Configure Many-To-Many Relationship and ListBox Control in MVC and Entity Framework

Relationship Scenario (Many to Many Relationship)

Video: https://www.youtube.com/watch?v=nzmk1hrYYtQ

Relationship scenario (Many to Many Relationship)

• Trainer can train on multiple Courses
• E.g.- T1 Trainer trains on C1 and C2 Courses

• Course can be handled by multiple Trainers
• E.g.- C3 Course is handled by T3, T4 and T5trainers

• Many to Many Relationship requires a new table (TrainsOnCourse) for storing the collections that are selected in the list box
• Create a new Model Trainer

  

• Execute the command "Add-Migration" in package manager console and update the database for adding the trainer table in the SQL Server database

  

• Build the solution and create a new model for "TrainsOnCourse" for storing the collections selected in the list box.

  

• Add a DBSet entity property for the TrainsOnCourse in the DBContext class.

  

• Modify the Trainer model for adding navigational property and for saving the collection items selected in the listbox.

  

• Build the solution and execute the "Add-Migration" command in the package manager console for adding the new table "TrainsOnCourse".
• Update the database for running the migration file in the SQL Server by executing the "update-database" command in package manager console.

  

• Open the SQL Server and new table "TrainsOnCourse" table should be created with 2 foreign keys.

  

• Add a new Controller "Trainer".
• Select the "Tranier.cs" model and "DNSCContext".

  

• Modify the Create Action method to add multiselect list values to be populated from the Course table from the database.

  

• Add a ListBoxControl in "Create.cshtml" view page in Trainer folder.

  

• Run the application and goto "Trainer/Create" Actionmethod by entering in the url.
• We should be able to see the ListBox with set of values

  

• Save the collection list items to the database.
• Modify the HTTPPost create action method to save the selected items.

  

• Modify the Edit Action method in the Trainer controller for handling Listbox control.

  

• Open the "Edit.cshtml" view page of trainer and add the ListBox control.

  

• Open the HttpPost Edit Action method of the Trainer controller and perform the required operations.

  

• Test the application with listbox values selected with create and edit operations.