Query generation issues when using ODATA

Worked through a few more of my ODATA examples, I’ve discovered a few further issues with query generation when using Microsoft ODATA WebApi (https://github.com/OData/WebApi) for .net core 3.1. I’m using a build from commit 8cd544b for linq2db in the master branch with the fix for #2070

Sample project here: https://github.com/djkunkel/linq2db-aggregate-odata-sample

The following requests fails to generate SQL:

Without orderby:

/odata/People?$apply=groupby((Title),aggregate(YearsExperience with countdistinct as Test))

With orderby:

/odata/People?$apply=groupby((Title),aggregate(YearsExperience with sum as TotalExperience))&$orderby=TotalExperience
/odata/People?$apply=groupby((Title),aggregate(YearsExperience with min as Test))&$orderby=Test
/odata/People?$apply=groupby((Title),aggregate(YearsExperience with max as Test))&$orderby=Test
/odata/People?$apply=groupby((Title),aggregate(YearsExperience with average as Test))&$orderby=Test
/odata/People?$apply=groupby((Title),aggregate(YearsExperience with countdistinct as Test))&$orderby=Test

The following cases do work for reference:

/odata/People?$apply=groupby((Title),aggregate(YearsExperience with sum as Test))
/odata/People?$apply=groupby((Title),aggregate(YearsExperience with average as Test))
/odata/People?$apply=groupby((Title),aggregate(YearsExperience with min as Test))
/odata/People?$apply=groupby((Title),aggregate(YearsExperience with max as Test))
/odata/People?$apply=groupby((Title),aggregate($count as NumPeople))&$orderby=NumPeople
/odata/People?$apply=groupby((Title),aggregate($count as NumPeople))&$count=true
/odata/People?$apply=filter(Title eq 'Engineer' or Title eq 'QA')/groupby((Title),aggregate($count as NumPeople))&$count=true
/odata/People?$apply=groupby((Office/Name),aggregate($count as NumPeople))&$count=true
/odata/People?$apply=filter(Title eq 'QA')/groupby((Office/Id,Office/Name),aggregate($count as NumPeople))&$count=true&$orderby=NumPeople desc
/odata/people?$expand=Office

Thank you for this project again!

[sdanyliv]

@djkunkel, version 2.9.7 will be released on Thursday. Dsitinct.Count queries will work but hey have non optimal SQL generation. If you expect COUNT (DISTICT x) - pity that it is not ready yet but i’m working on it.

[sdanyliv]

I see, one team creates something not compatible with others. But I saw in OData code hacks for each EF version. Workarounds can not help if there are no test cases on EF side.

Anyway OData team are also clever guys, they have defined dynamic aggregation without generating run-time classes on the fly. I was surprised with the idea to just inject into JSON serialization with specially prepared classes.