What

Adds a new GET /api/v1/prices/grouped_stats endpoint, with mandatory param group_by matching an existing field.

For example, GET /api/v1/prices/grouped_stats?group_by=date&size=2 gives

{
  "items": [
    {
      "date": "2018-03-27",
      "price__count": 24,
      "price__min": 0.47,
      "price__max": 7.8,
      "price__avg": 2.55,
      "price__sum": 61.2
    },
    {
      "date": "2018-03-31",
      "price__count": 13,
      "price__min": 0.54,
      "price__max": 6.49,
      "price__avg": 3.19,
      "price__sum": 41.49
    }
  ],
  "page": 1,
  "pages": 55,
  "size": 2,
  "total": 110
}

Specific time fields are also supported, even though they are not part of the model. Users can group by month, week and year.

Results should be properly paginated.

By default, results are ordered following the group_by parameter (here by date), using the order_by params helps sorting the items with one of the computed param.

For example, GET /api/v1/prices/grouped_stats?group_by=date&size=2&order_by=-price__count gives

{
  "items": [
    {
      "date": "2021-01-11",
      "price__count": 37,
      "price__min": 0.4,
      "price__max": 5.99,
      "price__avg": 2.05,
      "price__sum": 75.8
    },
    {
      "date": "2018-08-09",
      "price__count": 37,
      "price__min": 0.59,
      "price__max": 12.15,
      "price__avg": 2.67,
      "price__sum": 98.71
    }
  ],
  "page": 1,
  "pages": 55,
  "size": 2,
  "total": 110
}

Fixes bug(s)

• Fixes Price stats API: Allow stats to be grouped by specific field #674
• Also fixes Price API: Allow filter on product categories tags #673, en though it could (should) have been a separate PR.

Notes

• This is a pretty hacky implementation of a solution, I'm not really confident about it.
• For example, I had to use OpenApiParameter for it to show up in the docs, which is weird.
• I am also unsure about the performances of these groupings on a production database.