Question

I have a api (in NODEJS) response that gives back an array:

res.json(friends)
[
    {
        "id": 7795239,
        "username": "janesmith"
    },
    {
        "id": 1363327,
        "username": "johnsmith"
    }
]

But when I want to iterate through the array before sending this response, I cannot find the way to do this. users.length does not exist, for(var key users) doens't work either.

How to solve this?

edit: the code where it gets the array:

User.find({}, function(err, users){
    if(err) res.send(err);
    var friends;
    var result = 'this will hold the result';

    for(var key in users){
        if(users[key].username == req.decoded.username) {
            friends = users[key].friends;
        }
    }

    // here I want to do things with the list of friends, so this is the place where I need to iterate over it

    res.json(result);
});

This is the log result for users and err

users: 
    [
        {
            "_id": "5710b02c7787794009325f62",
            "username": "demouser",
            "__v": 0,
            "friends": 
            [
                {
                    "username": "janesmith",
                    "id": 7795239
                },
                {
                    "username": "johnsmith",
                    "id": 1363327
                }
            ]
        }
    ]   
err: null

This is the log of the keys:

toObject
toJSON
items
db
discriminators
__v
id
_id
friends
password
username
userID
schema
collection
comparePassword
save
$__delta
$__version
increment
$__where
remove
model
$__buildDoc
init
$__storeShard
hook
pre
post
removePre
_lazySetupHooks
update
set
$__shouldModify
$__set
getValue
setValue
get
$__path
markModified
$__try
modifiedPaths
isModified
isDirectModified
isInit
isSelected
validate
invalidate
$__reset
$__dirty
$__setSchema
$__registerHooks
$__error
$__doQueue
$toObject
inspect
toString
equals
populate
populated
$__fullPath
domain
_events
_maxListeners
setMaxListeners
getMaxListeners
emit
addListener
on
once
removeListener
removeAllListeners
listeners
listenerCount

Answer 1

Simply initialize your results variable as an array and push the users you wish to match into that array and return it.

User.find({}, function(err, users){
    if (err) res.send(err);

    var result = [];
    for (var key in users) {
        if (users[key].username == req.decoded.username) {
            var friends = users[key].friends;
            for (var i = 0; i < friends.length; i++) {
                // Do stuff with each friend here, as required.
            }

            result.push(users[key]);

            // OR this, depending on whether it is users or friends you're trying to return.
            result.push(friends[i]);
        }
    }

    res.json(result);
});

Answer 2

似乎API的auto f = input.begin(), l = input.end(); bool ok = qi::phrase_parse(f, l, grammar, qi::space); if (ok) std::cout << "Parse success\n"; else std::cout << "Parse failed\n"; if (f!=l) std::cout << "Trailing unparsed input: '" << std::string(f, l) << "'\n";方法正在返回一个对象而不是一个数组。

find

Answer 3

var array1 = ['a', 'b', 'c'];

array1.forEach(function(element) {
  console.log(element);
});

// expected output: "a"
// expected output: "b"
// expected output: "c"

Unable to iterate through JSON array

3 个答案: