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Mongodb使用另一个查询的结果查询数据库

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Mongodb使用另一个查询的结果查询数据库,mongodb,mongodb-query,aggregation-framework,Mongodb,Mongodb Query,Aggregation Framework,我对同一集合有多个查询： 第一次查询： db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0}) { "currentStep" : [ "flowkuec8ta1o" ] } db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'

我对同一集合有多个查询：

第一次查询：

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
第一次查询结果

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
我正在第二次查询中使用第一个查询结果“flowkuec8ta1o”（查询1结果中的“currentStep”用作下面第二次查询中键“previousStep”的值）：

第二次查询：

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
第二次查询结果：

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
如何将两个查询合并为一个？
请不要在这个问题上作记号。我尝试了那个问题的解决方案，但并没有给我想要的结果。有人能帮我吗

附加示例文档1（其中“currentStep”取自）：

附加示例文档2（其中从查询1获取的“currentStep”值用作第二个查询中的“previousStep”）

样本输出：

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}
根据@Fanparks请求添加示例文档：
以下两个文档与第一个查询匹配（以获取“currentStep”）
文件1:

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
文件2:

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
以下文档与第二个查询匹配（其中“previousStep”与从第一个查询中获取的“currentStep”匹配）
文件1:

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
文件2:

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
文件3:

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
文件4:

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
所需输出：

db.getCollection('messagelogs').find({'intents.intent':'General_Positive_Feedback'},{'currentStep':1,'_id':0})    

{
"currentStep" : [ 
    "flowkuec8ta1o"
]
}

db.getCollection('messagelogs').find({'previousStep':'flow1pemwl7ws'},{'userMessage':1})  

{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
 }  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Liked It :)",
"intents": [{
    "_id": ObjectId("5cec2dc69b806c4a00f91f17"),
    "intent": "General_Positive_Feedback",
    "score": "0.9774518966674806"
}]
}  

{
"currentStep": [
    "flowkuec8ta1o"
],
"previousStep": [
    "conditioncplwf7pw1",
    "condition00yokr6jv",
    "conditionzq9koi6i3"
],
"userMessage": "Just Okay, Could Be better",
"intents": [{
    "_id": ObjectId("5cec2f1a9b806c4a00f91f41"),
    "intent": "General_Positive_Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "ILikedIt#1",
"intents": [{
    "_id": ObjectId("5cec2dd29b806c4a00f91f19"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "JustOkayCouldBeBetter#1",
"intents": [{
    "_id": ObjectId("5cec2f2b9b806c4a00f91f43"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'mGivingAPositiveFeedback",
"intents": [{
    "_id": ObjectId("5ced84e2fdf046078c85d9cb"),
    "intent": "Feedback",
    "score": "1"
}]
}  

{
"currentStep": [],
"previousStep": [
    "flowkuec8ta1o"
],
"userMessage": "I'm giving a positive feedback for the second time!",
"intents": [{
    "_id": ObjectId("5cede37dfdf046078c85d9e0"),
    "intent": "Feedback",
    "score": "1"
}]
}  

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
**实际产出：**

/* 1 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 2 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 3 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 4 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}

/* 5 */
{
"_id" : ObjectId("5cec2dd29b806c4a00f91f18"),
"userMessage" : "ILikedIt#1"
}

/* 6 */
{
"_id" : ObjectId("5cec2f2b9b806c4a00f91f42"),
"userMessage" : "JustOkayCouldBeBetter#1"
}

/* 7 */
{
"_id" : ObjectId("5ced84e2fdf046078c85d9ca"),
"userMessage" : "I'mGivingAPositiveFeedback"
}

/* 8 */
{
"_id" : ObjectId("5cede37dfdf046078c85d9df"),
"userMessage" : "I'm giving a positive feedback for the second time!"
}
您可以使用下面的聚合

db.getCollection('messagelogs').aggregate([
  { "$match": { "intents.intent": "General_Positive_Feedback" }},
  { "$lookup": {
      "from": "messagelogs",
      "let": { "currentStep": "$currentStep" },
      "pipeline": [
        { "$match": { "$expr": { "$eq": ["$previousStep", "$$currentStep"] }}},
        { "$project": { "userMessage": 1 }}
      ],
      "as": "previousStep"
    }},
  { "$unwind": "$previousStep" },
  { "$replaceRoot": { "newRoot": "$previousStep" }},
  { "$group": {
    "_id": "$userMessage",
    "id": { "$first": "$_id" }
  }},
  { "$project": {
    "_id": "$id",
    "userMessage": "$_id"
  }}
])

请解释为什么要合并这两个查询？您的上述两个问题之间有什么关系？我看不到
我正在使用第一个查询结果'flowkuec8ta1o'进行第二次查询
。你在第二部中在哪里用的？发布一些样本集和您想要的输出。@Fanpark我已根据您的要求更新了问题。请看一看，如果在
as
表达式中找到多个
上一步
，那么它可能会给您多条记录，因为我们在这里做的下一步是
$unwind
。更新了我的回答您能用示例文档和输出解释一下吗，你能看一下这个问题吗？：我想知道在两个日期之间提取文档的正确方法。你能看一下吗？