LINQ从另一个更新一个列表 [英] LINQ Update one list from another

问题描述

我正在尝试找到一种优雅的方法来更新ConcurrentDictionary中的值.我在下面创建了一个我要实现的目标的快速示例:

I'm trying to find an elegant way of updating values in a ConcurrentDictionary. I've created a quick example of what I'm trying to achieve below:

ConcurrentDictionary<int, MyDataClass> dataLookup = new ConcurrentDictionary<int, MyDataClass>();

// Initialise the example dataLookup with some dummy data
new List<MyDataClass>
{
    new MyDataClass { Id = 1, ValueProperty = 0 },
    new MyDataClass { Id = 2, ValueProperty = 0 },
    new MyDataClass { Id = 3, ValueProperty = 0 },
    new MyDataClass { Id = 4, ValueProperty = 0 },
    new MyDataClass { Id = 5, ValueProperty = 0 }               
}.ForEach(myClass => dataLookup.TryAdd (myClass.Id, myClass));

// incoming results that need to be fed into the above dataLookup 
List<MyDataClass> newDataReceived = new List<MyDataClass>
{
    new MyDataClass { Id = 1, ValueProperty = 111 },
    new MyDataClass { Id = 3, ValueProperty = 222 },
    new MyDataClass { Id = 5, ValueProperty = 333 }
};

因此，在上面的示例中，我想在ID为1、3&的dataLookup ConcurrentDictionary中设置ValueProperty.分别为5至111、222和333.我可以将newDataReceived对象更改为我想要的任何对象，但是我对dataLookup作为ConcurrentDictionary感到很困惑.

So in the above example I want to set the ValueProperty in the dataLookup ConcurrentDictionary with the Id of 1, 3 & 5 to 111, 222 and 333 respectively. I can change the newDataReceived object into anything I want but I'm pretty much stuck with the dataLookup as a ConcurrentDictionary.

目前，我正在遍历列表，但是正在寻找有关使用LINQ来提高此任务效率的一些建议.

At the moment I'm iterating through the list but I'm looking for some suggestions on using LINQ to make this task more efficient.

推荐答案

如果确实是即将到来的更新，则可以使用另一个ForEach:

If it's truly just updates that are coming in, you could just use another ForEach:

newDataReceived.ForEach(x => dataLookup[x.Id].ValueProperty = x.ValueProperty);

我个人只是用一个简单的foreach循环来表达这一点:

Personally I would just express this with a simple foreach loop though:

foreach(var update in newDataReceived)
    dataLookup[update.Id].ValueProperty = update.ValueProperty;

请注意，上述方法缺少对并发字典中是否确实包含该项的检查-如果不能保证(不是更新)，则必须添加此检查.

Note that above is missing a check whether the item is actually contained in the concurrent dictionary - if that is not guaranteed (it's not an update) you would have to add this check.

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