Question

以下代码在我的索引控制器操作中运行良好使用数据库数据填充下拉框。

我不想直接在我的控制器中使用它，因为我将使用它我页面上多个位置的下拉列表。

var db = new StoreManagerEntities();
        var query = db.Categories.Select(c => new
        {
            CategoryId = c.CategoryID,
            Categoryname = c.CategoryName,
            IsSelected = c.CategoryID.Equals(0)
        });

        var model = new SelectViewModel
        {
            List = query.ToList()
                        .Select(c => new SelectListItem
                        {
                            Value = c.CategoryId.ToString(),
                            Text = c.Categoryname,
                            Selected = c.IsSelected,
                        })
        };

        return View(model);

我希望能够将代码放在方法中并从我的控制器中调用此方法这是我想要方法的另一个类。

public class NorthwindDataContext
{

    StoreManagerEntities myDb = new StoreManagerEntities();

    //retrieve all category objects
    public List<Category> GetCategories()
    {
        return myDb.Categories.ToList();
    }

    //populate dropdownbox
        public void PopulateDropdown()
        {
              var query = db.Categories.Select(c => new
        {
            CategoryId = c.CategoryID,
            Categoryname = c.CategoryName,
            IsSelected = c.CategoryID.Equals(0)
        });

        var model = new SelectViewModel
        {
            List = query.ToList()
                        .Select(c => new SelectListItem
                        {
                            Value = c.CategoryId.ToString(),
                            Text = c.Categoryname,
                            Selected = c.IsSelected,
                        })
        };

        }


}

  Can you please show me how I can write the method here and have it 
  return the data I need back to the controller. It will be nice if you 
  can show me how to call this from the controller as well.

Answer 1

如何更改NorthwindDataContext类

public class NorthwindDataContext
    {
        StoreManagerEntities myDb = new StoreManagerEntities();    
        //retrieve all category objects
        public List<Category> GetCategories()
        {
            return myDb.Categories.ToList();
        }    
        //populate dropdownbox
        public SelectViewModel PopulateDropdown()
        {
            var query = db.Categories.Select(c => new
                {
                    CategoryId = c.CategoryID,
                    Categoryname = c.CategoryName,
                    IsSelected = c.CategoryID.Equals(0)
                });

            var model = new SelectViewModel
            {
                List = query.ToList()
                            .Select(c => new SelectListItem
                            {
                                Value = c.CategoryId.ToString(),
                                Text = c.Categoryname,
                                Selected = c.IsSelected,
                            })
            };
            return model;

        }    

    }

请注意PopulateDropdown()和return model;

的返回类型的更改

并在控制器中使用它，如：

var db = new NorthwindDataContext();
var model = db.PopulateDropdown();

return View(model);

Mvc：创建从类中填充下拉列表并从控制器调用的方法

1 个答案: