?_shape=arrayfirst, closes #287

datasette/views/base.py

@@ -185,7 +185,9 @@ class BaseView(RenderMixin):
 
             # Deal with the _shape option
             shape = request.args.get("_shape", "arrays")
-            if shape in ("objects", "object", "array"):
+            if shape == "arrayfirst":
+                data = [row[0] for row in data["rows"]]
+            elif shape in ("objects", "object", "array"):
                 columns = data.get("columns")
                 rows = data.get("rows")
                 if rows and columns:

docs/json_api.rst

@@ -62,6 +62,7 @@ options:
 * ``?_shape=arrays`` - ``"rows"`` is the default option, shown above
 * ``?_shape=objects`` - ``"rows"`` is a list of JSON key/value objects
 * ``?_shape=array`` - the entire response is an array of objects
+* ``?_shape=arrayfirst`` - the entire response is a flat JSON array containing just the first value from each row
 * ``?_shape=object`` - the entire response is a JSON object keyed using the primary keys of the rows
 
 ``objects`` looks like this::
@@ -102,6 +103,10 @@ options:
         }
     ]
 
+``arrayfirst`` looks like this::
+
+    [1, 2, 3]
+
 ``object`` looks like this::
 
     {

tests/test_api.py

@@ -433,6 +433,17 @@ def test_table_shape_arrays(app_client):
     ] == response.json['rows']
 
 
+def test_table_shape_arrayfirst(app_client):
+    response = app_client.get(
+        '/test_tables.json?' + urllib.parse.urlencode({
+            'sql': 'select content from simple_primary_key order by id',
+            '_shape': 'arrayfirst'
+        }),
+        gather_request=False
+    )
+    assert ['hello', 'world', ''] == response.json
+
+
 def test_table_shape_objects(app_client):
     response = app_client.get(
         '/test_tables/simple_primary_key.json?_shape=objects',