C# 通用列表属性设置/添加行为

发布于 2024-12-11 05:47:47 字数 744 浏览 1 评论 0原文

我想在 ASP.NET 用户控件的视图状态中存储通用列表，因此我有以下代码：

    protected List<MoodleCourse> MoodleCoursesCreated
    {
        get
        {
            if (ViewState["MoodleCoursesCreated"] == null)
            {
                return new List<MoodleCourse>();
            }
            else
            {
                return (List<MoodleCourse>)ViewState["MoodleCoursesCreated"];
            }
        }
        set
        {
            ViewState["MoodleCoursesCreated"] = value;
        }
    }

因此，要将项目添加到列表中，我调用 MoodleCoursesCreated.Add(new MoodleCourse);

然而，似乎我必须执行 MoodleCourseCreated = MoodleCourseCreated 来激活设置器，以便列表实际上存储在视图状态中。我怀疑有一种更优雅的方法来实现这一点，有人有什么建议吗？干杯

原文

I want to store a generic list in the viewstate in an ASP.NET user control, so I have the following code:

    protected List<MoodleCourse> MoodleCoursesCreated
    {
        get
        {
            if (ViewState["MoodleCoursesCreated"] == null)
            {
                return new List<MoodleCourse>();
            }
            else
            {
                return (List<MoodleCourse>)ViewState["MoodleCoursesCreated"];
            }
        }
        set
        {
            ViewState["MoodleCoursesCreated"] = value;
        }
    }

So to add an item to the list, I call MoodleCoursesCreated.Add(new MoodleCourse);

However it seems then I must do MoodleCourseCreated = MoodleCourseCreated to activate the setter so the list actually gets stored in the viewstate. I suspect there is a more elegant way to achieve this, does anyone have any suggestions? Cheers

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小嗲 2024-12-18 05:47:47

调用 .Add() 你永远不会触发设置器。我想，你根本不需要二传手。相反，重写 Add() 方法或创建自己的 AddMoodleCourse(MoodleCourse mudleCourse)：

protected void AddMoodleCourse(MoodleCourse moodleCourse)
{
    var courses = ViewState["MoodleCoursesCreated"] as List<MoodleCourse>;
    if (courses == null)
    {
         courses = new List<MoodleCourse>();
         ViewState["MoodleCoursesCreated"] = courses;
    }
    courses.Add(moodleCourse);
}

然后调用 MoodleCoursesCreated.AddMoodleCourse(new MoodleCourse);

Calling .Add() you never trigger the setter. I guess, you don't need setter at all. Instead, override Add() method or create your own AddMoodleCourse(MoodleCourse moodleCourse):

protected void AddMoodleCourse(MoodleCourse moodleCourse)
{
    var courses = ViewState["MoodleCoursesCreated"] as List<MoodleCourse>;
    if (courses == null)
    {
         courses = new List<MoodleCourse>();
         ViewState["MoodleCoursesCreated"] = courses;
    }
    courses.Add(moodleCourse);
}

and now call MoodleCoursesCreated.AddMoodleCourse(new MoodleCourse);

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那小子欠揍 2024-12-18 05:47:47

protected List<MoodleCourse> MoodleCoursesCreated
{
    get
    {
        if (ViewState["MoodleCoursesCreated"] == null)
        {
            ViewState["MoodleCoursesCreated"] = new List<MoodleCourse>();
        }
        return (List<MoodleCourse>)ViewState["MoodleCoursesCreated"];
    }
    set
    {
        ViewState["MoodleCoursesCreated"] = value;
    }
}

protected List<MoodleCourse> MoodleCoursesCreated
{
    get
    {
        if (ViewState["MoodleCoursesCreated"] == null)
        {
            ViewState["MoodleCoursesCreated"] = new List<MoodleCourse>();
        }
        return (List<MoodleCourse>)ViewState["MoodleCoursesCreated"];
    }
    set
    {
        ViewState["MoodleCoursesCreated"] = value;
    }
}

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勿忘初心 2024-12-18 05:47:47

如果您希望某个属性在 getter 中产生副作用，请不要使用该属性。相反，只需使用这样的方法：

protected List<MoodleCourse> GetMoodleCourses()
{
    List<MoodleCourse> list = (List<MoodleCourse>)ViewState["MoodleCoursesCreated"];
    if (list == null)
    {
        list = new List<MoodleCourse>();
        ViewState["MoodleCoursesCreated"] = list;
    }
    return list;
}

Don't use a property if you want it to have side-effects in the getter. Instead just use a method like this:

protected List<MoodleCourse> GetMoodleCourses()
{
    List<MoodleCourse> list = (List<MoodleCourse>)ViewState["MoodleCoursesCreated"];
    if (list == null)
    {
        list = new List<MoodleCourse>();
        ViewState["MoodleCoursesCreated"] = list;
    }
    return list;
}

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木有鱼丸 2024-12-18 05:47:47

你应该在 getter 中保留相同的引用：

protected List<MoodleCourse> MoodleCoursesCreated
{
    get
    {
        if (ViewState["MoodleCoursesCreated"] == null)
            ViewState["MoodleCoursesCreated"] = new List<MoodleCourse>();
        return ViewState["MoodleCoursesCreated"] as List<MoodleCourse>;
    }
    set
    {
        ViewState["MoodleCoursesCreated"] = value;
    }
}

you should hold the same reference in the getter:

protected List<MoodleCourse> MoodleCoursesCreated
{
    get
    {
        if (ViewState["MoodleCoursesCreated"] == null)
            ViewState["MoodleCoursesCreated"] = new List<MoodleCourse>();
        return ViewState["MoodleCoursesCreated"] as List<MoodleCourse>;
    }
    set
    {
        ViewState["MoodleCoursesCreated"] = value;
    }
}

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