Relationship scenario (Many to Many Relationship)
- Trainer can train on multiple Courses
- Eg- T1 Trainer trains on C1 and C2 Courses
- Course can be handled by multiple Trainers
- Eg- 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 manger 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
CodeProject
Relationships scenario( One To Many Relationship)
https://www.youtube.com/watch?v=9qyRIW0FTZ8
- Course can have multiple Students
- Student can select only one course
- Open the student table and add the Navigational property for course table
- Configure the Foreign key as CourseId to the Student Table
- Execute the command "ADD-Migration" in the package manager console after the modification in model file for configuring Foreign Key in Student table
- Script gets generated
- Once the script got generated, update the database.
- Once after executing the "Update-database" command in package manger console, script present in the "up method " of the configuration file will be executed in the SQL Server and Foreign Key will be created
- Add the required changes in the create action method in the Student Controller
- Create a dropdownlist in the viewpage for selecting the course for particular student in the "create.cshtml" view page
- Modify the Edit Action method and Edit.cshtml viewpage
- Run the application and test it.
- DropdownList for selecting the course will be present and
- 1 to Many Relationship and ForeignKey is configured and established
CodeProject
