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Hi All,
I'm building a custom connector to utilize an API. I'm attempting to handle pagination, but am having a hard time. Here's what I'm trying to do:
I'm trying to use List.Generate because it appears to be my best option for a Do...While/Until loop. Here's what I have:
Main = (Scope) => let HasContToken = (responseHeaders) as logical => if (Record.HasFields(responseHeaders, {"Continuation"})) then true else false, GetPage = (Scope, ContinuationToken) => let url = api_source_uri & Scope, RawData = Web.Contents(url, [ Headers = [ #"Continuation" = ContinuationToken ]]) in RawData, Pages = List.Generate(() => Web.Contents(api_source_uri & Scope), each HasContToken(Value.Metadata(_)[Headers]), each GetPage(Scope, Value.Metadata(_)[Headers][Continuation])), Pages_JSON = Json.Document(Pages), Table = Table.FromList(Pages_JSON, Splitter.SplitByNothing()) in Table;
I receive this error when trying to run this code: "The parameter is expected to be of type Text.Type or Binary.Type."
I don't know which parameter this is referring to, but I assume it is related to how I've set up List.Generate. Any help is greatly appreciated.
Thank you!
Solved! Go to Solution.
Hi @v-xicai ,
Thank you for your response. The issue was indeed related to null values being returned in subsequent calls. However, this was because the API I'm using required an "accept" header to be included, which I had overlooked. Below is my updated code:
let HasContToken = (responseHeaders) as logical => if (Record.HasFields(responseHeaders[Headers], {"Continuation"})) then true else false, GetPage = (Scope, ContinuationToken) => let RawData = Web.Contents(api_source_uri, [ RelativePath = "/reporting/v1/" & Scope, Query = [ limit = "1000" ], Headers = [ #"Continuation" = ContinuationToken, accept = "application/json" ]]) in RawData, Pages = List.Generate(() => Web.Contents(api_source_uri, [ RelativePath = "/reporting/v1/" & Scope, Headers = [ accept = "application/json" ], Query = [ limit = "1000" ]]), each HasContToken(Value.Metadata(_)), each GetPage(Scope, Value.Metadata(_)[Headers][Continuation])), JSON = List.Transform(Pages, (_) => Json.Document(_)), List = List.Combine(JSON), Table = Table.FromList(List, Splitter.SplitByNothing(), null, null, ExtraValues.Error) in Table;
Hi @ChadC ,
When combining files, be sure to choose "Skip files with errors." see more: https://www.sqlchick.com/entries/2018/5/6/querying-data-in-azure-data-lake-store-with-power-bi.
There may be some nulls in your dataset which generated the error when the parsing was attempted, replace the null values with an empty structure "<div></div>" which was then parsed . See The parameter is expected to be of type Text.Type or Binary.Type.
If you still have this issue for Power BI, you'd better create a support ticket in Power BI Support , Scroll down and click "CREATE SUPPORT TICKET", to get further help.
Best Regards,
Amy
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
Hi @v-xicai ,
Thank you for your response. The issue was indeed related to null values being returned in subsequent calls. However, this was because the API I'm using required an "accept" header to be included, which I had overlooked. Below is my updated code:
let HasContToken = (responseHeaders) as logical => if (Record.HasFields(responseHeaders[Headers], {"Continuation"})) then true else false, GetPage = (Scope, ContinuationToken) => let RawData = Web.Contents(api_source_uri, [ RelativePath = "/reporting/v1/" & Scope, Query = [ limit = "1000" ], Headers = [ #"Continuation" = ContinuationToken, accept = "application/json" ]]) in RawData, Pages = List.Generate(() => Web.Contents(api_source_uri, [ RelativePath = "/reporting/v1/" & Scope, Headers = [ accept = "application/json" ], Query = [ limit = "1000" ]]), each HasContToken(Value.Metadata(_)), each GetPage(Scope, Value.Metadata(_)[Headers][Continuation])), JSON = List.Transform(Pages, (_) => Json.Document(_)), List = List.Combine(JSON), Table = Table.FromList(List, Splitter.SplitByNothing(), null, null, ExtraValues.Error) in Table;
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