I am making a server using nodejs
& express in which user can request some data and server send response. But, the data is array and I want to send a json response to the user. So, I used forEach()
method of array and use Object.assign()
, so that I can get object. But the problem is I cannot use 'index' argument of forEach()
method while 'value' argument is properly getting used inside the callback function. When I use only 'index' argument, then my code runs ok but I want to use both arguments at the same time.
route.get('/getGPX/:number', passport.authenticate('jwt', { session: false }), (req, res) => {
gpx.find({ username: req.user.username }, (err, result) => {
if (err) console.log(err);
if (result) {
if (result.length === 0) {
res.end();
console.log('ended')
}
else {
var jsonRes = {};
result.forEach((value, index) => {
I can use 'value' but not 'index' from the arguments
jsonRes = Object.assign({ index: value.data }, jsonRes);
})
res.json({data: jsonRes});
}
}
})
I even tried using global var
, but even it's not working, how can I use index as well as value argument at the same time
What is the JSON structure that you want ?
if you want a json like :
{
0: "my first value",
1: "second"
}
You just miss []
around index, here you put 'index' as a key not the value of index. So you override the index key in each iteration.
Here is the code that use the value of index as a key in a json.
jsonRes = Object.assign({[index]: value.data}, jsonRes)
See here for a working example with more examples : https://repl.it/@Benoit_Vasseur/nodejs-playground
Object.assign
mutates the left-most parameter. it does not produce a new object. Since you are passing a literal object every time the jsonRes is going to be the last result.
Put jsonRes in the left instead - Object.assign(jsonRes, {index: value.data})
You might want to use a simple reduce
instead of forEach
and Object.assign
:
} else {
var jsonRes = result.reduce((r, v, i) => {r[i] = v.data; return r}, {});
res.json({data: jsonRes});
}
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