更改属性值的一部分 [英] Change part of an attribute value

问题描述

我想使用 Powershell 更改 web.config 文件中连接字符串的一部分.

我可以使用以下代码读取所需的连接字符串:

[xml]$XmlDoc = Get-Content C:\...\Web.config$ConString = $XmlDoc.configuration.connectionStrings.add.connectionString[0]

并提取正确的值:

<前>服务器=testDB01\sql14;uid=abc;pwd=def;database=ghi;language=english

现在我想更改="之后的部分以根据需要调整值.我可以通过将文本分成部分来访问这些值，例如

$ConString.Split(";")[0].Split("\")[1]

返回

<前>sql14

我现在如何更改该值并将其保存到文件中?

解决方案

这是一个使用 -replace 运算符 来替换连接字符串中的数据库名称:

^{有关下面 -regex 使用的正则表达式的说明，请参阅 https://regex101.com/r/Va3XN7/1 - 请注意，这是否有效取决于您浏览器的 JavaScript 引擎；例如，它适用于 Chrome，但可能不适用于 Firefox.PowerShell 使用 .NET 正则表达式，在本例中，其行为与(现代)JavaScript 相同.}

注意:

• 正如 Ansgar Wiechers 在评论中指出的那样，点符号 深入到 XML 文档(例如，$XmlDoc.configuration.connectionStrings.add.connectionString[0])很方便，但有局限性:它不适合对 XML 文档进行结构性更改.

  • 要执行结构更改，您必须直接使用基础System.Xml.XmlNode[-derived] 类型.

• 但是，对于简单的非结构性更改(包括这种情况)，点表示法可用于进行更新，即:

  • 更改 leaf 元素的文本内容.
  • 更改属性(层次结构中的任何位置)的值 - 如本例所示.

• 点表示法的一个普遍缺陷是可能与基础类型的成员发生名称冲突 - 请参阅这个答案.

# 创建一个示例 XML 文件.@'<?xml version="1.0"?><配置><连接字符串><添加><connectionString server="server=testDB01\sql14;uid=abc;pwd=def;database=ghi;language=english"/><connectionString server="..."/></添加></connectionStrings></配置>'@ >测试文件# 将文件读入 XML 文档.[xml] $xmlDoc = Get-Content -Raw test.xml# 更新第一个的'server'属性；元素:# 用'sql999'替换现有的数据库名称$element = $xmlDoc.configuration.connectionStrings.add.connectionString[0]$element.server = $element.server -replace '(?<=\bserver=.+?\\).+?(?=;)', 'sql999'# 将修改后的文档保存回文件中.# 注意:这里使用无 BOM 的 UTF-8 编码.# Convert-Path 确保将完整路径传递给 .Save() 方法，# 因为 .NET 的当前目录通常与 PowerShell 的不同$xmlDoc.Save((Convert-Path test.xml))# 输出更新的内容:获取内容 test.xml

以上产生以下结果 - 注意 sql14 是如何被 sql999 替换的:

<配置><连接字符串><添加><connectionString server="server=testDB01\sql999;uid=abc;pwd=def;database=ghi;language=english"/><connectionString server="..."/></添加></connectionStrings></配置>

I want to change a part of a connection string within an web.config file with Powershell.

I can read the desired connection string with the following code:

[xml]$XmlDoc = Get-Content C:\...\Web.config
$ConString = $XmlDoc.configuration.connectionStrings.add.connectionString[0]

and get the proper value extracted:

server=testDB01\sql14;uid=abc;pwd=def;database=ghi;language=english

Now I want to change the parts after the "=" to adapt the values as needed. I can access the values by spliting the text into part with e.g.

$ConString.Split(";")[0].Split("\")[1]

that returns

sql14

How can I now change that value and save it to the file?

解决方案

Here's a self-contained example that uses the -replace operator to replace the database name in your connection string:

^{For an explanation of the regular expression used with -regex below, see https://regex101.com/r/Va3XN7/1 - note that whether that works depends on your browser's JavaScript engine; e.g., it works in Chrome, but may not work in Firefox. PowerShell uses .NET regular expressions, which, in this instance, behave the same as (modern) JavaScript's.}

Note:

• As Ansgar Wiechers points out in a comment, dot notation to drill into an XML document (e.g., $XmlDoc.configuration.connectionStrings.add.connectionString[0]) is convenient, but has limitations: it isn't suited to making structural changes to XML documents.

  • To perform structural changes, you must work directly with the methods of the underlying System.Xml.XmlNode[-derived] types.

• However, for simple, non-structural changes (which includes this case), dot notation can be used to make updates, namely:

  • Changing the text content of a leaf element.
  • Changing the value of an attribute (anywhere in the hierarchy) - as in this case.

• A general pitfall with dot notation is the potential for name collisions with the members of the underlying types - see this answer.

# Create a sample XML file.
@'
<?xml version="1.0"?>
<configuration>
    <connectionStrings>
        <add>
            <connectionString server="server=testDB01\sql14;uid=abc;pwd=def;database=ghi;language=english" />
            <connectionString server="..." />
        </add>
    </connectionStrings>
</configuration>
'@ > test.xml

# Read the file into an XML document.
[xml] $xmlDoc = Get-Content -Raw test.xml

# Update the 'server' attribute of the first <connectionString> element:
# Replace the existing db name with 'sql999'
$element = $xmlDoc.configuration.connectionStrings.add.connectionString[0]
$element.server = $element.server -replace '(?<=\bserver=.+?\\).+?(?=;)', 'sql999'

# Save the modified document back to the file.
# Note: This uses BOM-less UTF-8 encoding.
#       Convert-Path ensures that a full path is passed to the .Save() method,
#       because .NET's current directory typically differ from PowerShell's
$xmlDoc.Save((Convert-Path test.xml))

# Output the updated content:
Get-Content test.xml

The above yields the following - note how sql14 was replaced with sql999:

<?xml version="1.0"?>
<configuration>
  <connectionStrings>
    <add>
      <connectionString server="server=testDB01\sql999;uid=abc;pwd=def;database=ghi;language=english" />
      <connectionString server="..." />
    </add>
  </connectionStrings>
</configuration>

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