lovefield-ts

Lovefield Typescript port and modernization.

The port attempts to maintain API compatibility with original Lovefield. As a result, some parts may conflict with TypeScript best practice (e.g. interface name must start with capital I).

Expectations

Supported

• Most of original Lovefield features (except Firebase and static schema).
• NEW: NodeJS support: NodeJS 10+ will be supported (with memory store only).

Unsupported

• Legacy browsers and technologies. Please assume ES6 throughout.
  • As of Apr 2020, Chrome 60+, Firefox 60+, Safari 10+, Edge are supported.
  • Currently only continuously tested on latest Chrome given resource shortage.
• Firebase is no longer supported.
  • This project is not sponsored by Google and the developers do not have unlimited access for this project.
  • Firebase API changed and legacy Lovefield code cannot be used.
• Static schema: it was designed for use with Closure compiler. Since the tool chain has moved to TypeScript, it makes no sense to support it.

Dist changes

• Lovefield-ts no longer ships minified JavaScript file. Instead, it provides
  • A concatenated TypeScript file that you can directly include in your TypeScript project and compile to any module system you would like to use.
  • Pre-compiled ES5/ES6 modules with source map and TypeScript declarations. Just import it and use your existing packing/minifying config.
• Lovefield-ts no longer uses flags to do compile-time control. Instead, a runtime options object will be used. The interface is defined in lib/base/lovefield_options.ts. Users are supposed to define an object following that interface and set options via the new API lf.options.set().
  • By default, an options object not providing error message explanations is provided for better minify performance. If you wish to include detailed error message in your package, use or copy testing/debug_options.ts.

API changes

• All namespaces are flattened. For example:

  • lf.Order is flattened to Order
  • lf.schema.DataStoreType is flattened to DataStoreType

  Please note, in ES6 modules, we usually do

  import * as lf from './node_modules/lovefield-ts/dist/es6/lf.js';
  const order = lf.Order.DESC;  // still prefixed by lf, ES6 module syntax

• TypeScript users cannot refer column by name, use .col() API.

  const item = db.getSchema().table('Item');
  
  // Use .col() API to refer to column here.
  // TypeScript indexed property forces everything to be typed the same.
  // This is a language limit and not much Lovefield authors can do here.
  //
  // item['orderDate']  <== this will cause type errors
  // item.col('orderDate')  <== this will give perfect type checking
  return db.select().from(item).orderBy(item.col('orderDate')).exec();

Test changes

• API tester and performance benchmarks are not implemented yet. They will be implemented in JavaScript but remove dependencies on Closure Libraries completely.

Building and development instructions

The project is set to use modern Typescript (3.8+) and Mocha/Chai/Sinon/Karma as its test framework. Compilation/test speed has improved significantly.

Development set up

• Install Chrome
• Install Node 12+
• npm install
• node node_modules/guppy-cli/bin/index.js pre-commit

Lovefield-ts uses gulp 4, which is incompatible with gulp 3 that original Lovefield uses. If you had installed gulp globally as suggested in README of Lovefield, please run:

npm uninstall -g gulp

Development flow

Run gulp to see the commands.

Please note that certain tests are only runnable in Karma (e.g. IndexedDB related tests), and these tests will be named *_spec.ts.

Directory structures

• lib: Lovefield main library source code
• testing: Facility code used for testing
• tests: Tests for Lovefield main library
• out: Temporary directory used to store intermediate files from tool chain
• dist: Generated dist files
• coverage: Code coverage report