'sqlite-utils triggers' command, closes #218

docs/cli.rst

@@ -261,7 +261,7 @@ The ``--nl``, ``--csv``, ``--tsv`` and ``--table`` options are all available.
 Listing views
 =============
 
-The `views` command shows any views defined in the database::
+The ``views`` command shows any views defined in the database::
 
     $ sqlite-utils views sf-trees.db --table --counts --columns --schema
     view         count  columns               schema
@@ -279,6 +279,34 @@ It takes the same options as the ``tables`` command:
 * ``--tsv``
 * ``--table``
 
+.. _cli_triggers:
+
+Listing triggers
+================
+
+The ``triggers`` command shows any triggers configured for the database::
+
+    % sqlite-utils triggers global-power-plants.db --table
+    name             table      sql
+    ---------------  ---------  -----------------------------------------------------------------
+    plants_insert    plants     CREATE TRIGGER [plants_insert] AFTER INSERT ON [plants]
+                                BEGIN
+                                    INSERT OR REPLACE INTO [_counts]
+                                    VALUES (
+                                      'plants',
+                                      COALESCE(
+                                        (SELECT count FROM [_counts] WHERE [table] = 'plants'),
+                                      0
+                                      ) + 1
+                                    );
+                                END
+
+It defaults to showing triggers for all tables. To see triggers for one or more specific tables pass their names as arguments::
+
+    % sqlite-utils triggers global-power-plants.db plants
+
+The command takes the same format options as the ``tables`` and ``views`` commands.
+
 .. _cli_analyze_tables:
 
 Analyzing tables

sqlite_utils/cli.py

@@ -1100,6 +1100,53 @@ def rows(
     )
 
 
+@cli.command()
+@click.argument(
+    "path",
+    type=click.Path(file_okay=True, dir_okay=False, allow_dash=False),
+    required=True,
+)
+@click.argument("tables", nargs=-1)
+@output_options
+@load_extension_option
+@click.pass_context
+def triggers(
+    ctx,
+    path,
+    tables,
+    nl,
+    arrays,
+    csv,
+    tsv,
+    no_headers,
+    table,
+    fmt,
+    json_cols,
+    load_extension,
+):
+    "Show triggers configured in this database"
+    sql = "select name, tbl_name as [table], sql from sqlite_master where type = 'trigger'"
+    if tables:
+        quote = sqlite_utils.Database(memory=True).escape
+        sql += " and [table] in ({})".format(
+            ", ".join(quote(table) for table in tables)
+        )
+    ctx.invoke(
+        query,
+        path=path,
+        sql=sql,
+        nl=nl,
+        arrays=arrays,
+        csv=csv,
+        tsv=tsv,
+        no_headers=no_headers,
+        table=table,
+        fmt=fmt,
+        json_cols=json_cols,
+        load_extension=load_extension,
+    )
+
+
 @cli.command()
 @click.argument(
     "path",

tests/test_cli.py

@@ -5,6 +5,7 @@ import json
 import os
 import pytest
 from sqlite_utils.utils import sqlite3, find_spatialite
+import textwrap
 
 from .utils import collapse_whitespace
 
@@ -1736,3 +1737,40 @@ def test_search(tmpdir, fts, extra_arg, expected):
     )
     assert result.exit_code == 0
     assert result.output == expected
+
+
+_TRIGGERS_EXPECTED = '[{"name": "blah", "table": "articles", "sql": "CREATE TRIGGER blah AFTER INSERT ON articles\\nBEGIN\\n    UPDATE counter SET count = count + 1;\\nEND"}]\n'
+
+
+@pytest.mark.parametrize(
+    "extra_args,expected",
+    [([], _TRIGGERS_EXPECTED), (["articles"], _TRIGGERS_EXPECTED), (["counter"], "")],
+)
+def test_triggers(tmpdir, extra_args, expected):
+    db_path = str(tmpdir / "test.db")
+    db = Database(db_path)
+    db["articles"].insert(
+        {"id": 1, "title": "Title the first"},
+        pk="id",
+    )
+    db["counter"].insert({"count": 1})
+    db.conn.execute(
+        textwrap.dedent(
+            """
+        CREATE TRIGGER blah AFTER INSERT ON articles
+        BEGIN
+            UPDATE counter SET count = count + 1;
+        END
+    """
+        )
+    )
+    args = ["triggers", db_path]
+    if extra_args:
+        args.extend(extra_args)
+    result = CliRunner().invoke(
+        cli.cli,
+        args,
+        catch_exceptions=False,
+    )
+    assert result.exit_code == 0
+    assert result.output == expected