I have this function

public static async Task<Response> GetGeneralizedAsync<T>(int id, string key)
            where T : class
        {
            using var context = new Context();
            var prop = typeof(T).GetProperty(key);

            var list = await context.Set<T>().AsAsyncEnumerable().Where(x => prop.GetValue(x) == (object)id).ToListAsync();
            return new Response(StatusCodes.Status200OK, list);
        }

However it only works while using client side evaluation, and I'm worried about performance as this would be a very core function. Is it possible to do the same thing, but have it evaluate on the server, or at least improve the performance?

CodePudding user response：

The Queryable.Where() method expects a Expression<Func<TSource,bool>> expression, which is used to "evaluate" which entities should be returned when applied on the Set<T> instance. You can define your method that such an expression must be provided instead of the id and key values you have used. The method can look like this:

public static async Task<Response> GetGeneralizedAsync<T>(Expression<Func<T, bool>> predicate)
        where T : class
{
    using var context = new Context();

    var list = await context.Set<T>().Where(predicate)).ToListAsync();
    return new Response(StatusCodes.Status200OK, list);
}

Then you use it like this:

GetGeneralizedAsync<People>(p => p.Age == 38);