Question

IEnumerable<Dictionary<string, object>> ListOfDic = new List<Dictionary<string, object>>()
        {
            new Dictionary<string, object> {{"Name", "Stud 1"}, {"Id", 111}},
            new Dictionary<string, object> {{"Result", "Pass"}, {"Id", 111}},
            new Dictionary<string, object> {{"Name", "Stud 2"}, {"Id", 222}},
            new Dictionary<string, object> {{"Result", "Pass"}, {"Id", 222}},
            new Dictionary<string, object> {{"Name", "Stud 3"}, {"Id", 333}},
            new Dictionary<string, object> {{"Result", "Pass"}, {"Id", 333}},
            new Dictionary<string, object> {{"Name", "Stud 4"}, {"Id", 444}},
            new Dictionary<string, object> {{"Result", "Fail"}, {"Id", 444}},
            new Dictionary<string, object> {{"Name", "Stud 5"}, {"Id", 555}},
            new Dictionary<string, object> {{"Result", "Pass"}, {"Id", 555}},
            new Dictionary<string, object> {{"Name", "Stud 6"}, {"Id", 666}},
            new Dictionary<string, object> {{"Result", "Fail"}, {"Id", 666}},
            new Dictionary<string, object> {{"Name", "Stud 7"}, {"Id", 777}},
            new Dictionary<string, object> {{"Result", "Fail"}, {"Id", 777}},
            new Dictionary<string, object> {{"Name", "Stud 8"}, {"Id", 888}},
            new Dictionary<string, object> {{"Result", "Fail"}, {"Id", 888}},
            new Dictionary<string, object> {{"Name", "Stud 9"}, {"Id", 999}},
            new Dictionary<string, object> {{"Result", "Pass"}, {"Id", 999}}

        };

        List<int> StudentsToRemove = new List<int>() {555, 777, 888};

我想删除其id为555,777,888的词典中的所有元素。我尝试了以下解决方案，但它无效，在我的项目中， ListOfDic中有超过7000个元素。所以我认为最好将其转换为ToList()，以便RemoveAll()可以一次删除元素。如果有任何其他更好的解决方案，请告诉我。

//Tried Solution, Not Working !! :(
foreach (var stud in StudentsToRemove)
{
     ListOfDic.ToList().RemoveAll(a => a.ContainsValue(stud));
}

Answer 1

您说ToList无效，但可能 ;只是ToList创建了一个新集合，而RemoveAll不会影响您的原始集合。更糟糕的是，您正在循环的每次迭代中创建此列表。

因此，为了解决您的问题，您可以存储新的列表（并允许旧的列表进行垃圾收集）：

    List<Dictionary<string, object>> correctList = ListOfDic.ToList();
    foreach (var stud in StudentsToRemove)
    {
        correctList.RemoveAll(a => a.ContainsValue(stud));
    }

在您的方法中使用correctList代替ListOfDict。

Answer 2

你应该尝试这样的事情：

const { request, user } = param

您可以使用上面的代码将过滤后的集合分配给实际对象，而不是删除项目。这将检查字典中ListOfDic = ListOfDic.Where(x => x.Any(y => y.Key == "Id" && !StudentsToRemove.Contains((int)y.Value))).ToList();为key且Id

中未包含的任何项目

Answer 3

您对问题有答案，但我的解决方案是帮助您了解编码并使用最佳做法。 Dictionary类本身就是一个集合，因此将字典单例粘贴到列表中是错误的编码。我建议创建一个<Student>类，至少有两个属性Name和Result。然后使用字典<int,Student>，您可以为每个人创建一个条目。

class Student
{
    public string Name {get; set;}
    public string Result {get; set;}

    public Person(string name, string result)
    {
        this.Name =name;
        this.Result = result;
    }
}

Dictionary<int,Student> students = new Dictionary<int,Student>() {};
students[111] = new Student(){ "Stud 1", "Pass"};
students[222] = new Student(){ "Stud 2", "Pass"};
students[333] = new Student(){ "Stud 3", "Pass"};
students[444] = new Student(){ "Stud 4", "Fail"};
students[555] = new Student(){ "Stud 5", "Pass"};
students[666] = new Student(){ "Stud 6", "Fail"};
students[777] = new Student(){ "Stud 7", "Fail"};
students[888] = new Student(){ "Stud 8", "Fail"};
students[999] = new Student(){ "Stud 9", "Pass"};

然后，您可以从StudentsToRemove列表中删除所需的所有学生。制作动态（在运行时）列表以删除所有失败学生的示例：

foreach(int x in students.Where(x => x.Value.Result == "Fail").Select(x => x.Key).ToList() )
{
     students.Remove(x);
}

只是为了测试你的输出，看你有你想要的东西你可以使用它：

foreach(var x in students)
{
    Console.WriteLine("key:{0} Student name:{1} result:{2}",x.Key, x.Value.Name, x.Value.Result); 
}

C＃想要从IEnumerable <dictionary <string，object =“”>＆gt;中删除元素基于使用lambda表达式的条件？

3 个答案: