通过与某些字符串键启动一个切片的FormCollection [英] Slicing a FormCollection by keys that start with a certain string

问题描述

有没有拆分的FormCollection 到词典℃的不错的 linqy 的途径;字符串，字符串＆GT; 只包含那些具有一定的字符串开始键？

Is there a nice linqy way of splitting a FormCollection into a Dictionary<string,string> that contains only those keys that start with a certain string?

的（这个问题是基本相同，这 - >但对于C＃/的FormCollection而不是蟒蛇<一个href=\"http://stackoverflow.com/questions/4558983/slicing-a-dictionary-by-keys-that-start-with-a-certain-string\">Slicing与某些字符串开始一本词典的键）的

(This question is basically the same as this-> but for C#/FormCollection instead of python Slicing a dictionary by keys that start with a certain string)

这就是我想出了要解决这个问题：

Here's what I came up with to get around the problem:

public ActionResult Save(FormCollection formCollection) {
  var appSettings = new Dictionary<string, string>();
  var appKeys = formCollection.AllKeys.Where(k => k.StartsWith("AppSettings."));
  foreach (var key in appKeys)
  {
      appSettings[key] = formCollection[key];
  }
...

编辑：此code中的问题，是我必须多次做不同的StartsWith字符串，因此需要创建一个实用的方法做以上。
这将是很好，如果它可以像一行写着：

The problem with this code, is that I have to do it multiple times for different StartsWith strings, and will therefore need to create a 'utility' method to do the above. It would be nice if it could read in one line like:

formCollection.Where(k=>k.Key.StartsWith("AppSettings.");

<强>背景（解决问题没有必要）：的上下文是asp.net的MVC，并与字段的动态辞典的表单

Background (not necessary to solve the problem): The context is asp.net mvc, and of a form with a dynamic dictionary of fields.

这也是类似于这样的问题 - 返回的FormCollection项目与preFIX - 但不完全一样。

It's also similar to this question - Return FormCollection items with Prefix - but not quite the same.

和看了这个答案<一个href=\"http://stackoverflow.com/questions/2845304/how-to-build-c-object-from-a-formcollection-with-complex-keys\">How从复杂的按键一的FormCollection打造C＃对象 - 我开始怀疑我是否会更好，即使不使用表单提交，但发送JSON而不是

And having read this answer How to build C# object from a FormCollection with complex keys - I started to wonder whether I'd be better off not even using form post, but sending JSON instead.

推荐答案

如果你正在寻找采取现有的字典中好的方式，生产具有键+值的副本一个新的字典，为的一个子集钥匙，一些LINQ code将做到这一点很好：

If you're looking for a "nice" way of taking an existing dictionary, producing a new dictionary with copies of keys+values, for a subset of the keys, some LINQ code will do this nicely:

var appSettings = formCollection.AllKeys
    .Where(k => k.StartsWith("AppSettings."))
    .ToDictionary(k => k, k => formCollection[k]);

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