CODEWITHSUNDEEP
javascripttypescript
Ole
Ole

Reputation: 47058

Accessing configuration default values in Typescript?

I'm wondering if there is a more efficient / more compact way to do this. I have a configuration class instance where all the state is optional. It looks like this. I have a constructor like this (StoreConfig is pasted below):

constructor(config?:StoreConfig) {
    config = config ? config : new StoreConfig();

}

Now just use the config with the default value getters.

/**
 * Store configuration.
 */
export class StoreConfig {
  static ID_KEY_DEFAULT:string = 'id';
  static GUID_KEY_DEFAULT:string = 'gid';

  constructor(private _idKey?:string, private _guidKey?:string) {};

  get idKey():string {
    return  this._idKey ? this._idKey : StoreConfig.ID_KEY_DEFAULT;
  }
  get guidKey():string {
    return this.guidKey ? this.guidKey : StoreConfig.GUID_KEY_DEFAULT;
  }
}

Upvotes: 0

Views: 523

Answers (2)

Ole
Ole

Reputation: 47058

This ended up working pretty well for the general design I was going for:

export const STORE_CONFIG_DEFAULT: StoreConfig = {
  idKey: "id",
  guidKey: "gid"
};

Object.freeze(STORE_CONFIG_DEFAULT);

export class StoreConfig {
  public idKey: string;
  public guidKey: string;
  constructor(c?: Partial<StoreConfig>) {
    let config = Object.assign({ ...STORE_CONFIG_DEFAULT }, c);
    this.idKey = config.idKey;
    this.guidKey = config.guidKey;
  }
}

Some other classes can now rely on STORE_CONFIG_DEFAULT for the default configuration.

Upvotes: 0

Uzi
Uzi

Reputation: 2634

Use a default value for your constructor arguments, like so:

export class StoreConfig {
  constructor(
    private _idKey: string = "id",
    private _guidKey: string = "gid"
  ) {}

  get idKey(): string {
    return this._idKey
  }
  get guidKey(): string {
    return this._guidKey
  }
}

by providing a default value you're letting Typescript know this is an optional argument that falls back to its default value.

then it doesn't complain about missing arguments when you do this:

const x = new StoreConfig()

Upvotes: 1

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