I am using Rails5.2 and read project code like
blog = Blog.includes(:posts).references(:posts).where(uuid: params[:uuid])
When I searched on the internet, I got examples like link
Blog.includes(:posts).where(name: 'Blog 1').references(:posts)
Are there any differences for placing where clause before or after references clause?
You should read joins, includes, preload, eager_load & references from reference
Note: includes do not create separate query always.
references is used after includes & before where clause (I used while migrating project from rails-3 to rails-5 to resolve column ambiguity issue)
Read this also.
If you check this link here, you can see the definition of references.
In short terms, the includes will run a separate query to get all your posts (in your example) instead of getting them every time you loop through a blog.
Now for references, of you want to add a where condition on the posts, you'll need to add it. In your case, you don't need to include it.
Small example:
blog = Blog.includes(:posts).where(uuid: params[:uuid]) -> will run a query to get the Blog from blogs and a query to get all the posts related to this blog.
In another case, like this: blog = Blog.includes(:posts).references(:posts).where(posts: { name: 'test' }) you'll have to use the references or your where condition will throw an error
