mardi 14 mars 2017

Using GraphQL in your Windows Application part II - using mutations [UWP,NET,GraphQL]

In this article we are going to see how we can do a Mutation in GraphQL in your .NET app, you will be able to find more documentation about mutations here: http://graphql.org/learn/queries/

We will be using the same endpoints and example as in the previous article:
Using GraphQL in your Windows Application part I [UWP,NET,GraphQL]

Just like the previous article related to querying GraphQL, you will need a text file that will hold a JSON mutation query as follow:

mutation($input: FavBookInput!){
  favoriteBook(input:$input){
    status
    clientMutationId
  }
}

Next we will need to create a Class what will hold the variables that we will pass in our query:

namespace GraphQL.QlFiles.M
{
    public class QueryAddToFavBooksMutationModel
        {
        public BookInput input { get; set; }
    }
    public class BookInput
    {
        public string bookXid { get; set; }
    }
}

Here are the string const that we will be using:

 public const string GrapgQL_PARAM_Query_and_Variables_To_CALL = "query={0}&variables={1}";
 public const string GRAPHQL_URL_BASE = "https://graphql.api.abcde.com/";
 public const string MyMutationQueryCallFile = "ms-appx:///QlFiles/M/AddToFavBooks.txt";

Doing a mutation on GraphQL is very much like doing a classic GET HTTP GraphQL query but you also need to pass variable in the query.  You will need to intenciante the QueryAddToFavBooksMutationModel class with the correct value so that you can add the correct book to your favorites.  Next you will convert the class to JSON and pass this it to your query as follows:

 private async void GraphQLMutationQuery()
        {
            //prepartion the variables that will be sent for the get query
            var myMutation = new QueryAddToFavBooksMutationModel()
            {
                input = new BookInput()
                {
                    bookXid = "ABC"
                }
            };

            //getting ou file
            var queryParams = await FileIOReaderHelper.ReadFromDefaultFileAsync(MyMutationQueryCallFile);

            //serializing our class to json so that we can send it in the GET call.
            string Variables = JsonConvert.Serialize(myMutation);

            var paramsToCall = String.Format(GrapgQL_PARAM_Query_and_Variables_To_CALL,
                            WebUtility.UrlEncode(queryParams),
                            WebUtility.UrlEncode(Variables)
                        );

            //creating our query
            var urlQuery = String.Format("{0}?{1}", GRAPHQL_URL_BASE, paramsToCall);

            //now you can do your http call 
            var response = await HttpClient.SendAsync(urlQuery);
        }





NAd there you have it you can now do mutations on GraphQL. This could be greatly improved, however for our example this gets the job done.

Happy coding.

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