Enhanced filtering abilities in the API

Introduce new operators and let user combine filters.

doc/20.api.md

@@ -8,3 +8,70 @@ API token (see the doc about deployment for more infos).
 A helper script is available under `scripts/api_doc.py` to export a
 documentation of the available API endpoints and usage in the current version
 of the code.
+
+
+### Pagination
+
+All the API endpoints support pagination. By default, no pagination is done.
+You can force pagination specifying a `page[size]` GET parameter to specify a
+number of items per page and a `page[number]` GET parameter to specify the
+page to return. Pages are numbered starting from zero.
+
+For instance,
+
+```
+> GET /api/v1/reports?page[size]=10&page[number]=0
+```
+
+will return the ten first reports of the first page, which are the ten first
+reports from the database.
+
+
+### Filtering
+
+#### Basic filtering
+
+Filtering is possible in the API through the use of a `filter` GET parameter.
+
+You can filter on a given field value using the parameter value
+`filter[FIELD]=VALUE`. For instance,
+
+```
+> GET /api/v1/reports?filter[id]=1
+```
+
+will return the reports with `id` 1.
+
+#### Combining filters
+
+All provided filters must be filled for an item to be returned. That is, if
+you want to return all the reports of type `interrupt` with no `upvotes`, you
+can use
+
+```
+> GET /api/v1/reports?filter[type]=interrupt&filter[upvotes]=0
+```
+
+If you want to make an `OR` condition, satisfying either one of the filters,
+you should make two different API calls.
+
+
+#### Commplex filtering
+
+You can also use more complex elaborations through the syntax
+`filter[FIELD][OPERATION]=VALUE`. The available operations are `eq` (equal,
+default operation), `ne` (not equal), `gt` (greater than), `ge` (greater or
+equal), `lt` (lower than) and `le` (lower or equal). For instance,
+
+```
+> GET /api/v1/reports?filter[id][ne]=1
+```
+
+will return all the reports except the one with `id` 1.
+
+With the filters combination capability, you can use this to get all the
+reports in a geographical bounding box:
+
+```
+> GET /api/v1/reports?filter[lat][gt]=LAT_MIN&filter[lat][lt]=LAT_MAX&filter[lng][gt]=LNG_MIN&filter[lng][lt]=LNG_MAX
+```

server/jsonapi.py

@@ -10,7 +10,7 @@ import re
 
 import bottle
 
-FILTER_RE = re.compile(r"filter\[([A-z0-9_]+)\]")
+FILTER_RE = re.compile(r"filter\[([A-z0-9_]+?)\](\[([A-z0-9_]+)\])?")
 
 
 class DateAwareJSONEncoder(json.JSONEncoder):
@@ -73,8 +73,23 @@ def JsonApiParseQuery(query, model, default_sorting=None):
         if not filter_match:
             continue
         field = getattr(model, filter_match.group(1))
-        value = query[filter_match.group(0)]
-        filters.append(field == value)
+        for value in query.getall(param):
+            # Handle operation
+            operation = filter_match.group(3)
+            if operation == 'eq' or operation is None:
+                filters.append(field == value)
+            elif operation == 'ne':
+                filters.append(field != value)
+            elif operation == 'gt':
+                filters.append(field > value)
+            elif operation == 'ge':
+                filters.append(field >= value)
+            elif operation == 'lt':
+                filters.append(field < value)
+            elif operation == 'le':
+                filters.append(field <= value)
+            else:
+                raise ValueError("Invalid filtering operator provided.")
 
     # Handle pagination according to JSON API spec
     page_number, page_size = 0, None