implemented Statement#toString()

src/objects/statement.cpp

@@ -71,6 +71,7 @@ INIT(Statement::Init) {
 		PrototypeMethod<Statement, &Statement::JS_raw>("raw", addon),
 		PrototypeMethod<Statement, &Statement::JS_safeIntegers>("safeIntegers", addon),
 		PrototypeMethod<Statement, &Statement::JS_columns>("columns", addon),
+		PrototypeMethod<Statement, &Statement::JS_toString>("toString", addon),
 	}, addon);
 }
 
@@ -353,6 +354,22 @@ NODE_METHOD(Statement::JS_columns) {
 	return columns;
 }
 
+NODE_METHOD(Statement::JS_toString) {
+	Statement* stmt = ::Unwrap<Statement>(info.This());
+	Addon* addon = stmt->db->GetAddon();
+
+	char* expanded = stmt->alive && stmt->bound ? sqlite3_expanded_sql(stmt->handle) : NULL;
+	if (expanded != NULL) {
+		Napi::Value ret = StringFromUtf8(info.Env(), expanded, -1);
+		sqlite3_free(expanded);
+		return ret;
+	}
+
+	return info.This().As<Napi::Object>()
+		.Get(addon->cs.source.Value())
+		.As<Napi::String>();
+}
+
 NODE_GETTER(Statement::JS_busy) {
 	Statement* stmt = ::Unwrap<Statement>(info.This());
 	return Napi::Boolean::New(info.Env(), stmt->alive && stmt->locked);

src/objects/statement.hpp

@@ -49,6 +49,7 @@ private:
 	static NODE_METHOD(JS_raw);
 	static NODE_METHOD(JS_safeIntegers);
 	static NODE_METHOD(JS_columns);
+	static NODE_METHOD(JS_toString);
 	static NODE_GETTER(JS_busy);
 
 	Database* db;

test/26.statement.to-string.js

@@ -0,0 +1,69 @@
+'use strict';
+const Database = require('../.');
+
+describe('Statement#toString()', function () {
+	beforeEach(function () {
+		this.db = new Database(util.next());
+		this.db.prepare('CREATE TABLE entries (a TEXT, b INTEGER, c BLOB)').run();
+	});
+	afterEach(function () {
+		this.db.close();
+	});
+
+	it('should return the source SQL for a statement with no parameters', function () {
+		const source = 'SELECT * FROM entries';
+		const stmt = this.db.prepare(source);
+		expect(stmt.toString()).to.equal(source);
+		expect(stmt.toString()).to.equal(stmt.source);
+	});
+	it('should return the source SQL when parameters have not been bound', function () {
+		const source = 'SELECT * FROM entries WHERE a = ? AND b = ?';
+		const stmt = this.db.prepare(source);
+		expect(stmt.toString()).to.equal(source);
+		expect(stmt.toString()).to.equal(stmt.source);
+	});
+	it('should not use temporary parameters passed to execution methods', function () {
+		this.db.exec("INSERT INTO entries (a, b) VALUES ('foobar', 1), ('foobar', 2)");
+		const source = 'SELECT b FROM entries WHERE a = ?';
+		const stmt = this.db.prepare(source);
+		const yielded = [];
+		for (const { b } of stmt.iterate('foobar')) {
+			yielded.push(b);
+			expect(stmt.toString()).to.equal(source);
+		}
+		expect(stmt.toString()).to.equal(source);
+		expect(yielded).to.deep.equal([1, 2]);
+	});
+	it('should return the expanded SQL after parameters are bound', function () {
+		const stmt = this.db.prepare('SELECT * FROM entries WHERE a = ? AND b = ?');
+		stmt.bind('foo', 25);
+		expect(stmt.toString()).to.equal("SELECT * FROM entries WHERE a = 'foo' AND b = 25.0");
+	});
+	it('should expand NULL and blob parameters', function () {
+		const stmt = this.db.prepare('INSERT INTO entries VALUES (?, ?, ?)');
+		stmt.bind(null, 25, Buffer.from([0xde, 0xad]));
+		expect(stmt.toString()).to.equal("INSERT INTO entries VALUES (NULL, 25.0, x'dead')");
+	});
+	it('should return the source SQL when bound with no parameters', function () {
+		const source = 'SELECT 555';
+		const stmt = this.db.prepare(source);
+		stmt.bind();
+		expect(stmt.toString()).to.equal(source);
+	});
+	it('should return the source SQL after the database is closed', function () {
+		const source = 'SELECT * FROM entries WHERE a = ?';
+		const stmt = this.db.prepare(source);
+		stmt.bind('foobar');
+		expect(stmt.toString()).to.equal("SELECT * FROM entries WHERE a = 'foobar'");
+		this.db.close();
+		expect(stmt.toString()).to.equal(source);
+		expect(stmt.toString()).to.equal(stmt.source);
+	});
+	it('should be used when coercing a statement to a string', function () {
+		const stmt = this.db.prepare('SELECT * FROM entries WHERE a = ? AND b = ?');
+		expect(String(stmt)).to.equal('SELECT * FROM entries WHERE a = ? AND b = ?');
+		expect(`${stmt}`).to.equal('SELECT * FROM entries WHERE a = ? AND b = ?');
+		stmt.bind('foo', 25);
+		expect('' + stmt).to.equal("SELECT * FROM entries WHERE a = 'foo' AND b = 25.0");
+	});
+});