Strongly-typed GraphQL Client solution

.Intructions.md

This gist demonstrates a solution to generating a strongly-typed client for a GraphQL service.

1. Create a .csproj project (e.g. MyCompany.GraphQL.Queries)
2. Add some queries using .graphql files
3. Add the .ps1 script above
4. Install quicktype
5. Add a reference to Newtonsoft.Json to the project (required by the generated query files, though that may change in the future to System.Text.Json)
6. Add a client wrapper that can utilise the query types and deserialize into them (see TypedGraphQLClient.cs)
7. Use it elsewhere.

generate-types.ps1

Write-Host "Downloading the latest schema from localhost... " -NoNewline
quicktype --http-method "POST" --graphql-introspect http://localhost:33012/graphql --graphql-schema myCompany.gqlschema
Write-Host "Done."

Write-Host "Finding *.graphql files to generate types for... " -NoNewline
$queries = Get-ChildItem -Path .\ -Filter *.graphql -Recurse -File -Name
$queriesLength = $queries.Length
Write-Host "Done. $queriesLength queries found."

$queries | ForEach-Object {
    $queryName = [System.IO.Path]::GetFileNameWithoutExtension($_)
    $namespace = 'MyCompany.GraphQL.Queries.' + $queryName
    $queryPath = $queryName + '\' + $queryName + '.graphql'
    $outPath = $queryPath.replace('.graphql', '.cs')

    Write-Host "Generating type for $queryName... " -NoNewline
    quicktype --src-lang graphql --lang csharp --array-type list --density dense --number-type decimal --graphql-schema myCompany.gqlschema `
        --namespace $namespace $queryPath --out $outPath
    Write-Host "Done."
}

Write-Host "Deleting the schema... " -NoNewline
Remove-Item myCompany.gqlschema
Write-Host "Done."

exit

TypedGraphQLClient.cs

using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;
using MyCompany.GraphQL.Queries;
using MyCompany.GraphQL.Queries.ArticleTileQuery;
using GraphQL.Client;
using GraphQL.Common.Request;
using GraphQL.Common.Response;
using Newtonsoft.Json;

namespace GraphQLService.Client
{
    public class TypedGraphQLClient : GraphQLClient, IAutoGuruGraphQLClient
    {
        public TypedGraphQLClient(HttpClient httpClient)
            : base(httpClient)
        {

        }

        public async Task<TResult> ExecuteAsync<TResult>(GraphQLRequest request)
        {
            var graphResponse = await PostAsync(request);

            var responseJson = JsonConvert.SerializeObject(new
            {
                data = graphResponse.Data,
                errors = graphResponse.Errors
            });

            var methodInfo = typeof(TResult).GetMethod("FromJson");
            if (methodInfo != null)
            {
                return (TResult)methodInfo.Invoke(null, new object[] { responseJson });
            }

            return default;
        }
        
        // You could add specific methods to specific typed queries here if desired as shorthand.
    }
}