EF Core“InvalidOperationException: Include has been used on non entity queryable”用於導航屬性，即使在顯式包含之后

Question

我創建了一個使用以下包的示例項目 -

1. GraphQL
2. GraphQL.EntityFramework
3. System.Linq.Dynamic.Core

這里的想法是轉換在 GraphQL 查詢中完成的選擇並將其傳遞到 EntityFramework 上，以免過度獲取查詢中未要求的列。 為此，我使用System.Linq.Dynamic.Core在字符串上傳遞表單中的Select表達式。 我已經看到 EntityFramework github repo 上存在一個問題，用於獲取導航屬性，其中指出 include 是必須的，如這里所討論的。 之后，我在進行Select之前包含了所需的導航屬性，但由於某種原因它抱怨以下錯誤 -

GraphQL.ExecutionError: Error trying to resolve customers.
---> System.InvalidOperationException: Include has been used on non entity queryable.
at Microsoft.EntityFrameworkCore.Query.Internal.NavigationExpandingExpressionVisitor.ProcessInclude(NavigationExpansionExpression source, Expression expression, Boolean thenInclude)
at Microsoft.EntityFrameworkCore.Query.Internal.NavigationExpandingExpressionVisitor.VisitMethodCall(MethodCallExpression methodCallExpression)
at System.Linq.Expressions.MethodCallExpression.Accept(ExpressionVisitor visitor)
at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
at Microsoft.EntityFrameworkCore.Query.Internal.NavigationExpandingExpressionVisitor.Expand(Expression query)
at Microsoft.EntityFrameworkCore.Query.QueryTranslationPreprocessor.Process(Expression query)
at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)
at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)
at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)
at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass12_0`1.<ExecuteAsync>b__0()
at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func`1 compiler)
at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteAsync[TResult](Expression query, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1.GetAsyncEnumerator(CancellationToken cancellationToken)
at System.Runtime.CompilerServices.ConfiguredCancelableAsyncEnumerable`1.GetAsyncEnumerator()
at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
at GraphQL.EntityFramework.EfGraphQLService`1.<>c__DisplayClass26_0`2.<<BuildQueryField>b__0>d.MoveNext() in C:\\projects\\graphql-entityframework\\src\\GraphQL.EntityFramework\\GraphApi\\EfGraphQLService_Queryable.cs:line 130
at GraphQL.Instrumentation.MiddlewareResolver.Resolve(ResolveFieldContext context)
at GraphQL.Execution.ExecutionStrategy.ExecuteNodeAsync(ExecutionContext context, ExecutionNode node)

這是失敗的代碼

public class QueryTest : QueryGraphType<TestDBContext>
{
    public QueryTest(IEfGraphQLService<TestDBContext> graphQlService) :
        base(graphQlService)
    {
        Name = "Query";
        AddQueryField(
            name: "customers",
            // the next line is failing
            resolve: context => context.DbContext.Customers.Include(x => x.Orders).Select<Customer>(GetSelect(context.SubFields))                
        );
        AddQueryField(
            name: "orders",
            resolve: context => context.DbContext.Orders.Include(x => x.Customer).Select<Order>(GetSelect(context.SubFields))
        );
    }

    private string GetSelect(IDictionary<string, Field> subfields) => $"new({string.Join(",", GetSelectedColumns(subfields))})";

    private IEnumerable<string> GetSelectedColumns(IDictionary<string, Field> subfields)
    {
        foreach (var item in subfields)
        {
            if (item.Value.SelectionSet.Children.Count() > 0)
            {
                continue;
            }
            yield return item.Key;
        }
    }
}

當我發出以下 GraphQL 查詢時

query {
  customers {
    customerName
    orders {
      orderID
      orderDate
    }
  }
}

完整的代碼示例托管在github 上，而不是粘貼在這里，因為它太長而無法閱讀。 任何幫助將不勝感激。

Answer 1

您是否嘗試過這個項目： https : //github.com/StefH/GraphQL.EntityFrameworkCore.DynamicLinq ？

通過此項目，您可以輕松地將 EF 實體中的所有屬性公開為 GraphQL 查詢上的可搜索字段。

例如，參見https://github.com/StefH/GraphQL.EntityFrameworkCore.DynamicLinq/tree/master/examples/MyHotel