sqlite: add StatementSync.prototype.columns()

deps/sqlite/sqlite.gyp

@@ -14,6 +14,7 @@
       },
       'defines': [
         'SQLITE_DEFAULT_MEMSTATUS=0',
+        'SQLITE_ENABLE_COLUMN_METADATA',
         'SQLITE_ENABLE_MATH_FUNCTIONS',
         'SQLITE_ENABLE_SESSION',
         'SQLITE_ENABLE_PREUPDATE_HOOK'

deps/sqlite/unofficial.gni

@@ -8,6 +8,7 @@ template("sqlite_gn_build") {
   config("sqlite_config") {
     include_dirs = [ "." ]
     defines = [
+      "SQLITE_ENABLE_COLUMN_METADATA",
       "SQLITE_ENABLE_MATH_FUNCTIONS",
       "SQLITE_ENABLE_SESSION",
       "SQLITE_ENABLE_PREUPDATE_HOOK",

doc/api/sqlite.md

@@ -373,6 +373,34 @@ objects. If the prepared statement does not return any results, this method
 returns an empty array. The prepared statement [parameters are bound][] using
 the values in `namedParameters` and `anonymousParameters`.
 
+### `statement.columns()`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns: {Array} An array of objects. Each object corresponds to a column
+  in the prepared statement, and contains the following properties:
+
+  * `column`: {string|null} The unaliased name of the column in the origin
+    table, or `null` if the column is the result of an expression or subquery.
+    This property is the result of [`sqlite3_column_origin_name()`][].
+  * `database`: {string|null} The unaliased name of the origin database, or
+    `null` if the column is the result of an expression or subquery. This
+    property is the result of [`sqlite3_column_database_name()`][].
+  * `name`: {string} The name assigned to the column in the result set of a
+    `SELECT` statement. This property is the result of
+    [`sqlite3_column_name()`][].
+  * `table`: {string|null} The unaliased name of the origin table, or `null` if
+    the column is the result of an expression or subquery. This property is the
+    result of [`sqlite3_column_table_name()`][].
+  * `type`: {string|null} The declared data type of the column, or `null` if the
+    column is the result of an expression or subquery. This property is the
+    result of [`sqlite3_column_decltype()`][].
+
+This method is used to retrieve information about the columns returned by the
+prepared statement.
+
 ### `statement.expandedSQL`
 
 <!-- YAML
@@ -687,6 +715,11 @@ resolution handler passed to [`database.applyChangeset()`][]. See also
 [`sqlite3_backup_step()`]: https://www.sqlite.org/c3ref/backup_finish.html#sqlite3backupstep
 [`sqlite3_changes64()`]: https://www.sqlite.org/c3ref/changes.html
 [`sqlite3_close_v2()`]: https://www.sqlite.org/c3ref/close.html
+[`sqlite3_column_database_name()`]: https://www.sqlite.org/c3ref/column_database_name.html
+[`sqlite3_column_decltype()`]: https://www.sqlite.org/c3ref/column_decltype.html
+[`sqlite3_column_name()`]: https://www.sqlite.org/c3ref/column_name.html
+[`sqlite3_column_origin_name()`]: https://www.sqlite.org/c3ref/column_database_name.html
+[`sqlite3_column_table_name()`]: https://www.sqlite.org/c3ref/column_database_name.html
 [`sqlite3_create_function_v2()`]: https://www.sqlite.org/c3ref/create_function.html
 [`sqlite3_exec()`]: https://www.sqlite.org/c3ref/exec.html
 [`sqlite3_expanded_sql()`]: https://www.sqlite.org/c3ref/expanded_sql.html

src/env_properties.h

@@ -118,6 +118,7 @@
   V(crypto_rsa_pss_string, "rsa-pss")                                          \
   V(cwd_string, "cwd")                                                         \
   V(data_string, "data")                                                       \
+  V(database_string, "database")                                               \
   V(default_is_true_string, "defaultIsTrue")                                   \
   V(deserialize_info_string, "deserializeInfo")                                \
   V(dest_string, "dest")                                                       \
@@ -370,6 +371,7 @@
   V(subject_string, "subject")                                                 \
   V(subjectaltname_string, "subjectaltname")                                   \
   V(syscall_string, "syscall")                                                 \
+  V(table_string, "table")                                                     \
   V(target_string, "target")                                                   \
   V(thread_id_string, "threadId")                                              \
   V(ticketkeycallback_string, "onticketkeycallback")                           \

src/node_sqlite.cc

@@ -158,6 +158,16 @@ inline void THROW_ERR_SQLITE_ERROR(Isolate* isolate, int errcode) {
   }
 }
 
