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Error response middleware (text, json, html)

JavaScript 62.88% HTML 37.12%

error's Introduction

koa-error

Error response middleware for koa supporting:

text
json
html

Installation

$ npm install koa-error

Options

template path to template written with your template engine, default: ./error.html
engine template engine name passed to consolidate, default: lodash
cache cached compiled functions, default: NODE_ENV != 'development'
env force a NODE_ENV, default: development
accepts mimetypes passed to ctx.accepts, default: [ 'html', 'text', 'json' ]

Custom templates

By using the template option you can override the bland default template, with the following available local variables:

env
ctx
request
response
error
stack
status
code

Here are some examples:

Pug (formerly jade)

app.use(error({
  engine: 'pug',
  template: __dirname + '/error.pug'
}));

doctype html
html
  head
    title= 'Error - ' + status
  body
    #error
      h1 Error
      p Looks like something broke!
      if env == 'development'
        h2 Message:
        pre: code= error
        h2 Stack:
        pre: code= stack

Nunjucks

app.use(error({
  engine: 'nunjucks',
  template: __dirname + '/error.njk'
}));

<!DOCTYPE html>
<html>
  <head>
    <title>Error - {{status}}</title>
  </head>
  <body>
    <div id="error">
      <h1>Error</h1>
    <p>Looks like something broke!</p>
    {% if env == 'development' %}
      <h2>Message:</h2>
      <pre>
        <code>
{{error}}
        </code>
      </pre>
      <h2>Stack:</h2>
      <pre>
        <code>
{{stack}}
        </code>
      </pre>
    {% endif %}
    </div>
  </body>
</html>

License

MIT

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error's Issues

text/html defaults to text

Not sure if this is an error in req.accepts() or koa-errors switch logic.

I was trying to get an html error template working but would only ever get the text error message.
My browsers sending Accepts: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
After debugging this.accepts('text', 'json', 'html') it returns only 'text' so it never gets to the 'html' part of the switch statement. Changing the code to switch(this.accepts('html', 'json', 'text')) {
The html template is used. I'm not sure of the implications of that change as I haven't spent much time trying to figure whats going on ;)
To clarify the change, I switched the 'html' and 'text' values so html is first in the this.accepts() call

Add custom filters and use extend/include the macro/block in view template engine like nunjucks

Use filters & include other tpl code in Nunjucks engine PR36

Directory:

   /
   ├─ app.js
   │
   ├─ filters.js
   │
   └─ tpl
       │
       ├─ com.html
       │
       └─ error.html

tpl/error.html:

<!DOCTYPE html>
<html>
  <head>
    {% include "./com.html" %}
  </head>
  <body>
    <p>{{ request | stringify }}</p> {# use filters here #}
    <!-- ... -->
  </body>
</htm>

tpl/com.html:

<link rel="stylesheet" href="/css/normalize.css" />

filters.js:

module.exports = { 
    // define filters function here
    stringify(..args){
        return JSON.stringify(...args);
    }
    //...
};

app.js:

//...
const nunjucks = require('nunjucks');
const nunjucksEnv = new nunjucks.Environment(
    new nunjucks.FileSystemLoader(path.join(__dirname, 'tpl'))
);
// add filters
const filters = require('./filters');
for(let [k,v] of Object.entries(filters)){
    nunjucksEnv.addFilter(k, v);
}
//...
app.use(koaError({
    //...
    template: path.join(__dirname, 'tpl/error.html'),
    options: {
        nunjucksEnv // custom nunjucks env
    }
}));

See more detail here PR36
more-nunjucks-options

Prevent node's default action when emitting "error"

When an EventEmitter instance experiences an error, the typical action is to emit an 'error' event. Error events are treated as a special case in node. If there is no listener for it, then the default action is to print a stack trace and exit the program.

This is a terrible, terrible default. Right now it's exiting our the program before hitting the switch statement if you don't have your own app level listeners.

stream error

we only do try catch here to catch the error.
but all the streams' and events' errors are handling by stream.on('error', this.onerror), we can do nothing for them, except hack ctx.onerror method.

should we add an easy way for users to write their own error handler in koa, just like what connect/express do:

app.use(function (err, req, res, next){});

or just leave these to error middleware with hack ctx.onerror?

tests

better default template

too lazy right now

Swig is not currently maintained

Per https://github.com/paularmstrong/swig and it currently uses an out of date Uglify.js that has a security vulnerability per nsp

Regular Expression Denial of Service

[email protected] > [email protected]
This is fixed in Uglify > 2.6.9

koa-error doesn't depend on the template engine it uses by default

When the switch was made to consolidate koa-error stopped depending on swig, however the default template is still swig.

This means that unless the parent app either depends on swig or defines its own template and requires a template engine for it; using koa-error will now result in an Error: Cannot find module 'swig' error.

Include a better default templating engine

Per #19 (comment), koa-error is defaulting to a library (Swig) that is no longer maintained, and also is causing nsp to error out due to an out-of-date uglify-js dependency.

Something more current, more widely used, and maintained should be swapped in.

I would suggest one of the following:

ejs
mustachJS
handlebarsJS

Better yet. This could just be done using ES6 JS string templating and remove the dependency all together ;-)

index.js - line 58 - missing comma after 'response: this.response'

There's a missing comma on line 58 of index.js that causes a SyntaxError.

Swig throws in strict mode

$ node --use-strict example.js
/home/parkle/dev/koa-error/node_modules/swig/lib/utils.js:143
        target[key] = obj[key];
                    ^

TypeError: Cannot assign to read only property 'name' of function compiled(locals) {
      var lcls;
      if (locals && contextLength) {
        lcls = utils.extend({}...<omitted>... }
    at Object.exports.extend (/home/parkle/dev/koa-error/node_modules/swig/lib/utils.js:143:21)
    at compile (/home/parkle/dev/koa-error/node_modules/swig/lib/swig.js:622:11)
    at Object.compileFile (/home/parkle/dev/koa-error/node_modules/swig/lib/swig.js:696:17)
    at error (/home/parkle/dev/koa-error/index.js:28:21)
    at Object.<anonymous> (/home/parkle/dev/koa-error/example.js:10:9)
    at Module._compile (module.js:435:26)
    at Object.Module._extensions..js (module.js:442:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:311:12)
    at Function.Module.runMain (module.js:467:10)

Would be great if koa-error could be used in strict mode, thanks!

using err.expose and NODE_ENV

Since I am building an API I would like to have my errors to be descriptive in test and production environment too.

I noticed the use of err.expose, can you show me an use case for example of a signin error?