Question

我想知道是否有人告诉我为什么Queries上ObservableCollection列表的过滤在我的下面的代码中不起作用？ Queries.List.Where(x => x.Name.Equals(value))总是有整个列表..没有过滤。我的lambda表达式有问题吗？

视图模型：

namespace DataRetrieval.ViewModel
{
    public class QueriesViewModel:BindableBase
    {
        public QueriesViewModel()
        {
            Queries = new Queries();

                for (int i = 0; i < 5; ++i)
                {

                    var query = new Query { Name = "Query "+i.ToString() };

                    Queries.List.Add(query);
                }

        }

        private Queries _queries;
        public Queries Queries
        {
            get { return _queries; }
            set { SetProperty(ref _queries, value); }
        }

        private string _filter1;
        public string Filter1
        {
            get { return _filter1; }
            set { 
                SetProperty(ref _filter1, value);
                filterlist(Filter1);
            }
        }
        private void filterlist(string value)
        {
            Queries.List.Where(x => x.Name.Equals(value));
        }

    }
}

型号：

  public class Queries : BindableBase
    {

        private ObservableCollection<Query> _list;
        public ObservableCollection<Query> List
        {
            get { return _list ?? (_list = new ObservableCollection<Query>()); }
            set { SetProperty(ref _list, value); }
        }

    }
    public class Query:BindableBase
    {
        private string _name;
        public string Name
        {
            get { return _name; }
            set { 
                SetProperty(ref _name, value); 
            }
        }
        private string _type;
        public string Type
        {
            get { return _type; }
            set { SetProperty(ref _type, value); }
        }
        private QDatatables _tables;
        public QDatatables Tables
        {
            get { return _tables; }
            set { SetProperty(ref _tables, value); }
        }

    }

Answer 1

Queries.List.Where()返回一个新值，因此要么将其设置回Queries.List（如@Valera在评论中所述），要么像这样返回：

Queries.List = Queries.List.Where(x => x.Name.Equals(value));

或

return Queries.List.Where(x => x.Name.Equals(value));

修改：返回无法正常工作，因为它位于void函数中，您必须更改它，或者使用@ Valera的方法。

Answer 2

int num = 3;
int max = 100;

for(int i = num; i <= max; i += num)
 System.out.println(i);//3 6 9...

使用lambda表达式过滤ObservableCollection列表

2 个答案: