Pagination with per-row access rights - pagination

Question

Hi I am using CouchDB and assuming I have an articles document with the field users, containing an array of user IDs that are allowed to view this article.
Example scenario, there will be a paginated table view showing 10 articles per page, my controller will retrieve the first 10 articles from CouchDB then perform the access rights check one by one on the returned articles. But the current user may only have view access rights on say, 8 of them, therefore the table will only show 8 articles instead of 10.
What are the best practice of handling such situation besides implementing the access rights logic on the CouchDB layer?

Answer 1

To accomplish this, I would simply use a view keyed on the users field:
function (doc) {
doc.users.forEach(function (user) {
emit([ user ]);
});
}
I emitted an array with just 1 item in this case. I presume you'd also emit something like doc.created in order to have your articles sorted, you would simply add them after user in that array.
The view results would look something like:
{
"rows": [
{ "id": "<article-1>", "key": [ "<user-1>", "<created>" ] },
{ "id": "<article-2>", "key": [ "<user-1>", "<created>" ] },
{ "id": "<article-3>", "key": [ "<user-1>", "<created>" ] },
{ "id": "<article-1>", "key": [ "<user-2>", "<created>" ] },
{ "id": "<article-1>", "key": [ "<user-3>", "<created>" ] }
]
}
You can simply paginate like you normally would with CouchDB. You simply use start_key=["<user-1>"]&end_key=["<user-1>","\ufff0"] in addition to the usual paging limit=10&skip=0 for page 1, limit=10&skip=10 for page 2, etc.