Before this commit, composing multiple category filters with a query such as category:category1 and category:category2 would not return any results. This is because we were filtering for topics that belonged to both category1 and category2, which is impossible since a topic can only belong to a single category.
With this commit, specifying a query like category:category1 category:category2 will now translate to filtering for topics that belong to either the category1 or category2 category.
This commit adds support for filtering for topics in specific
subcategories via the categories filter query language.
For example: `category:documentation:admins` will filter for topics and
subcategory topics in
the category with slug "admins" whose parent category has the slug
"documentation".
The `=` prefix can also be used such that
`=category:documentation:admins` will exclude subcategory topics of the
category with slug "admins" whose parent category has the slug
"documentation".
On the `/filter` route, the categories filtering query language is now
supported in the input per the example provided below:
```
category:bug => topics in the bug category AND all subcategories
=category:bug => topics in the bug category excluding subcategories
category:bug,feature => allow for categories either in bug or feature
=category:bug,feature => allow for exact categories match excluding sub cats
categories: => alias for category
```
Currently composing multiple category filters is not supported as we
have yet to determine what behaviour it should result in. For example,
`category:bug category:feature` would now return topics that are in both
the `bug` and `feature` category but it is not possible for a topic to
belong to two categories.
The following are the changes being introduced in this commit:
1. Instead of mapping the query language to various query params on the
client side, we've decided that the benefits of having a more robust
query language far outweighs the benefits of having a more human readable query params in the URL.
As such, the `/filter` route will just accept a single `q` query param
and the query string will be parsed on the server side.
1. On the `/filter` route, the tags filtering query language is now
supported in the input per the example provided below:
```
tags:bug+feature tagged both bug and feature
tags:bug,feature tagged either bug or feature
-tags:bug+feature excluding topics tagged bug and feature
-tags:bug,feature excluding topics tagged bug or feature
```
The `tags` filter can also be specified multiple
times in the query string like so `tags:bug tags:feature` which will
filter topics that contain both the `bug` tag and `feature` tag. More
complex query like `tags:bug+feature -tags:experimental` will also work.
This change sets the ground work for allowing us to filter topics list
by tags in the following ways:
1. Filter for topics that matches all tags in a given set of tags
2. Filter for topics that matches any tags in a given set of tags
3. Exclude topics that matches all tags in a given set of tags
4. Exclude topics that matches any tags in a given set of tags
Alan Guo Xiang Tan