How can I cast an object to string and use it in a Linq query using Reflection-CodePudding

There's the problem I made an Extension method to IQueryable and I want to get property name and value to do a select on it the thing is that I am using Expression tree and try to search rows by the use of Contain() method which is needs a parameter of type string to do the job. my code is doing well while I do the search over string properties but I want this method to do the search on other types like int, decimal, datetime and even booleans so I need to get the property cast it to string and search for the matching values.

what I tried so far is:

        private static readonly MethodInfo _tostring = typeof(Object).GetMethod("ToString") ?? throw new Exception("Cannot create Method");

        public static IQueryable<T> Search<T>(this IQueryable<T> items, string propertyName, string filterValue)
        {
            MethodInfo _compare =
                (((Expression<Func<string, bool>>)(s => s.Contains("aa"))).Body as MethodCallExpression ?? throw new Exception("Cannot Create Method"))
                .Method;
            var property = typeof(T).GetProperty(propertyName) ?? throw new Exception("Couldn't Get the property");
            var row = Expression.Parameter(typeof(T), "row");

            
            Expression prop = Expression.Property(row, property);
            // now making sure if the type is string
            if (property.PropertyType != typeof(string))
            {
                //Here I want to cast it to string but the problem is exactly here anything I try feels like a dead end
                prop = Expression.Call(prop, _tostring);
            }

            var func =
                Expression.Lambda<Func<T, bool>>
                (
                    Expression.Call
                    (
                        prop,
                        _compare,
                        Expression.Constant(filterValue)
                    ),
                    row
                );

            return items.Where(func);
        }

CodePudding user response：

I tried and tested it with some dummy objects; it seems to work.

I refined my answer to use ToString

var prop = Expression.Property(row, property);

Expression expression = prop;

if (prop.Type != typeof(string))
{
   expression = Expression.Call(prop, "ToString", Type.EmptyTypes);
}

var func = Expression.Lambda<Func<T, bool>>
(
     Expression.Call
     (
       expression,
       _compare,
       Expression.Constant(filterValue)
     ),
     row
);

The above expression tree will be compiled to,

If the property type is not a string,

.Where(s => s.property.ToString().Contains("filter")))

If it's a string type,

.Where(s => s.property.Contains("filter")))