我有一个对象数组，只包含ObjectIDs，希望能够在集合中搜索所有这些ID对应的文档。
var array = [{ _id: 5551e59be360594cd3319644 },
{ _id: 5551e59be360594cd3319631 },
{ _id: 5551e59be360594cd33195d2 },
{ _id: 5551e59be360594cd3319627 }];
以下是我目前为了得到我的结果所做的事情：
for (var i = 0; i < array.length; i++) {
db.collection('test').findOne({_id:array[i]._id}, function(err, matched) {
console.log(matched);
});
我尝试使用$in运算符，但没有成功，因为它不是一个包含ID的数组，而是一个包含这些ID的对象数组。
有没有另一种方法只需进行一个数据库查询就可以完成，因为在for循环中执行太多的数据库查询不是一个好主意。
编辑 现在我尝试使用map方法（像@chrisdam解释的那样），所以我有了一个ID的数组，但当我将它传递给find方法时，我得到了这个结果:
编辑2
不要理会我的第一个编辑。 find()只返回一个光标，而不是文档本身。 所以我使用了toArray()。感谢@chrisdam的帮助！
{ db:
{ domain: null,
_events: {},
_maxListeners: undefined,
databaseName: 'test',
serverConfig: {
domain: null,
_events: {},
_maxListeners: undefined,
auth: [Getter],
_callBackStore: [Object],
_commandsStore: [Object],
_dbStore: [Object],
host: 'localhost',
port: 27017,
options: [Object],
internalMaster: true,
connected: true,
poolSize: 5,
disableDriverBSONSizeCheck: false,
_used: true,
replicasetInstance: null,
emitOpen: false,
ssl: false,
sslValidate: false,
sslCA: null,
sslCert: undefined,
sslKey: undefined,
sslPass: undefined,
serverCapabilities: [Object],
name: 'localhost:27017',
socketOptions: [Object],
logger: [Object],
eventHandlers: [Object],
_serverState: 'connected',
_state: [Object],
recordQueryStats: false,
socketTimeoutMS: [Getter/Setter],
_readPreference: [Object],
db: [Circular],
dbInstances: [Object],
connectionPool: [Object],
isMasterDoc: [Object] },
options: {
read_preference_tags: null,
read_preference: 'primary',
url: 'mongodb://localhost:27017/test',
native_parser: true,
readPreference: [Object],
safe: false,
w: 1 },
_applicationClosed: false,
slaveOk: false,
bufferMaxEntries: -1,
native_parser: true,
bsonLib: {
BSON: [Object],
Long: [Object],
ObjectID: [Object],
DBRef: [Object],
Code: [Object],
Timestamp: [Object],
Binary: [Object],
Double: [Object],
MaxKey: [Object],
MinKey: [Object],
Symbol: [Object] },
bson: { promoteLongs: true },
bson_deserializer: {
Code: [Object],
Symbol: [Object],
BSON: [Object],
DBRef: [Object],
Binary: [Object],
ObjectID: [Object],
Long: [Object],
Timestamp: [Object],
Double: [Object],
MinKey: [Object],
MaxKey: [Object],
promoteLongs: true },
bson_serializer: {
Code: [Object],
Symbol: [Object],
BSON: [Object],
DBRef: [Object],
Binary: [Object],
ObjectID: [Object],
Long: [Object],
Timestamp: [Object],
Double: [Object],
MinKey: [Object],
MaxKey: [Object],
promoteLongs: true },
_state: 'connected',
pkFactory: {
[Function: ObjectID]
index: 13651524,
createPk: [Function: createPk],
createFromTime: [Function: createFromTime],
createFromHexString: [Function: createFromHexString],
isValid: [Function: isValid],
ObjectID: [Circular],
ObjectId: [Circular] },
forceServerObjectId: false,
safe: false,
notReplied: {},
isInitializing: true,
openCalled: true,
commands: [],
logger: { error: [Function], log: [Function], debug: [Function] },
tag: 1431517732801,
eventHandlers: {
error: [],
parseError: [],
poolReady: [],
message: [],
close: [] },
serializeFunctions: false,
raw: false,
recordQueryStats: false,
retryMiliSeconds: 1000,
numberOfRetries: 60,
readPreference: { _type: 'ReadPreference', mode: 'primary', tags: undefined } },
collection: {
db: {
domain: null,
_events: {},
_maxListeners: undefined,
databaseName: 'test',
serverConfig: [Object],
options: [Object],
_applicationClosed: false,
slaveOk: false,
bufferMaxEntries: -1,
native_parser: true,
bsonLib: [Object],
bson: [Object],
bson_deserializer: [Object],
bson_serializer: [Object],
_state: 'connected',
pkFactory: [Object],
forceServerObjectId: false,
safe: false,
notReplied: {},
isInitializing: true,
openCalled: true,
commands: [],
logger: [Object],
tag: 1431517732801,
eventHandlers: [Object],
serializeFunctions: false,
raw: false,
recordQueryStats: false,
retryMiliSeconds: 1000,
numberOfRetries: 60,
readPreference: [Object] },
collectionName: 'sick',
internalHint: null,
opts: {},
slaveOk: false,
serializeFunctions: false,
raw: false,
readPreference: { _type: 'ReadPreference', mode: 'primary', tags: undefined },
pkFactory: {
[Function: ObjectID]
index: 13651524,
createPk: [Function: createPk],
createFromTime: [Function: createFromTime],
createFromHexString: [Function: createFromHexString],
isValid: [Function: isValid],
ObjectID: [Circular],
ObjectId: [Circular] },
serverCapabilities: undefined },
selector: { _id: { '$in': [Object] } },
fields: undefined,
skipValue: 0,
limitValue: 0,
sortValue: undefined,
hint: null,
explainValue: undefined,
snapshot: undefined,
timeout: true,
tailable: undefined,
awaitdata: undefined,
oplogReplay: undefined,
numberOfRetries: 5,
currentNumberOfRetries: 5,
batchSizeValue: 0,
raw: false,
readPreference: { _type: 'ReadPreference', mode: 'primary', tags: undefined },
returnKey: undefined,
maxScan: undefined,
min: undefined,
max: undefined,
showDiskLoc: undefined,
comment: undefined,
tailableRetryInterval: 100,
exhaust: false,
partial: false,
slaveOk: false,
maxTimeMSValue: undefined,
connection: undefined,
transforms: undefined,
totalNumberOfRecords: 0,
items: [],
cursorId: { _bsontype: 'Long', low_: 0, high_: 0 },
dbName: undefined,
state: 0,
queryRun: false,
getMoreTimer: false,
collectionName: 'test.sick' }
$in运算符一起使用。 - sirfz