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如何使用 LINQ 对集合及其子集合进行排序？

发布于 2024-10-07 11:53:59 字数 390 浏览 1 评论 0原文

我有一组员工，每个员工都有一组职责。我想输出按姓名排序的员工列表，并输出按职务排序的他们的职责。

因此，它应该这样输出：

Jane Jones

职责：

职责 A

职责 B

迈克史密斯

职责：

职责 A

职责 C

要获取我使用的初始集合：

var employees = _context.Employees.OrderBy(e => e.Name);

但我似乎也不知道如何订购职责子集合。

我正在使用 MVC，并且我的视图接收强类型的 Employee 集合，因此我不想构建并返回匿名类型。

原文

I have a collection of Employees, and each employee has a collection of Responsibilities. I would like to output a list of the employees sorted by Name and output their Responsibilities, sorted by Title.

So, it should be outputted like this:

Jane Jones

Responsibilities:

Responsibility A

Responsibility B

Mike Smith

Responsibilities:

Responsibility A

Responsibility C

To get the initial collection I use:

var employees = _context.Employees.OrderBy(e => e.Name);

but I can't seem to figure out how to order the Responsibilities subcollection as well.

I'm using MVC and my View receives a strongly typed Employee collection so I don't want to build and return an anonymous type.

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过期情话 2024-10-14 11:53:59

你可以这样做：

var employees = _context.Employees.OrderBy(e => e.Name);
employees.ToList().ForEach(e => e.Responsibilities = e.Responsibilities.OrderBy(r => r.Name));

You could do something like:

var employees = _context.Employees.OrderBy(e => e.Name);
employees.ToList().ForEach(e => e.Responsibilities = e.Responsibilities.OrderBy(r => r.Name));

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冰之心 2024-10-14 11:53:59

第一种方法：（仅适用于职责定义为 IList 的 LINQ to 对象）

您可以复制到新的员工集合中，但这意味着您需要重新复制每个字段都包含在新员工中，如下所示：

var employees = from e in _context.Employees
                orderby e.Name
                select new Employee
                {
                    Name = e.Name,
                    ...re-assign other properties...
                    Responsibilities = e.Responsibilities.OrderBy(r => r.Name).ToList()
                };

第二种方法：

使用数据加载选项。基本上，您创建一个 DataLoadOptions 对象，它指定如何对特定关系进行排序，因此在您的情况下：

var options = new DataLoadOptions();
options.AssociateWith<Employees>(e => e.Responsibilities.OrderBy(r => r.Name));
_context.LoadOptions = options;

var employees = _context.Employees.OrderBy(e => e.Name);

将自动对职责进行排序。

1st approach: (is only suitable for LINQ to Objects with Responsibilities defined as IList)

You could copy into a new collection of Employees but this means that you need to re-copy each field into new employee, something like this:

var employees = from e in _context.Employees
                orderby e.Name
                select new Employee
                {
                    Name = e.Name,
                    ...re-assign other properties...
                    Responsibilities = e.Responsibilities.OrderBy(r => r.Name).ToList()
                };

2nd approach:

Using the DataLoadOptions. Basically, you create a DataLoadOptions object which specifies how to order a particular relationship, so in your case:

var options = new DataLoadOptions();
options.AssociateWith<Employees>(e => e.Responsibilities.OrderBy(r => r.Name));
_context.LoadOptions = options;

var employees = _context.Employees.OrderBy(e => e.Name);

The Responsibilities will be ordered automatically.

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