+inline MaybeLocal<Value> NullableSQLiteStringToValue(Isolate* isolate,
+                                                     const char* str) {
+  if (str == nullptr) {
+    return Null(isolate);
+  }
+
+  return String::NewFromUtf8(isolate, str, NewStringType::kInternalized)
+      .As<Value>();
+}
+
 class BackupJob : public ThreadPoolWork {
  public:
   explicit BackupJob(Environment* env,
@@ -1897,6 +1907,72 @@ void StatementSync::Run(const FunctionCallbackInfo<Value>& args) {
   args.GetReturnValue().Set(result);
 }
 
+void StatementSync::Columns(const FunctionCallbackInfo<Value>& args) {
+  StatementSync* stmt;
+  ASSIGN_OR_RETURN_UNWRAP(&stmt, args.This());
+  Environment* env = Environment::GetCurrent(args);
+  THROW_AND_RETURN_ON_BAD_STATE(
+      env, stmt->IsFinalized(), "statement has been finalized");
+  int num_cols = sqlite3_column_count(stmt->statement_);
+  Isolate* isolate = env->isolate();
+  LocalVector<Value> cols(isolate);
+  LocalVector<Name> col_keys(isolate,
+                             {env->column_string(),
+                              env->database_string(),
+                              env->name_string(),
+                              env->table_string(),
+                              env->type_string()});
+  Local<Value> value;
+
+  cols.reserve(num_cols);
+  for (int i = 0; i < num_cols; ++i) {
+    LocalVector<Value> col_values(isolate);
+    col_values.reserve(col_keys.size());
+
+    if (!NullableSQLiteStringToValue(
+             isolate, sqlite3_column_origin_name(stmt->statement_, i))
+             .ToLocal(&value)) {
+      return;
+    }
+    col_values.emplace_back(value);
+
+    if (!NullableSQLiteStringToValue(
+             isolate, sqlite3_column_database_name(stmt->statement_, i))
+             .ToLocal(&value)) {
+      return;
+    }
+    col_values.emplace_back(value);
+
+    if (!stmt->ColumnNameToName(i).ToLocal(&value)) {
+      return;
+    }
+    col_values.emplace_back(value);
+
+    if (!NullableSQLiteStringToValue(
+             isolate, sqlite3_column_table_name(stmt->statement_, i))
+             .ToLocal(&value)) {
+      return;
+    }
+    col_values.emplace_back(value);
+
+    if (!NullableSQLiteStringToValue(
+             isolate, sqlite3_column_decltype(stmt->statement_, i))
+             .ToLocal(&value)) {
+      return;
+    }
+    col_values.emplace_back(value);
+
+    Local<Object> column = Object::New(isolate,
+                                       Null(isolate),
+                                       col_keys.data(),
+                                       col_values.data(),
+                                       col_keys.size());
+    cols.emplace_back(column);
+  }
+
+  args.GetReturnValue().Set(Array::New(isolate, cols.data(), cols.size()));
+}
+
 void StatementSync::SourceSQLGetter(const FunctionCallbackInfo<Value>& args) {
   StatementSync* stmt;
   ASSIGN_OR_RETURN_UNWRAP(&stmt, args.This());
@@ -2002,6 +2078,8 @@ Local<FunctionTemplate> StatementSync::GetConstructorTemplate(
     SetProtoMethod(isolate, tmpl, "all", StatementSync::All);
     SetProtoMethod(isolate, tmpl, "get", StatementSync::Get);
     SetProtoMethod(isolate, tmpl, "run", StatementSync::Run);
+    SetProtoMethodNoSideEffect(
+        isolate, tmpl, "columns", StatementSync::Columns);
     SetSideEffectFreeGetter(isolate,
                             tmpl,
                             FIXED_ONE_BYTE_STRING(isolate, "sourceSQL"),

src/node_sqlite.h

@@ -116,6 +116,7 @@ class StatementSync : public BaseObject {
   static void Iterate(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Get(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Run(const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void Columns(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void SourceSQLGetter(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void ExpandedSQLGetter(
       const v8::FunctionCallbackInfo<v8::Value>& args);

