LINQ查询到ObservableCollection吗? [英] LINQ query into ObservableCollection?

问题描述

将LINQ结果转换为ObservableCollection

乔恩·斯基特(Jon Skeet)在这个问题上给出了很好的答案，但我仍然无法自己做.

Jon Skeet give a great answer in the question ,but I still cannot make my own.

对类的新手，与他们一起学习阶段.

Still new to classes, so I am still in the learning phases with them.

我制作了LINQ to SQL类，显然有很多自动生成的代码.这是添加该类时生成的该类的片段，与该问题有关.显然，这已链接到名为Staff_Time_TBL的数据库表.

I have made a LINQ to SQL class and obviously there is a lot of auto generated code. This is the a snippet of the class generated when adding the class, that is relevant to this question. This is obviously linked to the DataBase Table named Staff_Time_TBL.

public partial class Staff_Time_TBL : INotifyPropertyChanging, INotifyPropertyChanged
    {

        private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);

        private long _ID;

        private System.Nullable<System.DateTime> _Date_Data;
    }

我有一个工作类，可以将所需的数据输入到Datagrid中， 它从两个日期之间以及具有唯一员工编号的工作人员中提取数据.这可以正常工作，但是当直接将数据更新到数据库时，界面中的数据不会更新，

I have a working class that I made that gets the data I need into the Datagrid, It pulls data from between two dates and from a Staff Member with a unique staff number. This works fine, but when updating data dirrectly to the database, the data in the interface is not updated ,see this question.

internal class DatabaseQueries
    {
        public static IEnumerable<Staff_Time_TBL> MainTable(DatabaseDataContext database, DateTime fromDate, DateTime toDate, int employeeNumber)
        {
            return database.Staff_Time_TBLs.Where(staff =>
                staff.Date_Data > fromDate &&
                staff.Date_Data < toDate &&
                staff.Staff_No == employeeNumber);
        }

此答案中的这段代码是可以理解的，但是我不知道foo是什么?

This code in this answer is understandable, but I have no idea what foo would need to be?

var linqResults = foos.Where(f => f.Name == "Widget");

var observable = new ObservableCollection<Foo>(linqResults);

如何制作一个Observablecollection类来容纳LINQ查询?

How can I make an Observablecollection Class to hold the LINQ query?

这是我尝试做的事情，但在查询时出现了编译错误.

This is what I tried to do something, but gives me a compile error at the query.

无法隐式转换类型 'System.Collections.Generic.List'到 'System.Collections.ObjectModel.ObservableCollection'

Cannot implicitly convert type 'System.Collections.Generic.List' to 'System.Collections.ObjectModel.ObservableCollection'

public ObservableCollection<Staff_Time_TBL> observerableInfoData { get; set; }

        public MainWindow()
        {  
            DataContext = this; // required for C# binding
            InitializeComponent();            

                            observerableInfoData = new ObservableCollection<Staff_Time_TBL>();
                observerableInfoData = sql.Staff_Time_TBLs.Where(staff => staff.Staff_No == SelectedEmployee.Key &&
                                               staff.Date_Data == filterFrom &&
                                               staff.Date_Data == filterTo).Select(staff => staff.Info_Data).ToList();

推荐答案

基本上，您需要将实际查询的IEnumerable<Staff_Time_TBL>结果传递给数据库以初始化ObservableCollection<Staff_Time_TBL>:

Basically, you need to pass IEnumerable<Staff_Time_TBL> result of the actual query to the database to initialize the ObservableCollection<Staff_Time_TBL> :

var linqResults = sql.Staff_Time_TBLs
                     .Where(staff => staff.Staff_No == SelectedEmployee.Key &&
                                     staff.Date_Data == filterFrom &&
                                     staff.Date_Data == filterTo);

var observable = new ObservableCollection<Staff_Time_TBL>(linqResults);

这篇关于LINQ查询到ObservableCollection吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！