// Transform db => db.Entities.Where(args) into args => db => db.Entities.Where(args)
public static void AddQuery <TContext, TEntity>(this GraphQLSchema <TContext> context, string name, Expression <Func <TContext, TEntity> > queryableGetter)
{
var queryables = typeof(TEntity).GetInterfaces().Concat(new[] { typeof(TEntity) }).Where(i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(IQueryable <>)).ToList();
if (queryables.Count > 1)
{
throw new Exception("Types inheriting IQueryable<T> more than once are not supported.");
}
if (queryables.Count == 1)
{
var entityType = queryables[0].GetGenericArguments()[0];
var method = typeof(SchemaExtensions).GetMethod("AddQueryToListSimple", BindingFlags.Static | BindingFlags.NonPublic);
var genMethod = method.MakeGenericMethod(typeof(TContext), entityType);
var getter = Expression.Lambda(typeof(Func <,>).MakeGenericType(typeof(TContext), queryables[0]), queryableGetter.Body, queryableGetter.Parameters[0]);
genMethod.Invoke(null, new object[] { context, name, getter });
}
else
{
var info = GetQueryInfo(queryableGetter);
if (info.ResolutionType != ResolutionType.Unmodified)
{
context.AddQueryInternal(name, GetFinalQueryFunc <TContext, object, IQueryable <TEntity> >(info.BaseQuery), info.ResolutionType);
}
else
{
context.AddUnmodifiedQueryInternal(name, GetFinalQueryFunc <TContext, object, TEntity>(info.OriginalQuery));
}
}
}