Sitecore patch:instead in config

• Overview
• What is the Issue?
• Working Around the Issue
• Best Practice
  • Example MyPatch.Config
  • Example Result

Overview

During an exercise with our Sitecore configuration we notice a bug with the patch:instead action that is described here: http://sitecore.stackexchange.com/questions/2049/patchinstead-removes-an-element-with-no-attributes

What is the Issue?

When using the patch:instead action and the replacement value is the same, it will cause the xml element to be removed. Here is an example:

Sample patch config contains:

<setting patch:instead="*[@name='Caching.DisableCacheSizeLimits']" name="Caching.DisableCacheSizeLimits" value="false"/>

Existing Sitecore.config setting is:

<setting name="Caching.DisableCacheSizeLimits" value="false" />

This transform will remove the setting from Sitecore / ShowConfig.aspx. If you run into the scenario of missing settings I would start looking here.

Working Around the Issue

How do you work around this issue? There are a couple ways:

1. Delete and replace in config as follows:

    <setting name="Caching.DisableCacheSizeLimits">
            <patch:delete />
    </setting>
    <setting name="Caching.DisableCacheSizeLimits" value="false" />
   

2. Use patch:attribute as follows:

    <setting name="Caching.DisableCacheSizeLimits">
            <patch:attribute name="value">false</patch:attribute>
    </setting>
   

3. Use set:value as follows:

    <setting name="Caching.DisableCacheSizeLimits " set:value="false" />
   

   You will need to make sure that the configuration root node has xmlns:set=”http://www.sitecore.net/xmlconfig/set/”

Best Practice

As preference, we found the 3rd way to be the best option. The reason why we like this approach better than the patch:attribute is primarily to see the patch:source in the showconfig.xml. Doing it the patch:attribute approach does not show the patch:source. This will hide which config file is actually setting the value.

Example MyPatch.Config

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:set="http://www.sitecore.net/xmlconfig/set/">
    <sitecore>
      <setting name="Caching.DisableCacheSizeLimits " set:value="false" />
    </sitecore>
</configuration>

Example Result

This is the result of the above patch config:

<setting name="Caching.DisableCacheSizeLimits" value="false" patch:source="MyPatch.config" />

Notice the additional patch:source attribute.