Question

有：

初始化anonymouse集合（我会将其作为json发送）

var myCollection = new[]
{
    new
    {
        Code = 0,
        Name = "",
        OtherAttribute = ""
    }

}.ToList();

myCollection.Clear();

获取数据。

myCollection = (from iPeople in ctx.Person
                join iAnotherTable in ctx.OtherTable
                on iPeople.Fk equals iAnotherTable.FK
                ...
                order by iPeople.Name ascending
                select new
                {
                    Code = iPeople.Code,
                    Name = iPeople.Name,
                    OtherAttribute = iAnotherTable.OtherAtribute
                }).ToList();

我想添加一个Identity列，我需要订购该集合，并从1计数到collection.count。用于将此计数器绑定到表（jtable）中的列。

var myCollection = new[]
{
    new
    {
        Identity = 0,
        Code = 0,
        Name = "",
        OtherAttribute = ""
    }

}.ToList();

myCollection = (from iPeople in ctx.Person
                join iAnotherTable in ctx.OtherTable
                on iPeople.Fk equals iAnotherTable.FK
                ...
                order by iPeople.Name ascending
                select new
                {
                    Identity = Enum.Range(1 to n)//Here I don´t know how to do; in pl/sql would be rownum, but in Linq to SQL how?
                    Code = iPeople.Code,
                    Name = iPeople.Name,
                    OtherAttribute = iAnotherTable.OtherAtribute
                }).ToList();

Answer 1

如果您使用linq实体或linq to sql，请从服务器和ToList（）获取数据。很可能这个答案不会转换为sql，但我还没有尝试过。

List<string> myCollection = new List<string>();
myCollection.Add("hello");
myCollection.Add("world");
var result = myCollection.Select((s, i) => new { Identity = i, Value = s }).ToList();

Answer 2

正如西蒙在评论中所说，这可能如下所示：

int counter = 0; //or 1.
myCollection = (from iPeople in ctx.Person
            join iAnotherTable in ctx.OtherTable
            on iPeople.Fk equals iAnotherTable.FK
            ...
            order by iPeople.Name ascending
            select new
            {
                Identity = counter++,
                Code = iPeople.Code,
                Name = iPeople.Name,
                OtherAttribute = iAnotherTable.OtherAtribute
            }).ToList();

执行这种代码有什么问题吗？

Answer 3

正如西蒙在评论中所说的那样，考虑以下几点，尽管是做作的例子：

int i = 0;
var collection = Enumerable.Range(0, 10).Select(x => new { Id = ++i });

Answer 4

帮助我实现相同目标的一个解决方案：像这样创建一个单独的函数：

        private int getMaterialOrder(ref int order)
        {
            return order++;
        }

然后在您的 linq 查询中调用它，例如：

...
 select new MaterialItem() { Order=getMaterialOrder(ref order), 
...

如何使用Linq向订单添加订单（autoIncrement）属性？

4 个答案: