Add option to set the default transaction behavior

Fixes WiseLibs#1217

docs/api.md

@@ -35,6 +35,8 @@ Various options are accepted:
 
 - `options.timeout`: the number of milliseconds to wait when executing queries on a locked database, before throwing a `SQLITE_BUSY` error (default: `5000`).
 
+- `options.defaultTransactionBehaviour`: Set the default transaction behavior when calling [Database#transaction()](#transactionfunction---function). Can be set as `null` (SQLite Default), `'deferred'`, `'immediate'` or `'exclusive'` (default: `null`).
+
 - `options.verbose`: provide a function that gets called with every SQL string executed by the database connection (default: `null`).
 
 - `options.nativeBinding`: if you're using a complicated build system that moves, transforms, or concatenates your JS files, `better-sqlite3` might have trouble locating its native C++ addon (`better_sqlite3.node`). If you get an error that looks like [this](https://github.com/JoshuaWise/better-sqlite3/issues/534#issuecomment-757907190), you can solve it by using this option to provide the file path of `better_sqlite3.node` (relative to the current working directory).
@@ -86,7 +88,8 @@ const adopt = db.transaction((cats) => {
 Transactions also come with `deferred`, `immediate`, and `exclusive` versions.
 
 ```js
-insertMany(cats); // uses "BEGIN"
+insertMany(cats) // uses the default set by options.defaultTransactionBehavior
+insertMany.default(cats); // uses "BEGIN"
 insertMany.deferred(cats); // uses "BEGIN DEFERRED"
 insertMany.immediate(cats); // uses "BEGIN IMMEDIATE"
 insertMany.exclusive(cats); // uses "BEGIN EXCLUSIVE"

lib/database.js

@@ -34,13 +34,18 @@ function Database(filenameGiven, options) {
 	const timeout = 'timeout' in options ? options.timeout : 5000;
 	const verbose = 'verbose' in options ? options.verbose : null;
 	const nativeBinding = 'nativeBinding' in options ? options.nativeBinding : null;
+	const defaultTransactionBehavior = 'defaultTransactionBehavior' in options ? options.defaultTransactionBehavior : null;
 
 	// Validate interpreted options
 	if (readonly && anonymous && !buffer) throw new TypeError('In-memory/temporary databases cannot be readonly');
 	if (!Number.isInteger(timeout) || timeout < 0) throw new TypeError('Expected the "timeout" option to be a positive integer');
 	if (timeout > 0x7fffffff) throw new RangeError('Option "timeout" cannot be greater than 2147483647');
 	if (verbose != null && typeof verbose !== 'function') throw new TypeError('Expected the "verbose" option to be a function');
 	if (nativeBinding != null && typeof nativeBinding !== 'string' && typeof nativeBinding !== 'object') throw new TypeError('Expected the "nativeBinding" option to be a string or addon object');
+	if (defaultTransactionBehavior != null) {
+		if (typeof defaultTransactionBehavior !== 'string') throw new TypeError('Expected the "defaultTransactionBehavior" option to be a string, expected "deferred", "immediate", or "exclusive"')
+		if (!["deferred", "immediate", "exclusive"].includes(defaultTransactionBehavior)) throw new Error('Invalid value for "defaultTransactionBehavior", expected "deferred", "immediate", or "exclusive"')
+	}
 
 	// Load the native addon
 	let addon;
@@ -66,7 +71,7 @@ function Database(filenameGiven, options) {
 	}
 
 	Object.defineProperties(this, {
-		[util.cppdb]: { value: new addon.Database(filename, filenameGiven, anonymous, readonly, fileMustExist, timeout, verbose || null, buffer || null) },
+		[util.cppdb]: { value: new addon.Database(filename, filenameGiven, anonymous, readonly, fileMustExist, timeout, defaultTransactionBehavior, verbose || null, buffer || null) },
 		...wrappers.getters,
 	});
 }

lib/methods/transaction.js

@@ -11,12 +11,14 @@ module.exports = function transaction(fn) {
 
 	// Each version of the transaction function has these same properties
 	const properties = {
-		default: { value: wrapTransaction(apply, fn, db, controller.default) },
 		deferred: { value: wrapTransaction(apply, fn, db, controller.deferred) },
 		immediate: { value: wrapTransaction(apply, fn, db, controller.immediate) },
 		exclusive: { value: wrapTransaction(apply, fn, db, controller.exclusive) },
 		database: { value: this, enumerable: true },
 	};
+	properties.default = db.defaultTransactionBehavior == null ?
+		{ value: wrapTransaction(apply, fn, db, controller.default) } :
+		properties[db.defaultTransactionBehavior];
 
 	Object.defineProperties(properties.default.value, properties);
 	Object.defineProperties(properties.deferred.value, properties);

lib/methods/wrappers.js

@@ -51,4 +51,8 @@ exports.getters = {
 		get: function memory() { return this[cppdb].memory; },
 		enumerable: true,
 	},
+  defaultTransactionBehavior: {
+    get: function defaultTransactionBehavior() { return this[cppdb].defaultTransactionBehavior; },
+    enumerable: true
+  }
 };