C # (NOP) drop-down list (with foreign keys)

The first case. The view view is loaded with values, and the following steps are implemented

1. Create public list<selectlistitem> XXX (name) {get; set;} in the interface model of the operation

2. Instantiate this.courses = new list<selectlistitem> () in the constructor in the model, and a collection of instances

Note: 1 and 2 are done in the same model.

3. In the controller:

(1) All data is queried from the database (implemented via the interface)

(2) using a foreach traversal to instantiate a variable (type SelectListItem)

Examples are:

var courses = _courseservice.getallcourses (); // querying data            from data foreach (var in courses)            {                new selectlistitem (); // instantiate a variable                Li. Text = course. Coursename;                 = course. Id.tostring ();                Model. Courses.add (li);            }

4. In the interface

  @Html. dropdownlistfor (x = X.courseid (name)// ID to query name

In the second case, the view view is loaded with no value and the following steps are implemented:

There is a difference between the first and only the controller:

Example:

 varModel =NewSclistmodel ();//Intermediate Modelvarcourses=_courseservice.getallcourses (); SelectListItem Li=NewSelectListItem (); Li. Text=""; Li. Value=""; Model.            Scnames.add (LI); foreach(varIteminchcourses) {Li=NewSelectListItem (); Li. Text=item.                Coursename; Li. Value=item.                Id.tostring (); Model. Scnames.add (LI);

4. Interface

<tr>        Class="admintitle">         <span> course Name: </span >        </td>               class="admindata">              = model. CourseID, Model.scnames)//id for        values </td>    </tr>

C # (NOP) drop-down list (with foreign keys)