如何从 node.js 更新 mongodb 文档？
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how to update a mongodb document from node.js?
提问by IrishGringo
I am trying to update an array in a mongoDB from a node.js program. I am able to modify the array from within node.js, but I can not get the changes to save.
我正在尝试从 node.js 程序更新 mongoDB 中的数组。我可以从 node.js 中修改数组，但无法保存更改。
I think I am doing something very wrong. assistance would be appreciated...
我想我做错了什么。帮助将不胜感激...
回答by tymeJV
Change this line:
改变这一行：
({_id:doc._id},$set:{scores:zz});
To:
到：
({_id:doc._id}, { $set:{scores:zz}} );
This should also probably be wrapped with a callback, to catch errors:
这也应该用回调包装，以捕获错误：
db.schools.update({_id:doc._id}, {$set:{scores:zz}}, function(err, result) {
if (err)
//do something.
});
回答by daemonexmachina
I know it's a bit late to help you now, but maybe others can benefit as new cohorts pass through MongoDB University!
我知道现在帮助你有点晚了，但也许其他人可以随着新的队列通过 MongoDB 大学而受益！
db.schools.updateshould read db.students.update.
db.schools.update应该读db.students.update。
@tymeJV's answer gives the rest:
@tymeJV 的回答给出了其余的：
- Wrap the
$setinside braces:{$set:{scores:zz}} Add a callback function to catch errors:
db.collection( 'students' ).update ( { _id : doc._id }, { $set : { scores:zz } }, function( err, result ) { if ( err ) throw err; } );
- 包裹
$set内花括号：{$set:{scores:zz}} 添加回调函数以捕获错误：
db.collection( 'students' ).update ( { _id : doc._id }, { $set : { scores:zz } }, function( err, result ) { if ( err ) throw err; } );
Funnily enough, I'm actually doing exactly the same assignment right now! I had a different issue that was answered by reading the docs, but I saw this question while googling for it. Hope I helped someone!
有趣的是，我现在实际上正在做完全相同的任务！我有一个不同的问题，通过阅读文档得到了回答，但我在谷歌搜索时看到了这个问题。希望我帮助了某人！
回答by Prathamesh Rasam
var dbName = 'school'
var tableName = 'classA'
MongoClient.connect(dbName, function(err, db) {
if (err)
{
console.log(err);
}
else {
var collection = db.collection(tableName)
collection.update({_id:doc._id}, {$set:{scores:zz}}, function(err, result) {
if (err)
{
console.log(err);
}
else{
console.log(result);
}
});
}
});
回答by Yogesh
I think you should do following code for solving issues
我认为您应该执行以下代码来解决问题
var lowScore = 9999.9;
for ( var i=0; i<doc.scores.length; i++ ) {
if ( doc.scores[i].type == "homework"
&& doc.scores[i].score < lowScore ) {
lowScore = doc.scores[i].score;
}
}
and then update your collection using following query
然后使用以下查询更新您的收藏
collection.update({ "_id":doc._id },
{ $pull : { "scores" : {
$and: [ {"type":"homework"}, { "score":lowScore} ]
} } },
{ "safe":true },
function( err, result ) {
if (err) {
console.log(err);
}
} // update callback
);
for more info you can refer here
有关更多信息，您可以参考 这里
