'sqlite-utils add-column name type' command, closes #15

docs/cli.rst

@@ -221,6 +221,17 @@ After running the above ``dogs.json`` example, try running this::
 
 This will replace the record for id=2 (Pancakes) with a new record with an updated age.
 
+.. _cli_add_column:
+
+Adding columns
+==============
+
+You can add a column using the ``add-column`` command::
+
+    $ sqlite-utils add-column mydb.db mytable nameofcolumn text
+
+The last argument here is the type of the column to be created. You can use one of ``text``, ``integer``, ``float`` or ``blob``.
+
 .. _cli_create_index:
 
 Creating indexes

sqlite_utils/cli.py

@@ -134,6 +134,26 @@ def optimize(path, no_vacuum):
         db.vacuum()
 
 
+@cli.command(name="add-column")
+@click.argument(
+    "path",
+    type=click.Path(exists=True, file_okay=True, dir_okay=False, allow_dash=False),
+    required=True,
+)
+@click.argument("table")
+@click.argument("col_name")
+@click.argument(
+    "col_type",
+    type=click.Choice(
+        ["integer", "float", "blob", "text", "INTEGER", "FLOAT", "BLOB", "TEXT"]
+    ),
+)
+def add_column(path, table, col_name, col_type):
+    "Add a column to the specified table"
+    db = sqlite_utils.Database(path)
+    db[table].add_column(col_name, col_type)
+
+
 @cli.command(name="create-index")
 @click.argument(
     "path",

tests/test_cli.py

@@ -6,6 +6,8 @@ import os
 import pytest
 import sqlite3
 
+from .utils import collapse_whitespace
+
 
 CREATE_TABLES = """
 create table Gosh (c1 text, c2 text, c3 text);
@@ -170,6 +172,44 @@ def test_create_index(db_path):
     )
 
 
+@pytest.mark.parametrize(
+    "col_name,col_type,expected_schema",
+    (
+        ("text", "TEXT", "CREATE TABLE [dogs] ( [name] TEXT , [text] TEXT)"),
+        (
+            "integer",
+            "INTEGER",
+            "CREATE TABLE [dogs] ( [name] TEXT , [integer] INTEGER)",
+        ),
+        ("float", "FLOAT", "CREATE TABLE [dogs] ( [name] TEXT , [float] FLOAT)"),
+        ("blob", "blob", "CREATE TABLE [dogs] ( [name] TEXT , [blob] BLOB)"),
+    ),
+)
+def test_add_column(db_path, col_name, col_type, expected_schema):
+    db = Database(db_path)
+    db.create_table("dogs", {"name": str})
+    assert "CREATE TABLE [dogs] ( [name] TEXT )" == collapse_whitespace(
+        db["dogs"].schema
+    )
+    assert (
+        0
+        == CliRunner()
+        .invoke(cli.cli, ["add-column", db_path, "dogs", col_name, col_type])
+        .exit_code
+    )
+    assert expected_schema == collapse_whitespace(db["dogs"].schema)
+
+
+def test_add_column_error_invalid_type(db_path):
+    db = Database(db_path)
+    db.create_table("dogs", {"name": str})
+    result = CliRunner().invoke(
+        cli.cli, ["add-column", db_path, "dogs", "blah", "badtype"]
+    )
+    assert 0 != result.exit_code
+    assert 'Invalid value for "col_type"' in result.output
+
+
 def test_enable_fts(db_path):
     assert None == Database(db_path)["Gosh"].detect_fts()
     result = CliRunner().invoke(

tests/test_create.py

@@ -4,9 +4,10 @@ import datetime
 import json
 import pathlib
 import pytest
-import re
 import sqlite3
 
+from .utils import collapse_whitespace
+
 try:
     import pandas as pd
 except ImportError:
@@ -364,10 +365,3 @@ def test_create_table_numpy(fresh_db):
             "np.uint8": 8,
         }
     ] == list(fresh_db["types"].rows)
-
-
-COLLAPSE_RE = re.compile("\s+")
-
-
-def collapse_whitespace(s):
-    return COLLAPSE_RE.sub(" ", s)

tests/utils.py

@@ -0,0 +1,7 @@
+import re
+
+COLLAPSE_RE = re.compile(r"\s+")
+
+
+def collapse_whitespace(s):
+    return COLLAPSE_RE.sub(" ", s)