hi petrbroz ,

The message "No parameter values specified" typically appears when a function expects parameters but none are provided. Please check if the function define any unexpected parameter, update the codes below for the function TestFunction and TestFunctionType:

 

  TestFunction = () as table => 
    let 
        result = #table({"Column1", "Column2"}, {{"Test Function A", "Default Message"}}) 
    in 
        result;
TestFunctionType = type function () as table meta
    [
        Documentation.Name = "Test Function",
        Documentation.LongDescription = "Function description..."
    ];

 

Best Regards

  • petrbroz's avatar
    petrbroz
    New Member
    1 year ago

    Thank you for the suggestion Anonymous. Unfortunately that doesn't solve the issue. Please note that the function I'm trying to access in Power BI is AnotherFunction.Contents which is already without any parameters.

     

    Btw. I've also tested the official sample: https://github.com/microsoft/DataConnectors/blob/master/samples/NavigationTable without any modifications, and I get the same message, so I'm wondering if this is the expected behavior?

     

    • Anonymous's avatar
      Anonymous
      Not applicable
      1 year ago

      Hi petrbroz ,

      Yes, this is the expected behavior when a function in a custom connector does not require any parameters. When you click the function in the navigation pane, Power BI will display a message indicating that no parameter values are specified because the function does not need any input from the user. This is a standard message to show that there are no parameters to pass for the function when you invoke it. 

      Best Regards

      • petrbroz's avatar
        petrbroz
        New Member
        1 year ago

        Thank you Anonymous. After some more research I've found that Power BI shows a slightly different message depending on whether the function accepts any parameters:

        • If the function accepts no parameters, Power BI shows "No parameter values specified"
        • If the function accepts parameters (doesn't matter whether it's documented or not), Power BI shows "Parameter value not specified"

        I think the naming is a bit misleading. Also, it would be nice if the behavior was:

        • If the function accepts no parameters, Power BI shows the results of calling the function
        • If the function accepts parameters, Power BI shows UI to input these parameters (just like it does for the top level function), and then shows the results based on the provided inputs

         

         .

         

        Source code:

         

        [Version = "1.0.0"]
section TestConnector;

TestConnector = [
    Authentication = [
        Anonymous = []
    ]
];

TestConnector.Publish = [
    Beta = true,
    Category = "Other",
    ButtonText = {"Test Connector", "Test Connector"},
    LearnMoreUrl = "https://powerbi.microsoft.com/"
];

[DataSource.Kind="TestConnector", Publish="TestConnector.Publish"]
shared TestConnector.Contents = () =>
    let
        records = {
            [
                Name = "Function with no params",
                Key = "f1",
                Data = FunctionWithNoParams,
                ItemKind = "Function",
                ItemName = "Function",
                IsLeaf = true
            ],
            [
                Name = "Function with params (undocumented)",
                Key = "f2",
                Data = FunctionWithParams,
                ItemKind = "Function",
                ItemName = "Function",
                IsLeaf = true
            ],
            [
                Name = "Function with params (documented)",
                Key = "f3",
                Data = Value.ReplaceType(FunctionWithParams, FunctionWithParamsType),
                ItemKind = "Function",
                ItemName = "Function",
                IsLeaf = true
            ]
        }
    in
        NavigationTable(records);

FunctionWithNoParams = () as table =>
    #table(
        {"Column"},
        {{"Foo"}}
    );

FunctionWithParams = (name as text) as table =>
    #table(
        {"Name"},
        {{name}}
    );

FunctionWithParamsType = type function (
    name as (type text meta [
        Documentation.FieldCaption = "My Param Name",
        Documentation.FieldDescription = "Parameter description..."
    ])
) as table meta [
    Documentation.Name = "My Function Name",
    Documentation.LongDescription = "Function description..."
];

NavigationTable = (records as list) as table =>
    let
        _table = Table.FromRecords(records),
        tableType = Value.Type(_table),
        newTableType = Type.AddTableKey(tableType, {"Key"}, true) meta 
        [
            NavigationTable.NameColumn = "Name",
            NavigationTable.DataColumn = "Data",
            NavigationTable.ItemKindColumn = "ItemKind",
            Preview.DelayColumn = "ItemName",
            NavigationTable.IsLeafColumn = "IsLeaf"
        ]
    in
        Value.ReplaceType(_table, newTableType);

         

        Since you say this is the expected behavior, I'll accept your solution, and I'll submit my suggestions in https://ideas.fabric.microsoft.com. Thank you!