Create expression tree for "like" on a decimal field

Question

I would like to create an expression tree for a query expression that looks something like this: employee => employee.Salary.StartsWith("28")

So that the sql could appear as: where (employee.salary like '28%')

The problem is that the property Salary of the employee object is a decimal and StartsWith is not a property of a decimal. How can i get around to do this.

My erroneous expression tree syntax is as follows:

var searchTextExp = Expression.Constant("28");
var parameterExp = Expression.Parameter(typeof(EmployeeEntity), "employee");
var propertyExp = Expression.Property(parameterExp, "Salary");
var startsWithExp = Expression.Call(propertyExp, "StartsWith", null, 
   searchTextExp);
Expression<Func<EmployeeEntity, bool>> searchExpr = 
   Expression.Lambda<Func<EmployeeEntity, bool>>
     (startsWithExp, new ParameterExpression[] { parameterExp });

Answer 1

I have managed to solve this using Function Mappings which is a feature of LLBLGEN Pro.

public class Functions
{
    public static bool Like(string field, string value)
    {
        return true;
    }

    public static bool Like(decimal field, string value)
    {
        return true;
    }
}

public class FunctionMappings : FunctionMappingStore
{
    public FunctionMappings()
        : base()
    {
        FunctionMapping mapping = new FunctionMapping(
            typeof(Functions), 
            "Like", 
            2, 
            "{0} LIKE {1}");

        this.Add(mapping);
    }
}

I then attached an instance of FunctionMappings to the LINQ Metadata:

metadata.Mappings = new FunctionMappings();

Then used the Function as follows:

employee => Functions.Like(employee.Salary,"28")