Dynamically Build EF Query

Have a look at this code:

public static class CustomQueryBuilder
{
    //todo: add more operations
    public enum Operator
    {
        Equal = 0,
        GreaterThan = 1,
        LesserThan = 2
    }

    public static IQueryable<T> Where<T>(this IQueryable<T> query, string property, Operator operation, object value)
    {
        //it's an item which property we are referring to
        ParameterExpression parameter = Expression.Parameter(typeof(T));
        //this stands for "item.property"
        Expression prop = Expression.Property(parameter, property);

        //wrapping our value to use it in lambda
        ConstantExpression constant = Expression.Constant(value);

        Expression expression;
        //creating the operation
        //todo: add more cases
        switch (operation)
        {
            case Operator.Equal:
                expression = Expression.Equal(prop, constant);
                break;
            case Operator.GreaterThan:
                expression = Expression.GreaterThan(prop, constant);
                break;
            case Operator.LesserThan:
                expression = Expression.LessThan(prop, constant);
                break;
            default:
                throw new ArgumentException("Invalid operation specified");
        }

        //create lambda ready to use in queries
        var lambda = Expression.Lambda<Func<T, bool>>(expression, parameter);

        return query.Where(lambda);
    }
}

Usage

var users = context
    .Users
    .Where("Name", CustomQueryBuilder.Operator.Equal, "User")
    .ToList();

Which is equal to

var users = context
    .Users
    .Where(u => u.Name == "User")
    .ToList();