Model with Custom Attribute without PropertyName throws error

[kylednoland]

Repro Steps

Add an OpenApiResponseWithBody on a Function with a response with type that is decorated with a custom attribute without the PropertyName field populated.

Example of Function Attribute

 [OpenApiResponseWithBody(HttpStatusCode.OK, "application/json", typeof(Thing), Summary = "A returned Thing")]

Example of referenced class that produces the error

    public class Thing
    {
        [JsonProperty(Required = Required.Default)]
        public string Text { get; set; }
    }

Currently, the Function will throw an error when generating an OpenAPI document with a response: System.Private.CoreLib: Exception while executing function: RenderSwaggerDocument. System.Private.CoreLib: Value cannot be null. Parameter name: key..

Potential Solution

In PropertyInfoExtensions.cs add a null check for when there is no PropertyName and return the element.Name property instead such as:

        public static string GetJsonPropertyName(this PropertyInfo element)
        {
            if (element.ExistsCustomAttribute<JsonPropertyAttribute>())
            {
                var name = element.GetCustomAttribute<JsonPropertyAttribute>().PropertyName;

                if (name == null)
                {
                    return element.Name;
                }

                return name;

            }

            return element.Name;
        }

[justinyoo]

@kylednoland Thanks for raising the issue! Can you try [JsonRequired] for your case, instead of [JsonProperty(Required = Required.Default)]

Even if it doesn't solve the issue with the current version, it's sorted out on v3, which will be released soon. Please have a try and let us know.

[kylednoland]

Hey @justinyoo, thanks for the quick response! I switched out the JsonProperty for JsonRequired and it seems to have resolved the issue using my example from above. With v3 coming soon would it be worth it to fix this to maintain v2?

[justinyoo]

@kylednoland This has been fixed on v3.0.0

[kylednoland]

Thanks for the v3 updates @justinyoo! I just updated my code with the latest NuGet package update for version 3.0.0 and I'm still unfortunately seeing this same error. Updating models to use [JsonRequired] rather than [JsonProperty(Required = Required.Default)] does seem to still fix the issue (as in v2).

[kylednoland]

Looking at the updated PropertyInfoExtensions.cs file it looks like it would need to check if the PropertyName value is null in addition to the check if the custom property exists in order to resolve this issue.

[justinyoo]

@kylednoland Re-open the issue to have a look. Could you please provide me with steps to repro?

I have a sample model like this:

AzureFunctions.Extensions/samples/Aliencube.AzureFunctions.FunctionApp.Models/DummyResponseModel.cs

Lines 41 to 42 in c53adaf

	[JsonProperty("CapitalisedJsonPropertyRequiredValue", Required = Required.DisallowNull)]
	public string JsonPropertyRequiredValue { get; set; } = "hello world";

The Required.Default enum value doesn't mean the property is required, by the way. 🤔 It only sees Required.Always and/or Required.DisallowNull to recognise as required.

[kylednoland]

To reproduce you would need a model like the following:

[JsonProperty(Required = Required.DisallowNull)]
public string JsonPropertyUnNamedValue { get; set; } = "hello world";

[kylednoland]

Issue fixed in PR #103