过滤前显示列表答案

【问题标题】：Display list before filtering过滤前显示列表
【发布时间】：2021-02-21 18:50:17
【问题描述】：

我有这个代码：

   private string employee = "";
    public string Employee
    {
        get => employee;
        set
        {
            employee = value;
            Employees = db.Employees.Where(x => x.Firstname.StartsWith(Employee) || x.Lastname.StartsWith(Employee)).ToList();
            RaisePropertyChangedEvent(nameof(Employee));
        }

    }
    private List<Employee> employees = new List<Employee>();
    public List<Employee> Employees
    {
        get => employees;
        set
        {
            employees = value;
            RaisePropertyChangedEvent(nameof(Employees));
        }
    }

到目前为止，这是有效的。如果用户键入 F，则会显示以 F 开头的每个员工。如果用户从文本框中删除 F，则会显示每个 Employee，但如果用户启动应用程序，则会显示一个空列表框。当用户启动应用程序时，每个员工都应该显示在文本框中

【问题讨论】：

将加载员工移动到专用方法，然后您可以控制何时加载他们。您可以将其移动到命令中，以便在更改搜索文本时调用它。或应用程序启动时。

标签： c# .net visual-studio mvvm

【解决方案1】：

使用私有变量所以替换：

        Employees = db.Employees.Where(x => x.Firstname.StartsWith(Employee) || x.Lastname.StartsWith(Employee)).ToList();

作者：

        Employees = db.Employees.Where(x => x.Firstname.StartsWith(employee) || x.Lastname.StartsWith(employee)).ToList();

【讨论】：

【解决方案2】：

替换

 private List<Employee> employees = new List<Employee>();

用这个：

 private List<Employee> employees = db.Employees.ToList();

【讨论】：

【解决方案3】：

在构建类时加载所有员工 -

public class MyCoolViewModel
{
    public MyCoolViewModel()
    {
        this.Employees = db.Employees.ToList();   // load all employees here
    }
    
    private string employee = "";
    public string Employee
    {
        get => employee;
        set
        {
            employee = value;
            Employees = db.Employees.Where(x => x.Firstname.StartsWith(Employee) || x.Lastname.StartsWith(Employee)).ToList();
            RaisePropertyChangedEvent(nameof(Employee));
        }

    }
    
    private List<Employee> employees;   // removed initialization from here
    public List<Employee> Employees
    {
        get => employees;
        set
        {
            employees = value;
            RaisePropertyChangedEvent(nameof(Employees));
        }
    }
}

【讨论】：