Export option: _shape=array&_nl=on for newline-delimited JSON

datasette/templates/table.html

@@ -140,7 +140,13 @@
 {% if display_rows %}
     <div id="export" class="advanced-export">
         <h3>Advanced export</h3>
-        <p>JSON shape: <a href="{{ url_json }}">default</a>, <a href="{{ append_querystring(url_json, '_shape=array') }}">array</a>{% if primary_keys %}, <a href="{{ append_querystring(url_json, '_shape=object') }}">object</a>{% endif %}</p>
+        <p>JSON shape:
+            <a href="{{ url_json }}">default</a>,
+            <a href="{{ append_querystring(url_json, '_shape=array') }}">array</a>,
+            <a href="{{ append_querystring(url_json, '_shape=array&_nl=on') }}">newline-delimited</a>{% if primary_keys %},
+                <a href="{{ append_querystring(url_json, '_shape=object') }}">object</a>
+            {% endif %}
+        </p>
         <form action="{{ url_csv_path }}" method="get">
             <p>
                 CSV options:

datasette/views/base.py

@@ -432,10 +432,18 @@ class BaseView(RenderMixin):
             headers = {}
             if self.ds.cors:
                 headers["Access-Control-Allow-Origin"] = "*"
+            # Handle _nl option for _shape=array
+            nl = request.args.get("_nl", "")
+            if nl and shape == "array":
+                body = "\n".join(json.dumps(item) for item in data)
+                content_type = "text/plain"
+            else:
+                body = json.dumps(data, cls=CustomJSONEncoder)
+                content_type = "application/json"
             r = response.HTTPResponse(
-                json.dumps(data, cls=CustomJSONEncoder),
+                body,
                 status=status_code,
-                content_type="application/json",
+                content_type=content_type,
                 headers=headers,
             )
         else:

docs/json_api.rst

@@ -61,11 +61,12 @@ 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
+* ``?_shape=array`` - an JSON array of objects
+* ``?_shape=array&_nl=on`` - a newline-separated list of JSON objects
+* ``?_shape=arrayfirst`` - a flat JSON array containing just the first value from each row
+* ``?_shape=object`` - a JSON object keyed using the primary keys of the rows
 
-``objects`` looks like this::
+``_shape=objects`` looks like this::
 
     {
         "database": "sf-trees",
@@ -86,7 +87,7 @@ options:
         ]
     }
 
-``array`` looks like this::
+``_shape=array`` looks like this::
 
     [
         {
@@ -103,11 +104,17 @@ options:
         }
     ]
 
-``arrayfirst`` looks like this::
+``_shape=array&_nl=on`` looks like this::
+
+    {"id": 1, "value": "Myoporum laetum :: Myoporum"}
+    {"id": 2, "value": "Metrosideros excelsa :: New Zealand Xmas Tree"}
+    {"id": 3, "value": "Pinus radiata :: Monterey Pine"}
+
+``_shape=arrayfirst`` looks like this::
 
     [1, 2, 3]
 
-``object`` looks like this::
+``_shape=object`` looks like this::
 
     {
         "1": {
@@ -140,6 +147,9 @@ querystring arguments:
 ``?_shape=SHAPE``
     The shape of the JSON to return, documented above.
 
+``?_nl=on``
+    When used with ``?_shape=array`` produces newline-delimited JSON objects.
+
 ``?_json=COLUMN1&_json=COLUMN2``
     If any of your SQLite columns contain JSON values, you can use one or more
     ``_json=`` parameters to request that those columns be returned as regular

tests/test_api.py

@@ -9,6 +9,7 @@ from .fixtures import ( # noqa
     make_app_client,
     METADATA,
 )
+import json
 import pytest
 import urllib
 
@@ -547,6 +548,27 @@ def test_table_shape_array(app_client):
     }] == response.json
 
 
+def test_table_shape_array_nl(app_client):
+    response = app_client.get(
+        '/fixtures/simple_primary_key.json?_shape=array&_nl=on'
+    )
+    lines = response.text.split("\n")
+    results = [json.loads(line) for line in lines]
+    assert [{
+        'id': '1',
+        'content': 'hello',
+    }, {
+        'id': '2',
+        'content': 'world',
+    }, {
+        'id': '3',
+        'content': '',
+    }, {
+        'id': '4',
+        'content': 'RENDER_CELL_DEMO',
+    }] == results
+
+
 def test_table_shape_invalid(app_client):
     response = app_client.get(
         '/fixtures/simple_primary_key.json?_shape=invalid'

tests/test_html.py

@@ -422,6 +422,7 @@ def test_table_csv_json_export_interface(app_client):
     assert [
         "simple_primary_key.json?id__gt=2",
         "simple_primary_key.json?id__gt=2&_shape=array",
+        "simple_primary_key.json?id__gt=2&_shape=array&_nl=on",
         "simple_primary_key.json?id__gt=2&_shape=object"
     ] == json_links
     # And the CSV form
@@ -796,7 +797,7 @@ def test_advanced_export_box(app_client, path, has_object, has_stream, has_expan
     assert response.status == 200
     soup = Soup(response.body, "html.parser")
     # JSON shape options
-    expected_json_shapes = ["default", "array"]
+    expected_json_shapes = ["default", "array", "newline-delimited"]
     if has_object:
         expected_json_shapes.append("object")
     div = soup.find("div", {"class": "advanced-export"})