support group by multiple fields

docs/charts.rst

@@ -79,6 +79,62 @@ Response
  - ``html`` format response is a html, javascript and css to the chart
  - ``json`` format response is the ``JSON`` data that can be passed to a charting library
 
+Get a chart for field grouped by another field in the form
+----------------------------------------------------------
+
+- ``field_name`` - a field name in the form, for group by multiple fields
+  requires this to be a numeric field.
+- ``group_by`` - a field name in the form to group by, if it is a comma
+  separated field list then the field_name will be grouped by all the fields in
+  the list.
+- ``format`` - can be ``html`` or ``json``
+
+.. raw:: html
+
+    <pre class="prettyprint">
+    <b>GET</b> /api/v1/charts/<code>{formid}</code>.<code>{format}</code>?field_name=<code>field_name</code>&group_by=<code>field1,field2</code></pre>
+
+Example
+^^^^^^^
+::
+
+    curl -X GET https://api.ona.io/api/v1/charts/4240.json?field_name=age&group_by=year
+    curl -X GET https://api.ona.io/api/v1/charts/4240.json?field_name=age&group_by=sex,year
+
+Response
+^^^^^^^^
+
+ - ``html`` format response is a html, javascript and css to the chart
+ - ``json`` format response is the ``JSON`` data that can be passed to a charting library
+
+ .. raw:: json
+
+    {
+    "field_type": "integer",
+    "data_type": "numeric",
+    "field_xpath": "age",
+    "data": [
+        {
+        "mean": 45.0,
+        "sum": 855.0,
+        "year": "1880",
+        "sex": [
+            "Female"
+        ]
+        },
+        {
+        "mean": 45.0,
+        "sum": 855.0,
+        "year": "1850",
+        "sex": [
+            "Female"
+        ]
+        },
+    "field_label": "Age",
+    "field_name": "age",
+    "xform": 4240
+    }
+
 Get a chart data for all fields in a form
 ------------------------------------------
 
@@ -103,4 +159,4 @@ Response
 
  - `json` format response is the `JSON` data for each field that can be passed to a charting library
 
-    
+

onadata/libs/data/query.py

@@ -101,12 +101,25 @@ def _postgres_aggregate_group_by(field, name, xform, group_by, data_view=None):
     if data_view:
         additional_filters = _additional_data_view_filters(data_view)
 
-    query = "SELECT %(group_by)s AS \"%(group_name)s\","\
+    group_by_select = ""
+    group_by_group_by = ""
+    if isinstance(group_by, list):
+        group_by_group_by = []
+        for i, v in enumerate(group_by):
+            group_by_select += "%(group_by" + str(i) + \
+                    ")s AS \"%(group_name" + str(i) + ")s\", "
+            group_by_group_by.append("%(group_by" + str(i) + ")s")
+        group_by_group_by = ",".join(group_by_group_by)
+    else:
+        group_by_select = "%(group_by)s AS \"%(group_name)s\","
+        group_by_group_by = "%(group_by)s"
+
+    query = "SELECT " + group_by_select + \
             "SUM((%(json)s)::numeric) AS sum, " \
             "AVG((%(json)s)::numeric) AS mean  " \
             "FROM %(table)s WHERE %(restrict_field)s=%(restrict_value)s " \
             "AND deleted_at IS NULL " + additional_filters + \
-            " GROUP BY %(group_by)s"
+            " GROUP BY " + group_by_group_by
 
     query = query % string_args
 
@@ -122,15 +135,23 @@ def _postgres_select_key(field, name, xform):
 
 
 def _query_args(field, name, xform, group_by=None):
-    return {
+    qargs = {
         'table': 'logger_instance',
         'json': _json_query(field),
         'name': name,
-        'group_name': group_by,
-        'group_by': _json_query(group_by),
         'restrict_field': 'xform_id',
         'restrict_value': xform.pk}
 
+    if isinstance(group_by, list):
+        for i, v in enumerate(group_by):
+            qargs['group_name%d' % i] = v
+            qargs['group_by%d' % i] = _json_query(v)
+    else:
+        qargs['group_name'] = group_by
+        qargs['group_by'] = _json_query(group_by)
+
+    return qargs
+
 
 def _select_key(field, name, xform):
     if using_postgres: