Question

I have been trying to implement a search page for the admin of my system. Long story short, there a 3 paramaters as criterias. 1. users, 2.projects, 3. customers. The admin can make any combination of those three criterias. for example “I would like to see all users which are assigned to this projects and also all the customers” or “I want to see this customer and this project but all the users” and so on. How do you implement such filtering? I am using asp.net 4.0 and linq just in case.

Here is the function content and it is all. I have made it by if conditions but it is not at all healthy.

public static List<Data.CurrentActivity> GetUsersActivitySearch(string employeeId, string projectId, string customerId, DateTime startDate, DateTime endDate)
        {
            DataClassesDataContext dc = new DataClassesDataContext(General.ConnectionString);

            if(projectId=="" && customerId!="")
              return  dc.CurrentActivities.Where(t => t.User.RecId.ToString() == employeeId && t.Customer.RecId.ToString() == customerId && t.ActivityDate >= startDate && t.ActivityDate <= endDate).ToList();
            else if (projectId != "" && customerId == "")
                return dc.CurrentActivities.Where(t => t.User.RecId.ToString() == employeeId && t.Project.RecId.ToString() == projectId && t.ActivityDate >= startDate && t.ActivityDate <= endDate).ToList();
            else if (projectId != "" && customerId != "")
                return dc.CurrentActivities.Where(t=>t.User.RecId.ToString()==employeeId && t.Customer.RecId.ToString()==customerId && t.Project.RecId.ToString()==projectId && t.ActivityDate>=startDate && t.ActivityDate<=endDate).ToList();
            return dc.CurrentActivities.Where(t => t.User.RecId.ToString() == employeeId && t.ActivityDate >= startDate && t.ActivityDate <= endDate).ToList();
        }

Answer 1

Now that I see your code, i have a easy solution. You can actually compound where clause on the IQueryable interface because of the lazy execution:

        DataClassesDataContext dc = new DataClassesDataContext(General.ConnectionString);
        var result = dc.CurrentActivies.Where(t.ActivityDate >= startDate && t.ActivityDate <= endDate);

        if(userId.Length > 0)
            result = result.Where(t => t.User.RecId.ToString() == employeeId);

        if (projectId.Length > 0)
            result = result.Where(t => t.Project.RecId.ToString() == projectId);

        if (customerId.Length > 0)
            result = result.Where(t=>t.Customer.RecId.ToString()==customerId);

        return result.ToList();

---

If you had a generalized object that could represent enough information to display your results. Then you could do something like this:

public IList<SearchResults> Search(string user, string customer, string project)
{
    return (from user in context.Users
        where SqlMethods.Like(user.Name, user) && user.Length > 0
        select new SearchResult
        {
            ... properties you care about
        })
        .Concat(from project in context.Projects
             where SqlMethods.Like(project, project.Name) && project.Length > 0
             select new SearchResult
             {
                 ///
             })
        .Concat(from customer in context.Customers
             where SqlMethods.Like(customer, customer.Name) && customer.Length > 0
             select new SearchResult
             {
                 ///
             })
        .ToList();
}