takiwa-error-management v0.2.0

Error Management

Middleware (express)

path: lib/middleware

httpErrorHandler

1. Sends error messages in JSON format from the server to a client
2. Must be configured before use
3. Uses custom templates with placeholders

Usage

const { httpErrorHanlder } = require('error-management');
...
app.use(httpErrorHandler({
  template: {
    error: true,
    message: '%message%'
  }  
}));

Options

examlpe (Single template):

{
  ...
  template: {
    error: true,
    message: '%message%'
  },
  ...
}

When using Multiple templates each one should have required options:

Condition

Defines selection rules for choosing a template

Placeholders

Placeholders are used to define the place for a value taken from the corresponding Error property. For instance, an error like this:

error = new Error('Some error');
error.name = 'ValidationError';

with the template:

{
  template: {
    error: true,
    message: '%message%',
    data: {
      name: '%name%'
    }
  }
}

results in JSON format error message sent to a client:

{
  error: true,
  message: 'Some error',
  data: {
    name: 'ValidationError'
  }
}

Currently supported placeholders:

• %code%
• %extra%
• %message%
• %name%

Configuration examples

example 1: Single template

httpErrorHandler({
  template: {
    error: true,
    message: '%message%'
  }
})

example 2: Multiple templates

httpErrorHandler({
  template: [
    {
      default: true,
      template: {
        status: 'fail',
        data: '%extra%'
      }
    },
    {
      condition: {
        httpStatusCode: 500
      },
      template: {
        status: 'error',
        message: '%message%'
      }
    }
  ]
})

mongooseErrorConverter

1. Checks if passed a mongoose error
2. Extracts mongoose specific data and updates error object properties with it
3. Passes modified error to the next express middleware

Usage

const { mongooseErrorConverter } = require('./errorManagement');
...
app.use(mongooseErrorConverter());

usage with httpErrorHandler:

const { httpErrorHanlder, mongooseErrorConverter } = require('./errorManagement');
...
app.use(mongooseErrorConverter());
app.use(httpErrorHandler({
  template: {
    error: true,
    message: '%message%'
  }  
}));

Supported Mongoose Error Types

Currently supported:

• ValidationError

Helpers

path: lib/helpers

getHTTPStatusCode

Returns http status code corresponding to the given error name.

...
const httpStatusCode = getHTTPStatusCode('ValidationError');

console.log(httpStatusCode); // -> 400

TODO

• add parseMongoose option instead of using mongooseErrorConverter middleware