HttpClient.GetFromJsonAsync<T> does not handle 204 returned by ASP.NET Core

[dashiell-zhang]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

dotnet/aspnetcore#43608

This question has been closed, but the problem itself has not been solved. When the remote interface returns 204, because there is no information in the content, calling this method will directly trigger an exception. I personally think that a more reasonable solution here is to return null instead of throwing an exception directly.

At present, I have to wrap it myself, but I feel that this is a very strange behavior

        public static async Task<TValue?> GetFromJsonAsync<TValue>(this HttpClient client, string requestUri)
        {
            var response = await client.GetAsync(requestUri);
            if (response.StatusCode == HttpStatusCode.NoContent)
            {
                return default;
            }
            return await response.Content.ReadFromJsonAsync<TValue>(jsonToObjectOptions);
        }

Expected Behavior

When the status code is 204 or the Content is empty, Null is returned directly instead of an exception.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

9.0.201

Anything else?

No response

[gfoidl]

This issue should be moved to runtime, as it's for HttpClient and related to ASP.NET Core per se (the HTTP 204 can also come from other server implementations).

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[antonfirsov]

Even though this might make it ASP.NET interop easier for some scenarios, special-casing 204 and returning null would go against other scenarios when an exception is more desired. This would be a breaking change in those cases.

[dashiell-zhang]

When it is clear that 204 means null, it seems that this method should return Null, which is a normal logic. At present, it is directly abnormal, which always feels a bit strange.