小编Bil*_*ill的帖子

我正在使用实体框架并动态地使用导航属性构建查询.

对于我的大多数用例,以下工作正常:

private static MethodCallExpression GetNavigationPropertyExpression<T>(string propertyName, int test,
        ParameterExpression parameter, string subParameter)
    {
        var navigationPropertyCollection = Expression.Property(parameter, propertyName);

        var childType = navigationPropertyCollection.Type.GetGenericArguments()[0];

        var anyMethod = typeof(Enumerable).GetMethods().Single(m => m.Name == "Any" && m.GetParameters().Length == 2).MakeGenericMethod(childType);

        var aclAttribute = GetAclAttribute(typeof(T), propertyName);
        var childProperty = aclAttribute.ChildProperty;

        var propertyCollectionGenericArg = childType;
        var serviceLocationsParam = Expression.Parameter(propertyCollectionGenericArg, subParameter);

        var left = Expression.Property(serviceLocationsParam, childProperty);
        var right = Expression.Constant(test, typeof(int));

        var isEqual = Expression.Equal(left, right);
        var subLambda = Expression.Lambda(isEqual, serviceLocationsParam);

        var resultExpression = Expression.Call(anyMethod, navigationPropertyCollection, subLambda);

        return …