Subtring Expression returning only the end of a variable

[AdamEv31]

Hi all, 

Just wondering if anyone can help. I am trying to create an expression that will remove the file extension from the end of a file URL, as an example if the URL field being parsed is: 'https://mytenant.sharepoint.com/sites/sitecol/doclib/filename.ext' I would want to remove '.ext'. 

I know I can use the replace expression but the URL's are going to constantly change as these are coming from a SharePoint list therefore I need to write an expression, as an example I have the following:

substring(triggerOutputs()?['body/FileRelativeUrl'], lastIndexOf(triggerOutputs()?['body/FileRelativeUrl'], '.'), sub(length(triggerOutputs()?['body/FileRelativeUrl']), lastIndexOf(triggerOutputs()?['body/FileRelativeUrl'], '.')))

However this is returning '.ext' instead of the start of the url as I require, how do I get the start of the URL instead. 

Any help is appreciated. 

[Paulie78 · Accepted solution]

I think you want:

substring(triggerOutputs()?['body/FileRelativeUrl'], 0, lastIndexOf(triggerOutputs()?['body/FileRelativeUrl'], '.'))