弹簧数据与dbref的mongodb查找

我正在使用MongoDB（3.4）与Spring数据。当我使用查找操作时，我得到不正确的结果。收集操作如下：弹簧数据与dbref的mongodb查找

@Document 
public class Employee { 
    @Id 
    String id; 
    String name; 
    @DBRef 
    EmpAddress address; 

    String city;  //redundant, but intentionally 
    //getters and setters 
} 

@Document 
public class EmpAddress { 
    @Id 
    String id; 

    String city; 
    //getters and setters 
}

DB填充了以下数据

Employees [{ "_id" : { "$oid" : "597b557cfe4b9104e8409f2a"} , "_class" : "com.example.Employee" , "name" : "PKM1" , "city" : "NYC" , "address" : { "$ref" : "empAddress" , "$id" : { "$oid" : "597b557bfe4b9104e8409f25"}}}, { "_id" : { "$oid" : "597b557cfe4b9104e8409f2b"} , "_class" : "com.example.Employee" , "name" : "PKM2" , "city" : "SFO" , "address" : { "$ref" : "empAddress" , "$id" : { "$oid" : "597b557bfe4b9104e8409f26"}}}, { "_id" : { "$oid" : "597b557cfe4b9104e8409f2c"} , "_class" : "com.example.Employee" , "name" : "PKM3" , "city" : "LA" , "address" : { "$ref" : "empAddress" , "$id" : { "$oid" : "597b557bfe4b9104e8409f27"}}}, { "_id" : { "$oid" : "597b557cfe4b9104e8409f2d"} , "_class" : "com.example.Employee" , "name" : "PKM4" , "city" : "SFO" , "address" : { "$ref" : "empAddress" , "$id" : { "$oid" : "597b557bfe4b9104e8409f28"}}}, { "_id" : { "$oid" : "597b557cfe4b9104e8409f2e"} , "_class" : "com.example.Employee" , "name" : "PKM5" , "city" : "NYC" , "address" : { "$ref" : "empAddress" , "$id" : { "$oid" : "597b557bfe4b9104e8409f29"}}}] 



Cities [{ "_id" : { "$oid" : "597b557bfe4b9104e8409f25"} , "_class" : "com.example.EmpAddress" , "city" : "NYC"}, { "_id" : { "$oid" : "597b557bfe4b9104e8409f26"} , "_class" : "com.example.EmpAddress" , "city" : "SFO"}, { "_id" : { "$oid" : "597b557bfe4b9104e8409f27"} , "_class" : "com.example.EmpAddress" , "city" : "LA"}, { "_id" : { "$oid" : "597b557bfe4b9104e8409f28"} , "_class" : "com.example.EmpAddress" , "city" : "SFO"}, { "_id" : { "$oid" : "597b557bfe4b9104e8409f29"} , "_class" : "com.example.EmpAddress" , "city" : "NYC"}]

当我查找如下

MatchOperation match = Aggregation.match(Criteria.where("name").is("PKM1")); 
LookupOperation lookup = LookupOperation.newLookup().from("empAddress").localField("address.$id").foreignField("id").as("emp_loc"); 
Aggregation aggregation = Aggregation.newAggregation(match, lookup); 
AggregationResults<DBObject> result = mongoTemplate.aggregate(aggregation, "employee", DBObject.class);

结果是：

[{ "_id" : { "$oid" : "597b557cfe4b9104e8409f2a"} , "_class" : "com.example.Employee" , "name" : "PKM1" , "city" : "NYC" , "address" : { "$ref" : "empAddress" , "$id" : { "$oid" : "597b557bfe4b9104e8409f25"}} , "emp_loc" : [ { "_id" : { "$oid" : "597b557bfe4b9104e8409f25"} , "_class" : "com.example.EmpAddress" , "city" : "NYC"} , { "_id" : { "$oid" : "597b557bfe4b9104e8409f26"} , "_class" : "com.example.EmpAddress" , "city" : "SFO"} , { "_id" : { "$oid" : "597b557bfe4b9104e8409f27"} , "_class" : "com.example.EmpAddress" , "city" : "LA"} , { "_id" : { "$oid" : "597b557bfe4b9104e8409f28"} , "_class" : "com.example.EmpAddress" , "city" : "SFO"} , { "_id" : { "$oid" : "597b557bfe4b9104e8409f29"} , "_class" : "com.example.EmpAddress" , "city" : "NYC"}]}]

以上结果不正确，因为所有城市都已上市。

但是，如果我这样做查找另一个字段我得到正确的结果

LookupOperation lookup = LookupOperation.newLookup().from("empAddress").localField("city").foreignField("city").as("emp_loc");

结果如下：

[{ "_id" : { "$oid" : "597b557cfe4b9104e8409f2a"} , "_class" : "com.example.Employee" , "name" : "PKM1" , "city" : "NYC" , "address" : { "$ref" : "empAddress" , "$id" : { "$oid" : "597b557bfe4b9104e8409f25"}} , "emp_loc" : [ { "_id" : { "$oid" : "597b557bfe4b9104e8409f25"} , "_class" : "com.example.EmpAddress" , "city" : "NYC"} , { "_id" : { "$oid" : "597b557bfe4b9104e8409f29"} , "_class" : "com.example.EmpAddress" , "city" : "NYC"}]}]

我如何当我查找使用ID在第二个结果？

来源

2017-07-28 pkm

这是DBref的一个问题。由于mongoDB 3.4，除了$ match阶段外，不能在聚合管道中使用DBRef。

该查询返回所有的结果，因为id为空，我有同样的问题。

您应该创建手动引用来防止此问题。

你可以在这个答案中阅读更多关于此：https://stackoverflow.com/a/41677055/4023844

来源

2017-09-15 10:33:02

弹簧数据与dbref的mongodb查找

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