填充根据XML以前的组合框中选择一个组合框 [英] populate a combobox based on previous combobox selection in XML

问题描述

我是一个.NET初学者。我两个组合框即， cbProduct XML文件，并将其显示C $ C>和 cbBrandName

I am a .net beginner. I am reading a XML file and showing it in two comboboxes ie., cbProduct and cbBrandName

我要显示的文字 cbBrandName 相对于所选文本 cbProduct

I need to show text in cbBrandName with respect to the selected text in cbProduct.

我实现下面的代码：

DataSet ds = new DataSet();
ds.ReadXml(@"..\..\stock.xml");

cbProduct.DataSource = ds.Tables[0].DefaultView.ToTable(true, "productname");
cbProduct.DisplayMember = "productname";

cbBrandName.DataSource = ds.Tables[0].DefaultView.ToTable(true, "brandname");
cbBrandName.DisplayMember = "brandname";

上面的代码是显示所有的文字值 cbBrandName 。如何使它只显示其链接到XML文件中所选择的产品名称列 cbProduct 文本值。

The above code is showing all the text values in cbBrandName. How to make it to show only the text values which are linked to the selected "productname" column of xml file in cbProduct.

请帮助。
结果在此先感谢。

Please Help.
Thanks in Advance.

推荐答案

LINQ看起来更吓人比它。有一个在Anirudha的回答正在使用的这两位，我会试着解释。首先是。选择（X => 这意味着对于列表中的每一件事情，用什么替代它x代表列表中的每个项目

LINQ looks much more scary than it is. There's two bits of it being used in Anirudha's answer, which I'll try to explain. The first is .Select(x=>. This means "For each thing in the list, replace it with something". The x represents each item in the list.

例如：

new string[]{"a", "b", "c"}.Select(x=>x.ToUpper()); 

原来的{A，b，C}，一个数组{A，b，C}组成的数组。它只是说把每个东西的清单，通过调用 ToUpper的（）它不管你得到更换。

turns an array of {"a", "b", "c"}, into an array of {"A", "B", "C"}. It's just saying "Take the each thing in the list, and replace it with whatever you get by calling ToUpper() on it.

LINQ的另一位为。凡（X =方式> 这只是说：给我一个较小的列表，其中只有东西的地方这句话是真的因此，

The other bit of LINQ is .Where(x=>. That just says "Give me a smaller list which only has things where this statement is true". So

new string[]{"a", "b", "c"}.Where(x=>x == "a"); 

会给你{一}清单。更换 X ==A 与 X！=b会给你的{A，C}清单。因此，在代码的第二位，你说：我做那件事，我与它的产品名称替换每个项目之前，我想筛选出任何不符合我想匹配的内容。然后，我改变什么就走了。

will give you a list of {"a"}. Replacing x == "a" with x != "b" will give you a list of {"a", "c"}. So in the second bit of code, you're saying "before I do that thing where I replace each item with its productname, I want to filter out anything that doesn't match what I want to match. Then I transform what's left."

要运用这些代码示例中，我将重新格式化行和评论他们

To apply these to the code example, I'll reformat the lines and comment them.

// To set the first combo box:
cbProduct.Items.AddRange( // Add everything we produce from this to the cbProduct list
    doc.Descendants("items") // For each thing that represents an "items" tag and it's subtags
    .Select(x=>x.Element("productname").Value) // Transform it by getting the "productname" element and reading it's Value.
    .ToArray<string>()); // Then convert that into a string[].


// To set the second combo box:
string product2Search=cbProduct.SelectedItem.ToString();// get the currently selected value of cbProduct.
cbBrandName.Items.Clear(); //clears all items in cbBrandNamedoc
cbBrandName.Items.AddRange( // Add everything we produce from this to the cbBrandName list
  doc.Descendants("items") // For each thing that represents an "items" tag and it's subtags
  .Where(x=>x.Element("productname").Value==product2Search) // Filter our list to only those things where the productname matches what's currently selected in cbProduct (which we just stored)
  .Select(y=>y.Element("brandname").Value) // Transform it by getting the "brandname" element and reading it's Value.
  .ToArray<string>()); // Then convert that into a string[]

是有帮助吗？当我自己的编码，我喜欢把它们放在单独的行这样的分割长LINQ陈述了起来，然后我可以读下来的台词：我得到一个列表，这是真的，那么选择基于这另一件事它，把它变成一个数组。

Is that helpful? When I'm coding myself, I like to split long LINQ statements up by putting them on separate lines like this, and then I can just read down the lines: "I get a list WHERE this is true, then SELECT this other thing based on it, and turn it into an ARRAY."

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