GraphQL .NET上部分更新突变的空字段

Question

在工作中,我们在数据层和graphql-dotnet上使用EFCore来管理API请求,我在使用GraphQL突变更新一些大对象时遇到问题.当用户在模型上发送部分更新时,我们希望仅在数据库中更新实际由突变更改的字段.我们遇到的问题是,当我们直接将输入映射到实体时,有些字段被有目的地传递为null,或者根本没有在字段上指定字段,我们将属性值作为null.这样我们就无法将更改发送到数据库,否则我们会错误地将一堆字段更新为null.

因此,我们需要一种方法来识别哪些字段是在变异中发送的,只是更新它们.在JS中,这是通过检查属性值是否未定义来实现的,如果值为null,我们知道它是故意传递为null.

我们一直在考虑的一些解决方法是使用Dictionary上的反射来仅更新指定的字段.但我们需要将反射传播到每一个突变.另一个解决方案是对我们模型上的每个可空属性都有一个isChanged属性,并在引用的属性setter上更改ir,但是...... cmon ...

我提供了一些代码作为这种情况的例子如下:

人类:

public class Human
{
    public Id { get; set; }
    public string Name { get; set; }
    public string HomePlanet { get; set; }
}

GraphQL类型:

public class HumanType : ObjectGraphType<Human>
{
    public HumanType()
    {
        Name = "Human";
        Field(h => h.Id).Description("The id of the human.");
        Field(h => h.Name, nullable: true).Description("The name of the human.");
        Field(h => h.HomePlanet, nullable: true).Description("The home planet of the human.");
    }
}

输入类型:

public class HumanInputType : InputObjectGraphType
    {
        public HumanInputType()
        {
            Name = "HumanInput";
            Field<NonNullGraphType<StringGraphType>>("name");
            //The problematic field
            Field<StringGraphType>("homePlanet");
        }
    }

人类突变:

/// Example JSON request for an update mutation without HomePlanet 
/// {
///   "query": "mutation ($human:HumanInput!){ createHuman(human: $human) { id name } }",
///   "variables": {
///     "human": {
///       "name": "Boba Fett"
///     }
///   }
/// }
///
public class StarWarsMutation : ObjectGraphType<object>
{
    public StarWarsMutation(StarWarsRepository data)
    {
        Name = "Mutation";

        Field<HumanType>(
            "createOrUpdateHuman",
            arguments: new QueryArguments(
                new QueryArgument<NonNullGraphType<HumanInputType>> {Name = "human"}
            ),
            resolve: context =>
            {
                //After conversion human.HomePlanet is null. But it was not informed, we should keep what is on the database at the moment
                var human = context.GetArgument<Human>("human");
                //On EFCore the Update method is equivalent to an InsertOrUpdate method
                return data.Update(human);
            });
    }
}

Answer 1

您可以使用JsonConvert.PopulateObjectNewtonsoft Json 库。在突变解析器上GetArgument，我没有使用我的类型，而是使用GetArgument<dynamic>它并序列化它，JsonConvert.SerializeObject然后通过调用JsonConvert.PopulateObject我能够仅更新通知的字段。

public StarWarsMutation(StarWarsRepository data)
{
    Name = "Mutation";

    Field<HumanType>(
        "createOrUpdateHuman",
        arguments: new QueryArguments(
            new QueryArgument<NonNullGraphType<HumanInputType>> {Name = "human"}
        ),
        resolve: context =>
        {
            //After conversion human.HomePlanet is null. But it was not informed, we should keep what is on the database at the moment
            var human = context.GetArgument<dynamic>("human");
            var humanDb = data.GetHuman(human["id"]);
            var json = JsonConvert.SerializeObject(human);
            JsonConvert.PopulateObject(json, humanDb);
            //On EFCore the Update method is equivalent to an InsertOrUpdate method
            return data.Update(humanDb);
        });
}