I have a simple task. Lets say, that user can add a news in a form which has two fields, title and content. Title field must be filled. I can check it on client side but also on server side, for example:
news.js
var _this = module.exports = {
add: (news) => {
return new Promise((resolve, reject) => {
if(!news.title)
reject('Title must be filled!')
//rest of code
})
}
}
this error can be catched in main app.js
app.post('/add_news', (req, resp) => {
var news = req.body.data;
_news.add(news).then(result => {
//send success
}).catch(err => {
//send error
})
})
and I want to catch it on client side:
this.newsService.add(news).subscribe(
result => {
//here ok
},
error => {
//here errors
})
How to do it? What should I send on server side to client? resp.status does not work as I want. Is it maybe a better solution?
Regards
Generally your API should return some error code (number or string, it does not matter), and your angular frontend should handle that error code.
news.js
if (!news.title) {
reject({statusCode: 404, errorCode: 'MISSING_TITLE'});
}
app.js
_news.add(news).then(result => {
//send success
}).catch(err => {
// process only errors with `statusCode` and `errorCode`
if (err.statusCode && err.errorCode) {
resp.status(err.statusCode);
resp.json(err.errorCode);
} else { // otherwise return generic error
resp.status(500);
resp.json('API_ERROR');
}
})
Then on the client side:
this.newsService.add(news).subscribe(
result => {
//here ok
},
error => {
if (error === 'MISSING_TITLE') {
alert('Title field is required!'); // or modify the $scope to show some error message in your template
} else {
alert('An error occurred'); // fallback to general error message when some other message comes
}
})