Filtering for Things

[s-kostyuk]

Implement a support of filtering for Things (items in /things/ REST API endpoint).

Parameter-based filtering is proposed. To filter all things by their placement, the following request will be able to be used:

curl --request GET \
  --url 'http://dpl_host:dpl_port/things/?placement=R1' \
  --header 'Authorization: your_auth_token_here'

In support of filtering approach, based on query parameters, see the following descriptions and mentions:

• in GitHub documentation
• in "Web API Design" e-book
• on Hackernoon: article
• and also here and here

[s-kostyuk]

But query parameter-based approach have its own issues. For example:

• collisions are possible if objects in filtered collection have fields called like page, fields, sort, direction and at the same time those parameters are used for service tasks like pagination, field selection, result sorting and so on;
• it's unclear what to do with requests which have a parameter that doesn't correspond neither to a set of service parameters or to field names of objects;
• some approach is needed to address two mentioned issues;
• one of those approaches is a usage of whitelist of allowed filters (like in django), but whitelist checking will affect an overall request processing speed.

From this perspective, it's much easier to parse exactly one filter statement specified in single filter parameter (like in OData) than to parse all query parameters and to build some filtering expressions based on them.

[s-kostyuk]

Base support implemented in https://github.com/s-kostyuk/adpl/pull/20. If you need any additional filtering by other fields, updated_since filtering, pagination and complex search - please, let me know by endorsing this comment and/or by creating of a new comment in this issue.