对于 OData 和 ASP.NET 内核，URL 太长

Question

I've set up an OData service using ASP.NET Core Web API with OData ( Microsoft.AspNetCore.OData ).

My unbound function has one parameter accepting a string that can be very long: http://localhost:5000/odata/MyFunction(ids='a,b,c,d,e,f') .

This works fine if the length of ids doesn't get too big. However, when passing a too long string, the request fails with HTTP 400 .

I've already tried this - unfortunately, it didn't work.

How do I have to configure the app so that long requests are supported both in production ( Kestrel ) and dev ( IIS Express ) mode?

Answer 1

The problem is not the length of the URL itself. Instead, it is related to OData functions, which lead to a very long URL segment . On Windows, this seems to be limited to 260 characters. So in my case, the URL segment MyFunction(ids='a,b,c,d,e,f') is simply too long.

I found two different approaches:

1. Change a Windows Registry setting ( see here ). I didn't test it, but the comments in the other thread look promising.
2. Use Parameter Aliases .

I've chosen the second approach, so now my URL looks like this: http://localhost:5000/odata/MyFunction(ids=@p1)?@p1='a,b,c,d,e,f' . The neat thing about this is that I hadn't to change anything in my OData configuration - it just works.

After a bit of testing, I reached the maximum query string length. I solved this by introducing a web.config file with the following content:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.webServer>
    <security>
      <requestFiltering>
        <requestLimits maxUrl="20100" maxQueryString="20000" />
      </requestFiltering>
    </security>
  </system.webServer>
  <system.web>
    <httpRuntime maxUrlLength="20100" maxQueryStringLength="20000" />
  </system.web>
</configuration>

The downside of the second approach is that Power BI Desktop doesn't seem to support this easily. I was not able to add a parameter alias within the simple UI when browsing an OData service. However, when creating a Power BI Parameter with the long query string, I was able to compose the OData URL with the Power BI Parameter als Parameter Alias on my own.