test/parallel/test-sqlite-statement-sync-columns.js

@@ -0,0 +1,161 @@
+'use strict';
+require('../common');
+const assert = require('node:assert');
+const { DatabaseSync } = require('node:sqlite');
+const { suite, test } = require('node:test');
+
+suite('StatementSync.prototype.columns()', () => {
+  test('returns column metadata for core SQLite types', () => {
+    const db = new DatabaseSync(':memory:');
+    db.exec(`CREATE TABLE test (
+      col1 INTEGER,
+      col2 REAL,
+      col3 TEXT,
+      col4 BLOB,
+      col5 NULL
+    )`);
+    const stmt = db.prepare('SELECT col1, col2, col3, col4, col5 FROM test');
+    assert.deepStrictEqual(stmt.columns(), [
+      {
+        __proto__: null,
+        column: 'col1',
+        database: 'main',
+        name: 'col1',
+        table: 'test',
+        type: 'INTEGER',
+      },
+      {
+        __proto__: null,
+        column: 'col2',
+        database: 'main',
+        name: 'col2',
+        table: 'test',
+        type: 'REAL',
+      },
+      {
+        __proto__: null,
+        column: 'col3',
+        database: 'main',
+        name: 'col3',
+        table: 'test',
+        type: 'TEXT',
+      },
+      {
+        __proto__: null,
+        column: 'col4',
+        database: 'main',
+        name: 'col4',
+        table: 'test',
+        type: 'BLOB',
+      },
+      {
+        __proto__: null,
+        column: 'col5',
+        database: 'main',
+        name: 'col5',
+        table: 'test',
+        type: null,
+      },
+    ]);
+  });
+
+  test('supports statements using multiple tables', () => {
+    const db = new DatabaseSync(':memory:');
+    db.exec(`
+      CREATE TABLE test1 (value1 INTEGER);
+      CREATE TABLE test2 (value2 INTEGER);
+    `);
+    const stmt = db.prepare('SELECT value1, value2 FROM test1, test2');
+    assert.deepStrictEqual(stmt.columns(), [
+      {
+        __proto__: null,
+        column: 'value1',
+        database: 'main',
+        name: 'value1',
+        table: 'test1',
+        type: 'INTEGER',
+      },
+      {
+        __proto__: null,
+        column: 'value2',
+        database: 'main',
+        name: 'value2',
+        table: 'test2',
+        type: 'INTEGER',
+      },
+    ]);
+  });
+
+  test('supports column aliases', () => {
+    const db = new DatabaseSync(':memory:');
+    db.exec(`CREATE TABLE test (value INTEGER)`);
+    const stmt = db.prepare('SELECT value AS foo FROM test');
+    assert.deepStrictEqual(stmt.columns(), [
+      {
+        __proto__: null,
+        column: 'value',
+        database: 'main',
+        name: 'foo',
+        table: 'test',
+        type: 'INTEGER',
+      },
+    ]);
+  });
+
+  test('supports column expressions', () => {
+    const db = new DatabaseSync(':memory:');
+    db.exec(`CREATE TABLE test (value INTEGER)`);
+    const stmt = db.prepare('SELECT value + 1, value FROM test');
+    assert.deepStrictEqual(stmt.columns(), [
+      {
+        __proto__: null,
+        column: null,
+        database: null,
+        name: 'value + 1',
+        table: null,
+        type: null,
+      },
+      {
+        __proto__: null,
+        column: 'value',
+        database: 'main',
+        name: 'value',
+        table: 'test',
+        type: 'INTEGER',
+      },
+    ]);
+  });
+
+  test('supports subqueries', () => {
+    const db = new DatabaseSync(':memory:');
+    db.exec(`CREATE TABLE test (value INTEGER)`);
+    const stmt = db.prepare('SELECT * FROM (SELECT * FROM test)');
+    assert.deepStrictEqual(stmt.columns(), [
+      {
+        __proto__: null,
+        column: 'value',
+        database: 'main',
+        name: 'value',
+        table: 'test',
+        type: 'INTEGER',
+      },
+    ]);
+  });
+
+  test('supports statements that do not return data', () => {
+    const db = new DatabaseSync(':memory:');
+    db.exec('CREATE TABLE test (value INTEGER)');
+    const stmt = db.prepare('INSERT INTO test (value) VALUES (?)');
+    assert.deepStrictEqual(stmt.columns(), []);
+  });
+
+  test('throws if the statement is finalized', () => {
+    const db = new DatabaseSync(':memory:');
+    db.exec('CREATE TABLE test (value INTEGER)');
+    const stmt = db.prepare('SELECT value FROM test');
+    db.close();
+    assert.throws(() => {
+      stmt.columns();
+    }, /statement has been finalized/);
+  });
+});