By default, Project Task list displays a project on a daily scale:
Unfortunately, there is no out-of-the-box way of displaying this in a zoomed-out fashion automatically.
I've tried to fish out few ideas over the Internet on how we could work around this and I haven't found any straight forward articles hence, the post.
So, how to workaround this default day scale view automatically?
By scripting of course!
Thankfully, I found useful post from Cees Timmerman on Stack Exchange related to WebPartWPQ2_JSGridController.ZoomOutGantt().
So how to setup the Gantt view to display in month scale?
Add a content editor web part on the bottom of the page (bottom because the page loads from top to bottom and it will be easier if the Gantt view has been loaded first because the script kicks in), edit in HTML mode and paste this script:
<script src="indicate jquery.js location here" type="text/javascript">
$(function(){
setTimeout(function(){
for (var i = 0; i < 3; ++i) WebPartWPQ2_JSGridController.ZoomOutGantt()
}, 2000)
})
</script>
The script zooms out the Gantt view 3 times from default to achieve the month scale view. Once done, hide the content editor web part and save the page.
Sample output:
