Configr is a library that provides a set of TypeScript decorators to inject configuration params into class properties.
npm install @6river/configrtypescript
// Given is expected configuration received from some remote service or
// is read from the file or....
const config = {
env: 'debug',
log: {
level: 'DEBUG',
format: '%h %l %u %t \"%r\" %>s %b'
}
};// Basic Usage
@Config()
class Foo {
@ConfigParam()
readonly env: string;
// by default property name is used as a path to access config parameter,
// but path can elso be specified:
@ConfigParam('log.level')
readonly logLevel: string;
// with default specified
@ConfigParam('log.format')
readonly logFormat: string = ''%h %l %u';
}
// The root path can be specified on class level
@Config({root: 'log'})
class Logger {
@ConfigParam()
level string;
@ConfigParam()
format string;
}
// suppose we have configuration fetched from remote service
function loadConfig() {
return fetch('http://example.com/config.json')
.then(function(response) {
return response.json();
})
.then(function(cfg) {
// Apply loaded config to annotated properties.
// This method should be calledonce.
// It's not forbidden to call it many times but
// all subsequent calls just have no effect.
return configResolve(cfg);
});
}
// as soon as config is loaded and resolved it's safe to use
// our objects that rely on its parameters:
async function useit() {
await loadConfig(cfg);
const foo = new Foo();
const log = new Logger();
}
`Advanced Usage
$3
Parser can be specified as an additional option for decorator:`typescript
const cfg = {
logLevels: ['ERROR', 'INFO', 'DEBUG']
};class LogLevel {
constructor(public label: string) {}
}
function parseLogLevels(levels: string[]): LogLevel[] {
return labels.map((level) => new LogLevel(level));
}
@Config()
class Foo {
@ConfigParam({parser: parseLogLevels})
readonly logLevels: LogLevel[];
}
``