[feature/netcore] Nested $expand not working

[techniq]

When attempting to expand more than 1 level deep the property is added to the model but set to null. I also do not see any mention of it in the EFCore sql query. Other operators seem to work (at least $select)

Assemblies affected

• 7.0.0-Nightly201801081323

Reproduce steps

Attempt to expand more than 1 level deep. For example:

• http://localhost:5000/odata/Employees?$expand=Supervisor($expand=Position)

Expected result

{
  "@odata.context": "http://localhost:5000/odata/$metadata#Employees",
  "value": [
    {
      ...
      "Supervisor": {
        ...
        "Position": { ... } // Populated with Position properties
      }
    },
    ...
  ]
}

Actual result

{
  "@odata.context": "http://localhost:5000/odata/$metadata#Employees",
  "value": [
    {
      ...
      "Supervisor": {
        ...
        "Position": null
      }
    },
    ...
  ]
}

Additional detail

I've attempted to set [EnableQuery(MaxExpansionDepth = 3)] on the endpoint but resulted in no change.

[robward-ms]

@techniq - Can you provide the code that builds the model?

[robward-ms]

@techniq - Can you provide the code that builds the model?

[techniq]

@robward-ms Actually, I think I have more details that can help (after some more testing).

Currently, this still returns the null Position as indicated above:

[EnableQuery()]
public IQueryable<Employee> Get()
{
    return DbContext.Employees;
}

but using the following fixes this problem

[HttpGet]
public IActionResult Get(ODataQueryOptions<Employee> queryOptions)
{
    var querySettings = new ODataQuerySettings()
    {
        // Workaround for: https://github.com/aspnet/EntityFrameworkCore/issues/10721
        HandleNullPropagation = HandleNullPropagationOption.False
    };

    var query = queryOptions.ApplyTo(DbContext.Set<Employee>(), querySettings);
    return Ok(query);
}

Removing HandleNullPropagation = HandleNullPropagationOption.False shows the same issues as [EnableQuery], but adding it fixes this issue (and dotnet/efcore/issues/10721). I also thought it fixed dotnet/efcore#10721, but after more testing, that looks to be fixed even using [EnableQuery()] now (I'm using 7.0.0-Nightly201802211312)

[robward-ms]

@techniq - On EFCore?

There is some code missing to set NullPropgation for EFCore, I have it in the EFCore investigation branch: https://github.com/robward-ms/WebApi/blob/0ba1ddca056555a1aef556e6493c57b29dcef2ed/src/Microsoft.AspNet.OData.Shared/Query/HandleNullPropagationOptionHelper.cs

[techniq]

@robward-ms yes, 2.0.1

[techniq]

Resolved, thanks @robward-ms

[urko-b]

Does anyone knows why I have to explicitly add NavigationParameters when I try to query my API with $Expand. In Framework 4.6 API with OData V4 I only had to add the reserved word "Virtual" to each navigation property.

Those images are from my AspNetCore.OData API

Here, with postman I try to get the user information with it's navigation property

Here is the result if i do not explicitly add the navigation property names in the controller method: