How to Implement Generic String Column Sorting with IQueryable's OrderBy?

Extend OrderBy to use generic parameters for string column sorting

How to sort IQueryable using string column names in generic extension method? Our existing method ApplySortFilter<T, TResult> has shortcomings because it requires specifying the type of OrderBy at runtime, which is not feasible.

Question:

public static IQueryable<TResult> ApplySortFilter<T, TResult>(this IQueryable<T> query, string columnName)
where T : EntityObject
{
    var param = Expression.Parameter(typeof(T), "o");
    var body = Expression.PropertyOrField(param, columnName);

    var sortExpression = Expression.Lambda(body, param);
    return query.OrderBy(sortExpression);
}

Solution:

To overcome this limitation, we need to infer the type of OrderBy from sortExpression. Here is a modified implementation:

public static IQueryable<T> OrderBy<T>(this IQueryable<T> source, string ordering, params object[] values)
{
    var type = typeof(T);
    var property = type.GetProperty(ordering);
    var parameter = Expression.Parameter(type, "p");
    var propertyAccess = Expression.MakeMemberAccess(parameter, property);
    var orderByExp = Expression.Lambda(propertyAccess, parameter);
    MethodCallExpression resultExp = Expression.Call(typeof(Queryable), "OrderBy", new Type[] { type, property.PropertyType }, source.Expression, Expression.Quote(orderByExp));
    return source.Provider.CreateQuery<T>(resultExp);
}

This modified method dynamically infers the type of the property being ordered and applies the OrderBy operation correctly.

Instructions on sorting in descending order:

For descending sorting, just replace "OrderBy" with "OrderByDescending" in MethodCallExpression.

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