Question

I have a very big problem solving this issue I have 2 tables

first table is : http://lh3.ggpht.com/_uMvfbnPHuko/SYPJQ1ZsBDI/AAAAAAAAAKs/eq49xquy3jM/s800/Untitled-2.jpg

which contains a modules (id and name)

second table is http://lh6.ggpht.com/_uMvfbnPHuko/SYPJQ4IXGwI/AAAAAAAAAK0/zmTIO6V-UEQ/s800/Untitled-3.jpg

which contains users ids and their preferred modules’ numbers

now lets move to the problem I want to generate a list of checkboxes

for example for the userid 1 which has the following modules ‘3,2 and 4’ the result will be

http://lh4.ggpht.com/_uMvfbnPHuko/SYPJQ_LJeVI/AAAAAAAAAK8/6RV8a1S8eCY/s800/Untitled-4.jpg

notice that ‘recommended for you’ checkbox is not checked because the user 1 does not have module id ‘1’

I spent a long time trying to solve this problem using c# and LINQ

see the result of my effort 🙂 (the following code does not work)

    var q = from m in db.modules             from um in db.usersModules.Where(um2 => um2.userId == myUserId).Single().modules.Trim().Split(',')             where um.Contains(m.moduleId.ToString())             select new             {                 moduleid = here i want the module id from modules table                 modulename = here i want the modulename from modules table                 ischecked = here i want 'true' or 'false' depending on if the user has this module or not              }; 

If LINQ is easy for you please try to solve this one? any questions?

Answer 1

Your query doesn’t works because LinqToSQL tries to translate everything to plain SQL.

If you cannot refactor your schema, and use an intermediate table since you clearly have a many-to-many relation ship, you can do something like this:

var userModules = db.userModules.SingleOrDefault(m => m.userId == myUserId).modules; // Get the modules of the user (a comma delimited string) var integerModules = modules.Split(',').Select(m => int.Parse(m)); // Convert the comma delimited string to IEnumerable<int>  var query = db.modules.Select(x => new {                 x.moduleId,                 x.moduleName,                 isChecked = integerModules.Contains(x.moduleId) }); // And finally do the query