Variables

You can pass variables received from the client to the execution engine by using the Variables property.

See the official GraphQL documentation on variables

Here is what a query looks like with a variable:

graphql

query DroidQuery($droidId: String!) {
  droid(id: $droidId) {
    id
    name
  }
}

Here is what this query would look like as a JSON request:

json

{
 "query": "query DroidQuery($droidId: String!) { droid(id: $droidId) { id name } }",
 "variables": {
   "droidId": "1"
 }
}

Call .Deserialize<GraphQLRequest>() to parse a JSON request to provide it to the DocumentExecuter:

csharp

var requestJson = /* request as shown above */;
var request = new GraphQLSerializer().Deserialize<GraphQLRequest>(requestJson);

var result = await schema.ExecuteAsync(options =>
{
  options.Query = request.Query;
  options.OperationName = request.OperationName;
  options.Variables = request.Variables;
  options.Extensions = request.Extensions;
});

If you need to parse the variables separately from the query, you can call .Deserialize<Inputs>() to parse a JSON-formatted variables string to an Inputs class suitable for passing to the DocumentExecuter:

csharp

var variablesJson = /* get from request */;
var inputs = new GraphQLSerializer().Deserialize<Inputs>(variablesJson);

await schema.ExecuteAsync(options =>
{
  options.Query = "...";
  options.Variables = inputs;
});

Please note that you will need either the GraphQL.SystemTextJson or GraphQL.NewtonsoftJson nuget package to run the above code, with the appropriate using statement.

When using dependency injection, you will typically register the serializer via .AddSystemTextJson() or .AddNewtonsoftJson() in your DI configuration code, and then pull in instances of IGraphQLTextSerializer, ISchema and IDocumentExecuter, resulting with code more similar to the following:

csharp

Task<string> ExecuteAsync(string request, CancellationToken cancellationToken = default)
{
  var request = _serializer.Deserialize<GraphQLRequest>(request);
  var result = await _documentExecuter.ExecuteAsync(options =>
  {
    options.Schema = _schema;
    options.Query = request.Query;
    options.OperationName = request.OperationName;
    options.Variables = request.Variables;
    options.Extensions = request.Extensions;
    options.CancellationToken = cancellationToken;
  });
  var response = _serializer.Serialize(result);
  return response;
}

You can also use the .Read<T>() and .Write() methods of the serializer for Stream-based asynchronous serialization and deserialization.