How to tell DocumentDB SDK to use camelCase during linq query?

Question

Considering the document { "userName": "user1" } stored in the User collection, and the following User class:

public class User
{
        public string Id { get; set; }
        public string UserName { get; set; }
}

With the following JSON.net settings:

JsonConvert.DefaultSettings = () =>
{
    return new JsonSerializerSettings
    {
       ContractResolver = new CamelCasePropertyNamesContractResolver(),
    };
};

When I query with Linq as such:

var t = _client.CreateDocumentQuery<User>(_collection.SelfLink)
            .Where(u => u.UserName == "user1").AsDocumentQuery().ExecuteNextAsync();

t.Wait();

var users = t.Result;
var user = users.FirstOrDefault();

user is null. Changing the Document to have a pascal casing or the POCO to use a camel casing solves the issue. Of course I do not want any of those as I want my JSON objects and C# objects to be "standarized".

How can I tell the DocumentDB SDK to map my object's property names using camel casing, similar as JSON.net?

Bonesetter

Does this answer solve your issue? It's not exactly a duplicate question, but I believe the published answer covers what you're looking for. – Chinaman

Answer 1

The DocumentDB LINQ provider does not pick up the JsonConvert.DefaultSettings. In general you can use the DefaultSettings to control camelCase, but for those properties you wish to use in a LINQ Where clause must have the name explicitly set using JsonProperty attribute on your DTO.

public class User
{
    public string Id { get; set; }

    [JsonProperty("userName")]
    public string UserName { get; set; }
}

Although a bit tedious and a good source for bugs, it seems to be your only option for now.

Limon

thanks for the answer! this was killing my queries too. For now i'm switching away from LINQ expressions to SQL. – Mandle

A GitHub issue for this: github.com/Azure/azure-documentdb-dotnet/issues/317 – Menzies

Answer 2

In a similar case with Cosmos DB, I was able to set all properties to Camel case for my objects at the class declaration level, as in:

[JsonObject(NamingStrategyType = typeof(CamelCaseNamingStrategy))]
public class User
{
    public string Id { get; set; }

    public string UserName { get; set; }
}

This is how you tell NewtonSoft.Json to use Camel case for serializing.

Venial

This does not work for the CosmosDB DocumentClient. Only controlling the casing per property with JsonProperty("lowerCaseName"). – Distraught

I have tried this solution as well and it doesn't fix the linq queries. – Cinderella

Answer 3

In newer SDK's you can control the linq serialization in the following way:

container.GetItemLinqQueryable<T>(
    linqSerializerOptions: new CosmosLinqSerializerOptions
    {
        PropertyNamingPolicy = CosmosPropertyNamingPolicy.CamelCase
    });

Where container is a Microsoft.Azure.Cosmos.Container.

Dobbins

Answer 4

According to CosmosDB SDK sources if you inherit from CosmosLinqSerializer you can implement SerializeMemberName https://github.com/Azure/azure-cosmos-dotnet-v3/blob/b9b35bb92d5b0c075259a4d78287bff0f66c9861/Microsoft.Azure.Cosmos.Samples/Usage/SystemTextJson/CosmosSystemTextJsonSerializer.cs#L55

And for System.Text.Json you can copy the code above as is. Then you just set PropertyNamingPolicy in your JsonSerializerOptions passed to your Cosmos serializer.

Negris