datasette serve --create option, closes #1135

datasette/cli.py

@@ -27,6 +27,7 @@ from .utils import (
     StaticMount,
     ValueAsBooleanError,
 )
+from .utils.sqlite import sqlite3
 from .utils.testing import TestClient
 from .version import __version__
 
@@ -299,7 +300,7 @@ def uninstall(packages, yes):
 
 
 @cli.command()
-@click.argument("files", type=click.Path(exists=True), nargs=-1)
+@click.argument("files", type=click.Path(), nargs=-1)
 @click.option(
     "-i",
     "--immutable",
@@ -401,6 +402,11 @@ def uninstall(packages, yes):
     is_flag=True,
     help="Open Datasette in your web browser",
 )
+@click.option(
+    "--create",
+    is_flag=True,
+    help="Create database files if they do not exist",
+)
 def serve(
     files,
     immutable,
@@ -424,6 +430,7 @@ def serve(
     help_config,
     pdb,
     open_browser,
+    create,
     return_instance=False,
 ):
     """Serve up specified SQLite database files with a web UI"""
@@ -486,6 +493,18 @@ def serve(
         kwargs["config_dir"] = pathlib.Path(files[0])
         files = []
 
+    # Verify list of files, create if needed (and --create)
+    for file in files:
+        if not pathlib.Path(file).exists():
+            if create:
+                sqlite3.connect(file).execute("vacuum")
+            else:
+                raise click.ClickException(
+                    "Invalid value for '[FILES]...': Path '{}' does not exist.".format(
+                        file
+                    )
+                )
+
     try:
         ds = Datasette(files, **kwargs)
     except SpatialiteNotFound:

docs/datasette-serve-help.txt

@@ -40,4 +40,5 @@ Options:
   --help-config             Show available config options
   --pdb                     Launch debugger on any errors
   -o, --open                Open Datasette in your web browser
+  --create                  Create database files if they do not exist
   --help                    Show this message and exit.

tests/test_cli.py

@@ -146,6 +146,7 @@ def test_metadata_yaml():
         help_config=False,
         pdb=False,
         open_browser=False,
+        create=False,
         return_instance=True,
     )
     client = _TestClient(ds)
@@ -221,3 +222,21 @@ def test_sql_errors_logged_to_stderr(ensure_eventloop):
     result = runner.invoke(cli, ["--get", "/:memory:.json?sql=select+blah"])
     assert result.exit_code == 1
     assert "sql = 'select blah', params = {}: no such column: blah\n" in result.stderr
+
+
+def test_serve_create(ensure_eventloop, tmpdir):
+    runner = CliRunner()
+    db_path = tmpdir / "does_not_exist_yet.db"
+    assert not db_path.exists()
+    result = runner.invoke(
+        cli, [str(db_path), "--create", "--get", "/-/databases.json"]
+    )
+    assert result.exit_code == 0, result.output
+    databases = json.loads(result.output)
+    assert {
+        "name": "does_not_exist_yet",
+        "is_mutable": True,
+        "is_memory": False,
+        "hash": None,
+    }.items() <= databases[0].items()
+    assert db_path.exists()