How is the site context language determined and is there a priority to which is chosen?

Question

The other day a colleague was asking about the sc_lang query string parameter and how Sitecore knows to use that for the language. The conversation was seeking answers to the following questions:

• What are all the ways in which Sitecore determines which language to use?
• What is the order of priority for each method in relation to the other?
• Is there a way to include other procedures to determine the language?

Answer 1

I think this is well covered on John West's post which in summary describes what the priority is and how Sitecore handles them:

"The Sitecore layout engine retrieves content from the Sitecore repository in the context language (Sitecore.Context.Language). The default logic to determine the context language is to use the first of these variables that specifies a value:

1. The sc_lang query string parameter.

   https://www.company.com/about-us/?sc_lang=en

2. The language prefix in the path in the requested URL.

   https://www.company.com/en/about-us/

3. The language cookie associated with the context site.

   company#lang

4. The default language associated with the context logical site.

<site name="company" patch:before="site[@name='website']" 
    virtualFolder="/" physicalFolder="/" 
    rootPath="/sitecore/content/company" language="en" 
    hostName="www.company.com" />

5. The DefaultLanguage setting specified in web.config.

<setting name="DefaultLanguage" value="en" />

References:

• Community Site - John West
• Sitecore Corner