How do I conditionally turn off pre-render for 2 Blazor pages

Question

Hi all;

I have a Blazor InteractiveServer application using .NET 8.

The Google web crawler gets just the static html for a page, not waiting for Blazor to create the SignalR circuit and therefor not waiting for OnInitializeAsync() to read from the DB and populate the page.

I have 2 pages that I need to have indexed with their full content. These pages are unique due to a parameter in the url ?id=123 and the sitemap.txt lists thousands of these 2 pages.

My question is first, how do I determine if the page is being read by a crawler? (And if this is not possible, then I can always have these 2 pages in the fully render on first request mode.)

And second, how do I then put that page in a render mode where what is first returned is the fully populated page as static HTML.

It's fine if after the page is fully rendered as static HTML it then re-renders it again as an interactive page with SignalR set up.

I have found this info on pre-rendering, but it's not clear where it goes or if this is what I need. And nothing about how to only do it if a crawler has requested a page.

thanks - dave

Answer 1

There are two ways to detect the crawler.

check the user agent,

https://developers.google.com/search/docs/crawling-indexing/overview-google-crawlers

Include a parameter on sitemap links and robots.txt.

note: you do not want to turn off pre-render, but query and display the data in pre-render. The crawler can only access pre-render. If you turned off pre-render, it would only see the host page without any Blazor content.