Add support for headers in errors

closes: #668
closes: #571
This commit is contained in:
Lee Bousfield 2016-02-29 13:22:59 -07:00 committed by Jonathan Ong
parent 8e7e1c3023
commit c826467560
3 changed files with 80 additions and 1 deletions

44
docs/error-handling.md Normal file
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@ -0,0 +1,44 @@
# Error Handling
## Try-Catch
Using generators means that you can try-catch `next`. For example,
this example prepends all error messages with "Error: "
```js
app.use(function*(next){
try {
yield next;
} catch (error) {
error.message = 'Error: ' + error.message;
throw error;
}
});
```
### Default Error Handler
The default error handler is essentially a try-catch at
the very beginning of the middleware chain. To use a
different error handler, simply put another try-catch at
the beginning of the middleware chain, and handle the error
there. However, the default error handler is good enough for
most use cases. It will use a status code of `err.status`,
or by default 500. If `err.expose` is true, then `err.message`
will be the reply. Otherwise, a message generated from the
error code will be used (e.g. for the code 500 the message
"Internal Server Error" will be used). All headers will be
cleared from the request, but any headers in `err.headers`
will then be set. You can use a try-catch, as specified
above, to add a header to this list.
## The Error Event
Error handlers can be specified with `app.on('error')`.
If no error handler is specified, a default error handler
is used. Error handlers recieve all errors that make their
way back through the middleware chain, if an error is caught
and not thrown again, it will not be handled by the error
handler. If not error event handler is specified, then
`app.onerror` will be used, which simply log the error if
`error.expose` is true and `app.silent` is false.

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@ -117,8 +117,9 @@ var proto = module.exports = {
return;
}
// unset all headers
// unset all headers, and set those specified
this.res._headers = {};
this.set(err.headers);
// force text/plain
this.type = 'text';

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@ -52,6 +52,40 @@ describe('ctx.onerror(err)', function(){
})
})
it('should set headers specified in the error', function(done){
var app = koa();
app.use(function *(next){
this.set('Vary', 'Accept-Encoding');
this.set('X-CSRF-Token', 'asdf');
this.body = 'response';
throw Object.assign(new Error('boom'), {
status: 418,
expose: true,
headers: {
'X-New-Header': 'Value'
}
})
})
var server = app.listen();
request(server)
.get('/')
.expect(418)
.expect('Content-Type', 'text/plain; charset=utf-8')
.expect('X-New-Header', 'Value')
.end(function(err, res){
if (err) return done(err);
res.headers.should.not.have.property('vary');
res.headers.should.not.have.property('x-csrf-token');
done();
})
})
describe('when invalid err.status', function(){
describe('not number', function(){
it('should respond 500', function(done){