cube-error

This library adds some standardization to errors, and provides an easy way of building new error types.

Installation

npm install cube-error --save

Usage

It is simple to require in the library and throw a standardized error:

var CustomErrors = require("cube-error");

throw new CustomErrors.NotFound("Hello");

The real power, however, comes with matching an error-type:

somethingThatFails(function(error) {
  if(error && error.is(CustomErrors.NotFound)) {
    //do something
    return;
  }
  if(error) {
    //do else
    return;
  }
  //success
});

Supported errors

We currently support these errors:

• NotFound(message, previousError): Used when a resource could not be located.
• HttpError(statusCode, message, previousError): Maps common status codes to correct errors. 404 maps to NotFound. Otherwise returns a HttpError with a statusCode field.
• Conflict(message, previousError): Used when a resource modification conflicts with existing internal state.
• MissingArgument(message, previousError): Can be used when arguments were expected but not passed.
• InvalidArgument(invalidArgumentName, message, previousError): Can be used as a custom TypeError to indicate unexpected input-type or value The error has a invalidArgument-field which stores the value of invalidArgumentName
• Unauthorized(message, previousError): Can be used to indicate that authorization has failed. A message can be included to provide a reason as to what will happen as a consequence.
• Internal(message, previousError): Used when an error happens, which can't be recognized as any other error type.

Custom should never be instantiated, but is intended to be inherited from.

Building custom errors

You can build a custom error by inheriting from Custom:

var CustomError = require("cube-error").Custom;

function MyError(message, previousError) {
  CustomError.call(this, message, previousError);
  //something custom?
}
util.inherits(MyError, CustomError);

This error will come prepackaged with is(MyError), stack, message, and previousError fields.

TODO

• Map HttpError to more errors in specific cases. Some ideas are:
  • 400 to BadRequestError
  • 403 to ForbiddenError
  • 500 to InternalServerError
• Make HttpError alternate classes always have a statusCode anyway (to reduce breakingness of changes when introducing new mappings).
• Test CustomError extension as a thing in unit tests.
• Handle the case where CustomError is subclasses wrongly (eg. var MyError = function() {}; util.inherits(MyError, CustomError);), and no this.constructor.name exists.