Replace the default Azure Function Json pascalCase formatter with camelCase

I use dotnet-isolated function runtime and by default it is using ObjectSerializer to convert objects to Json. The response is formatted with PascalCase which is doesn't look as natural Json naming style. Let's see how we can format it to camelCase and remove nullables.

{
    "Errors": []
}

I didnt find a way how to configure the serializer for the function on global level, however it quite simple to set the serilizer while writing the response.

The following code example creates a new response and writes an object

var response = req.CreateResponse(HttpStatusCode.Created);
await response.WriteAsJsonAsync(new MyClass());

First, ObjectSerializer is one of the optional parameters for the WriteAsJsonAsync extension method, which can be replaced with one from Newtonsoft.Net. ObjectSerializer is part of Azure.Core.Serialization to user its Newtonsoft.Net implementation, you have to install Microsoft.Azure.Core.NewtonsoftJson package.

Secondly, you need to create settings for JsonSerializer:

var s = new JsonSerializerSettings
{
    NullValueHandling = NullValueHandling.Ignore,
    ContractResolver = new CamelCasePropertyNamesContractResolver()
};

var serializer = new NewtonsoftJsonObjectSerializer(s);

And the last one, use defined serializer while writing the response

await response.WriteAsJsonAsync(new MyClass(), serializer);

The response is formatted with camelCase

{
    "errors": []
}