Linq, Expressions, NHibernate and Like comparison

Question

I am trying to do a like comparison based on an outside parameter (passed by a search form) that determines type of comparison (\"%string\" or \"string%\"

Answer 1

Sounds like you should be wanting to use:

query = query.Where(
Entity.StringProperty.Contains("SearchString")
)

This should map to:

WHERE StringProperty LIKE '%SearchString%'

This should also work for more advanced search masks such as "Mr? Sm%th", but I haven't had to test any search strings like that myself yet.

---

UPDATE: Based on OPs edit

It sounds like what you are asking for is something like the following:

   public enum SelectedComparsionType
    {
        StartsWith,
        EndsWith,
        Contains
    }

public static bool Like(this string searchString, string searchPattern, SelectedComparsionType searchType)
{
    switch (searchType)
    {
        case SelectedComparsionType.StartsWith:
            return searchString.StartsWith(searchPattern);
        case SelectedComparsionType.EndsWith:
            return searchString.EndsWith(searchPattern);
        case SelectedComparsionType.Contains:
        default:
            return searchString.Contains(searchPattern);
    }
}

This would allow you to write code as you require, i.e:

query = query.Where(
Entity.StringProperty.Like("SearchString", SelectedComparsionType.StartsWith)
)

However, personally, I would replace any use of SelectedComparsionType, with a direct call to the required string function. I.e

query = query.Where(
Entity.StringProperty.StartsWith("SearchString")
)

As this will still map to a SQL 'LIKE' query.