Safer config access

[LoicPoullain]

Issues

1. Empty config values

In some situations, we may want the Config class to throw an error if a configuration value is not specified. For example, when calling Config.get with "mongodb.uri", we probably want to throw an error if we did not provide the database URI.

2. Strict type checking

The Config.get method coerces the configuration value when possible (for example 'true' becomes true). But it does not guarantee that the type of the configuration value is correct.

For example with the below configuration, Config.get<boolean>('settings.debug') returns a string whereas its TypeScript type is boolean.

settings:
  debug: 'an incorrect value'

Solution

Add two new methods getOrThrow and get2:

// If the config value is true, then return true.
// If the config value is false, then return false.
// If the config value is "true", then return true.
// If the config value is "false", then return false.
// If the config value is "xxx", then throw an error.
// If the config value is not defined, then return the default value (true).
config.get2('settings.foobar', 'boolean', true): boolean;

// Same as above except that if the value is not defined, the method throws an error.
config.getOrThrow('settings.foobar', 'boolean'): boolean;

// Same as above except that if the value is not defined, the method returns undefined.
config.get2('settings.foobar', 'boolean'): boolean | undefined;

// Same with numbers
config.get2('settings.foobar', 'number', 3): number;
config.getOrThrow('settings.foobar', 'number'): number;
config.get2('settings.foobar', 'number'): number | undefined;

// Same with strings
config.get2('settings.foobar', 'string', 'a'): string;
config.getOrThrow('settings.foobar', 'string'): string;
config.get2('settings.foobar', 'string'): string | undefined;

// "Same" with any
config.get2('settings.foobar', 'any', 'a'): any;
config.getOrThrow('settings.foobar', 'any'): any;
config.get2('settings.foobar', 'any'): any;

[LoicPoullain]

Version 1.7 published