如何使用此查询隐藏_id，我使用express node.js吗？
我有这个查询，我创建了一个API，但我想隐藏_id。
这是查询：
router.get("/", (req, res) => {
VerbsDE.find({}, { _id: 0 })
.limit(1)
.then(verbs => {
res.send(verbs);
});
});
///////////////////////////////////////////////// /// 这是集合：
[
{
Indicative: {
Present: [
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
}
],
Perfect: [
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
}
],
Past: [
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
}
],
Pluperfect: [
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
}
],
Future_I: [
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
}
],
Future_II: [
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
}
]
},
Imperative: {
Worte: [
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
},
{
_id: "5bb9009249efde355376ad29",
pron: "xxx",
verb: "xxx xxx xxx"
}
]
},
_id: "5bb9009249efde355376ad23",
verbName: "abbilden",
__v: 0
}
];
我试图隐藏_id，但是每次出现错误时，我都想获取数据，而不是使用ID。
答案 0 :(得分：2)
您可以尝试使用投影（https://docs.mongodb.com/manual/reference/method/db.collection.find/）：
{projection: { _id: 0 }}
如：
router.get("/", (req, res) => {
VerbsDE.find({}, {projection: { _id: 0 }})
.limit(1)
.then(verbs => {
res.send(verbs);
});
});
答案 1 :(得分：1)
主要有两种方法：
.map()函数Mongo排除 与您所做的类似，但是您需要正确地声明变量，如果集合是动态的（例如，每个文档中的“预设”，“过去”等发生更改），这可能会很麻烦。
您需要以嵌套属性的方式使用字段选项，只需更改以下内容即可：
router.get("/", (req, res) => {
VerbsDE.find({}, { _id: 0 })
.limit(1)
.then(verbs => {
res.send(verbs);
});
});
对此：
router.get("/", (req, res) => {
VerbsDE.find({}, { _id: 0, __v: 0, 'Indicative.Present._id': 0 })
.limit(1)
.then(verbs => {
res.send(verbs);
});
});
但是，由于文档的 Present，Past等分配，这可能需要重复很多次。现在尝试：
在响应之前使用地图
现在您拥有：
router.get("/", (req, res) => {
VerbsDE.find({}, { _id: 0, __v: 0 })
.limit(1)
.then(verbs => {
// We'll use map before sending the response
res.send(verbs);
});
});
因此，地图功能如下：
function cleanVerbs(verbs) {
return verbs.map(doc => {
// For each doc, make a newDoc
const newDoc = {};
for (const mood in doc) {
// mood will be 'Imperative' 'Indicative', etc.
if (!newDoc[mood]) {
// If out newDoc object does not have 'Imperative', etc. property, assign it as object.
newDoc[mood] = {};
}
if (mood === 'verbName') {
// You have verbName as root property, treat it differently
newDoc[mood] = doc[mood];
break; // Avoid further execution on this cycle
}
for (const time in doc[mood]) {
console.log('MOOD & TIME: ', [mood, time]);
const entries = doc[mood][time];
const newTimeEntries = entries.map(e => {
delete e._id;
return e;
});
// This will set the newTimeEntries for this Mood's time.
newDoc[mood][time] = newTimeEntries;
}
}
return newDoc;
});
}
然后新的get方法将是这样：
router.get("/", (req, res) => {
VerbsDE.find({}, { _id: 0, __v: 0 })
.limit(1)
.then(verbs => {
// We'll use map before sending the response
res.send(cleanVerbs(verbs));
// Try res.json(cleanVerbs(verbs)) instead :)
});
});
只要记住在编写此路由时声明cleanVerbs函数并将其放在作用域内（可在同一文件上访问）即可。
注意： 我强烈建议将Mongo集合架构从以下位置更改：
您需要做什么：
{
_id: "5bb9009249efde355376ad23",
verbName: "abbilden",
grammar: [
Indicative: {
Present: [...],
Past: [...],
},...
],
__v: 0
}
在每个集合的数组中保留心情会简化迭代，例如不对if (mood === 'verbName'){...}函数使用.map(...)测试