Type alias TransformerFunc<T>

Any function conforming to this interface may be passed to the configValue function to transform the value of a given config key.

Example

const myType = ((val: string | undefined, varname: string) => {
  if (!val) {
    if (def === REQUIRED) {
      return `::ERROR::${varname}::This value is required`;
    }
    return def;
  }
  try {
    // Normally you would validate but for testing we're skipping that and just returning whatever
    return JSON.parse(val) as MyType;
  } catch (e: any) {
    return `::ERROR::${varname}::Invalid JSON string passed: ${e.message}`;
  }
}) as TransformerFunction<MyType>;

// ...

const configDef = {
  myType: configValue('MY_TYPE', myType, REQUIRED),
  // ...
}
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