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Many to Many with additional field in middle table

Arkady

24 Jun, 2010 03:31 PM via web

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Good day,

i would like to use FH in my project. Here is the question came up in the middle of the way:
Lets say i have two tables related as many to many:
ProcessTable:
Id
Name
Description

PluginTable:
Id
Name
Description

Here is the middle table created by FH:

ProcessToPlugin:
Process_Id
Plugin_Id

Question - i would need to have one more field in ProcessToPlugin table, so it would like:
ProcessToPlugin:
Process_Id
Plugin_Id
PluginSettings_Id

PluginSettings_Id is some digit value used program.

Which settings in FH i may do to have this structure? Is it possible?

1. Support Staff 2 Posted by Paul Batum on 28 Jun, 2010 11:22 AM

   

   Once your joining table for a many-to-many has an additional field on it,
   its not really a many to many anymore. The common way that people solve it
   is like this:

   public class Process
   {
     public IList<ProcessPlugin> Plugins { get; set; }
   }

   public class ProcessPlugin
   {
     public Process Process { get; set; }
     public Plugin Plugin { get; set; }
     public Settings Settings { get; set; }
   }

   public class Plugin
   {
     public IList<ProcessPlugin> Processes { get; set; }
   }

   public ProcessMap()
   {
     HasMany(x => x.Plugins);
   }

   public ProcessPluginMap()
   {
     References(x => x.Process);
     References(x => x.Plugin);
     References(x => x.Setting);
   }

   public PluginMap()
   {
     HasMany(x => x.Processes);
   }

   Obviously this works but its not perfect. You can also make those lists
   private and then expose them as a list of Plugins (instead of a list of
   ProcessPlugins).

   The other alternative that might work in your case is a ternary mapping. It
   uses a dictionary, something like this:

   public class Process
   {
     public IDictionary<Settings, Plugin> Plugins { get; set; }
   }

   But this is a bit different and I'm not sure if it can work for your
   scenario.

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