Completed work on add column (validation etc), closes #4

datasette_edit_schema/__init__.py

@@ -1,5 +1,6 @@
 from datasette import hookimpl
 from datasette.utils.asgi import Response, NotFound, Forbidden
+from datasette.utils import sqlite3
 from urllib.parse import quote_plus, unquote_plus
 import sqlite_utils
 
@@ -210,15 +211,37 @@ async def add_column(request, datasette, database, table, formdata):
     name = formdata["name"]
     type = formdata["type"]
 
+    redirect = Response.redirect(
+        "/-/edit-schema/{}/{}".format(quote_plus(database.name), quote_plus(table))
+    )
+
+    if not name:
+        datasette.add_message(request, "Column name is required", datasette.ERROR)
+        return redirect
+
+    if type.upper() not in REV_TYPES:
+        datasette.add_message(request, "Invalid type: {}".format(type), datasette.ERROR)
+        return redirect
+
     def do_add_column(conn):
         db = sqlite_utils.Database(conn)
-        db[table].add_column(name, type)
+        db[table].add_column(name, REV_TYPES[type.upper()])
 
-    await datasette.databases[database.name].execute_write_fn(do_add_column, block=True)
+    error = None
+    try:
+        await datasette.databases[database.name].execute_write_fn(
+            do_add_column, block=True
+        )
+    except sqlite3.OperationalError as e:
+        if "duplicate column name" in str(e):
+            error = "A column called '{}' already exists".format(name)
+        else:
+            error = str(e)
 
-    return Response.redirect(
-        "/{}/{}".format(quote_plus(database.name), quote_plus(table))
-    )
+    if error:
+        datasette.add_message(request, error, datasette.ERROR)
+
+    return redirect
 
 
 async def rename_table(request, datasette, database, table, formdata):

tests/test_edit_schema.py

@@ -83,7 +83,7 @@ async def test_delete_table(db_path):
 @pytest.mark.asyncio
 @pytest.mark.parametrize(
     "col_type,expected_type",
-    [("text", str), ("integer", int), ("float", float), ("blob", bytes)],
+    [("text", str), ("integer", int), ("real", float), ("blob", bytes)],
 )
 async def test_add_column(db_path, col_type, expected_type):
     ds = Datasette([db_path])
@@ -110,13 +110,56 @@ async def test_add_column(db_path, col_type, expected_type):
             cookies=cookies,
         )
     assert 302 == response.status_code
+    if "ds_messages" in response.cookies:
+        messages = ds.unsign(response.cookies["ds_messages"], "messages")
+        # None of these should be errors
+        assert all(m[1] == Datasette.INFO for m in messages), "Got an error: {}".format(
+            messages
+        )
     assert {
         "name": str,
         "description": str,
         "new_col": expected_type,
     } == table.columns_dict
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "name,type,expected_error",
+    [
+        ("name", "text", "A column called 'name' already exists"),
+        ("", "text", "Column name is required"),
+        ("]]]", "integer", 'unrecognized token: "]"'),
+        ("name", "blop", "Invalid type: blop"),
+    ],
+)
+async def test_add_column_errors(db_path, name, type, expected_error):
+    ds = Datasette([db_path])
+    cookies = {"ds_actor": ds.sign({"a": {"id": "root"}}, "actor")}
+    async with httpx.AsyncClient(app=ds.app()) as client:
+        csrftoken = (
+            await client.get(
+                "http://localhost/-/edit-schema/data/creatures", cookies=cookies
+            )
+        ).cookies["ds_csrftoken"]
+        response = await client.post(
+            "http://localhost/-/edit-schema/data/creatures",
+            data={
+                "add_column": "1",
+                "name": name,
+                "type": type,
+                "csrftoken": csrftoken,
+            },
+            allow_redirects=False,
+            cookies=cookies,
+        )
+    response.status_code == 302
+    assert response.headers["location"] == "/-/edit-schema/data/creatures"
+    messages = ds.unsign(response.cookies["ds_messages"], "messages")
+    assert len(messages) == 1
+    assert messages[0][0] == expected_error
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize(
     "post_data,expected_columns_dict,expected_order",