Example for IEnumerable<T> action as non-blocking, is Incorrect and misleading

[SDP190]

Quote:

Both of the preceding actions are non-blocking as of ASP.NET Core 3.0

However the first example seems to be incorrect, since the first action example calls: _repository.GetProducts()
which returns a List object - as shown in first example on this page - it is a synchronous blocking call to the database returning a List. Only if return type of GetProducts would be IAsyncEnumerable then even if the controller action signature itself would be IEnumerable still the serializer would detect its actually an IAsync and would iterate over it asynchronously.

Is that right?

Quote:

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Document Details

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• ID: fa03501b-5e71-4c18-0269-39babbf9d93c
• Version Independent ID: b51bc104-a6e2-b21f-8362-45cee22e8c22
• Content: Controller action return types in ASP.NET Core web API
• Content Source: aspnetcore/web-api/action-return-types.md
• Product: aspnet-core
• Technology: aspnetcore-webapi
• GitHub Login: @scottaddie
• Microsoft Alias: scaddie

[Rick-Anderson]

@SDP190 See #17259
Moved to Controller action return types Master issue #18092

[SDP190]

Hi, @Rick-Anderson, issue #17259 doesn't refer or solve at all to the issue I described above. I think you didn't understood.

The issue is very simple, again, the statement:

Both of the preceding actions are non-blocking as of ASP.NET Core 3.0

Is simply not true, the first example is blocking! Please change it!

Since GetOnSaleProducts has a call to _repository.GetProducts() which itself is a blocking function -as demonstrated in a preceding code example on that page in the docs- it returns List<Product> not IAsyncAnumerable<Product> or Task<List<Product>> :

So GetOnSaleProducts will also be blocking even in Asp.Net Core 3!

So either you have to clarify that _repository.GetProducts() returns an IAsyncEnumerable<Products> and thus you would have to modify the example code shown in the embedded image, either change the code here in this example so GetOnSaleProducts shouldn't call a blocking function!

[SDP190]

Hi, @Rick-Anderson, this docs is still incorrect even the net6 version.

Since GetProducts seems to return a type List<Product> that means it already blocks (iterates to get all records into memory and only then returns the full List) !
Either change GetProducts example or create another example function that should return IEnumerable<Product>, so assuming the underlying concrete type is asyncable, AspNetCore >3 will buffer its results.

[Rick-Anderson]

We're no longer using a repository for this sample.