From e8b898af6341bdb6e2838c505711caeba384e99b Mon Sep 17 00:00:00 2001
From: Richard Wheeler <Richard_Wheeler@rjew.info>
Date: Mon, 30 Mar 2026 16:59:04 -0400
Subject: [PATCH] db.sqlite: add tables, columns, schema, db_size methods
 (#26791)

* db.sqlite: add tables, columns, schema, and db_size convenience methods

Add four methods to sqlite.DB for common introspection queries:
- tables() returns all user table names
- columns(table) returns column names for a table
- schema(table) returns CREATE statements
- db_size() returns database file size via page_count * page_size

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* db.sqlite: escape table names in columns() and schema()

Quote table names with double-quote escaping in columns() PRAGMA
and single-quote escaping in schema() filter to handle table names
containing spaces, punctuation, or quotes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Richard Wheeler <gumpy@Richards-MacBook-Pro.local>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
---
 vlib/db/sqlite/sqlite.c.v    | 37 ++++++++++++++++++++++++++++++++
 vlib/db/sqlite/sqlite_test.v | 41 ++++++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/vlib/db/sqlite/sqlite.c.v b/vlib/db/sqlite/sqlite.c.v
index 0946a2da8..5d792c577 100644
--- a/vlib/db/sqlite/sqlite.c.v
+++ b/vlib/db/sqlite/sqlite.c.v
@@ -582,6 +582,43 @@ pub fn (mut db DB) release_savepoint(savepoint string) ! {
 	db.exec('RELEASE SAVEPOINT ${savepoint};')!
 }
 
+// tables returns the names of all user tables in the database.
+pub fn (db &DB) tables() ![]string {
+	rows := db.exec("SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%' ORDER BY name")!
+	return rows.map(it.vals[0])
+}
+
+// columns returns the column names for the given table.
+pub fn (db &DB) columns(table string) ![]string {
+	escaped := table.replace('"', '""')
+	rows := db.exec('PRAGMA table_info("${escaped}")')!
+	return rows.map(it.vals[1])
+}
+
+// schema returns the CREATE statement(s) for the given table, or for all
+// objects if table is empty.
+pub fn (db &DB) schema(table string) !string {
+	filter := if table != '' {
+		escaped := table.replace("'", "''")
+		"AND name='${escaped}'"
+	} else {
+		''
+	}
+	rows := db.exec("SELECT sql FROM sqlite_master WHERE type IN ('table','index','view','trigger') ${filter} AND sql IS NOT NULL ORDER BY type, name")!
+	return rows.map(it.vals[0]).join('\n\n')
+}
+
+// db_size returns the database file size in bytes, computed from page_count
+// and page_size.
+pub fn (db &DB) db_size() !i64 {
+	pc := db.exec('PRAGMA page_count')!
+	ps := db.exec('PRAGMA page_size')!
+	if pc.len == 0 || ps.len == 0 {
+		return 0
+	}
+	return pc[0].vals[0].i64() * ps[0].vals[0].i64()
+}
+
 // reset returns the connection to initial state for reuse
 pub fn (mut db DB) reset() ! {
 }
diff --git a/vlib/db/sqlite/sqlite_test.v b/vlib/db/sqlite/sqlite_test.v
index 22fdb9b2d..5e1de389c 100644
--- a/vlib/db/sqlite/sqlite_test.v
+++ b/vlib/db/sqlite/sqlite_test.v
@@ -1,6 +1,7 @@
 // vtest build: present_sqlite3?
 import db.sqlite
 import orm
+import os
 
 type Connection = sqlite.DB
 
@@ -148,6 +149,46 @@ fn test_exec_param_many2() {
 	db.close()!
 }
 
+fn test_tables() {
+	mut db := sqlite.connect(':memory:') or { panic(err) }
+	db.exec('create table alpha (id integer)')!
+	db.exec('create table beta (id integer)')!
+	tbl := db.tables()!
+	assert tbl == ['alpha', 'beta']
+	db.close()!
+}
+
+fn test_columns() {
+	mut db := sqlite.connect(':memory:') or { panic(err) }
+	db.exec('create table items (id integer primary key, name text, price real)')!
+	cols := db.columns('items')!
+	assert cols == ['id', 'name', 'price']
+	db.close()!
+}
+
+fn test_schema() {
+	mut db := sqlite.connect(':memory:') or { panic(err) }
+	db.exec('create table things (id integer primary key, label text)')!
+	s := db.schema('things')!
+	assert s.contains('CREATE TABLE things')
+	// empty table name returns all objects
+	all := db.schema('')!
+	assert all.contains('CREATE TABLE things')
+	db.close()!
+}
+
+fn test_db_size() {
+	tmp := os.join_path(os.temp_dir(), 'test_db_size.db')
+	defer {
+		os.rm(tmp) or {}
+	}
+	mut db := sqlite.connect(tmp) or { panic(err) }
+	db.exec('create table t (id integer)')!
+	sz := db.db_size()!
+	assert sz > 0
+	db.close()!
+}
+
 fn test_orm_transaction_interface() {
 	mut db := sqlite.connect(':memory:') or { panic(err) }
 	defer {
-- 
2.39.5