MongoDB Aggregation命令转换为Java代码 [英] MongoDB Aggregation command to Java code
问题描述
这是我的mongodb shell命令:
This is my mongodb shell command:
db.dais_employee.aggregate([
{
"$redact": {
"$cond": {
"if": {
"$gt": [
{ "$subtract": [ "$modifiedon", "$createdon" ] },
1000 * 60 * 60 * 24
]
},
"then": "$$KEEP",
"else": "$$PRUNE"
}
}
}
])
效果很好.
我需要在Java中使用此MongoDB命令,并且需要有关将MongoDB Aggregation框架与Java驱动程序配合使用的帮助.
I need to work this MongoDB command in java and I need help for using MongoDB Aggregation framework with java driver.
当我尝试使用Java驱动程序运行此命令时:
When I am trying to run this command using java driver:
AggregateIterable<Document> iterable = collection.aggregate(asList(
new Document("$redact",
new Document("$cond",
new Document("if",
new Document("$gt",
asList(new Document("$subtract",
asList("$modifiedon", "$createdon")
),1000 * 60 * 60 * 24)
).append("then", "$$KEEP")
.append("else", "$$PRUNE")
)
)
)
));
会引发异常,
Exception in thread "main" com.mongodb.MongoCommandException: Command failed with error 15990: 'exception: this object is already an operator expression, and can't be used as a document expression (at 'then')' on server 192.168.1.127:27017. The full response is { "errmsg" : "exception: this object is already an operator expression, and can't be used as a document expression (at 'then')", "code" : 15990, "ok" : 0.0 }
at com.mongodb.connection.ProtocolHelper.getCommandFailureException(ProtocolHelper.java:115)
at com.mongodb.connection.CommandProtocol.execute(CommandProtocol.java:114)
at com.mongodb.connection.DefaultServer$DefaultServerProtocolExecutor.execute(DefaultServer.java:159)
at com.mongodb.connection.DefaultServerConnection.executeProtocol(DefaultServerConnection.java:286)
at com.mongodb.connection.DefaultServerConnection.command(DefaultServerConnection.java:173)
at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:215)
at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:206)
at com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol(CommandOperationHelper.java:112)
at com.mongodb.operation.AggregateOperation$1.call(AggregateOperation.java:227)
at com.mongodb.operation.AggregateOperation$1.call(AggregateOperation.java:223)
at com.mongodb.operation.OperationHelper.withConnectionSource(OperationHelper.java:239)
at com.mongodb.operation.OperationHelper.withConnection(OperationHelper.java:212)
at com.mongodb.operation.AggregateOperation.execute(AggregateOperation.java:223)
at com.mongodb.operation.AggregateOperation.execute(AggregateOperation.java:65)
at com.mongodb.Mongo.execute(Mongo.java:772)
at com.mongodb.Mongo$2.execute(Mongo.java:759)
at com.mongodb.OperationIterable.iterator(OperationIterable.java:47)
at com.mongodb.OperationIterable.forEach(OperationIterable.java:70)
at com.mongodb.AggregateIterableImpl.forEach(AggregateIterableImpl.java:117)
at threadpack.queryBtDates.main(queryBtDates.java:88)
帮助我找出错误,或提供正确的代码以使用Java驱动程序运行此命令.
Help me to find out the error, or give correct code to run this command using java Driver.
推荐答案
asList("$modifiedon",1000)
应该为asList("$modifiedon","$createdon")
.
完成编辑后.可以看到问题是您将"then"和"else"附加到"$ gt"文档而不是"if".
As you have done the edit. Can see that the problem is you are appending the "then" and "else" to the "$gt" document rather than "if".
所以代替:
AggregateIterable<Document> iterable = collection.aggregate(
asList( new Document("$redact",
new Document("$cond",
new Document("if",
new Document("$gt",
asList(new Document("$subtract",
asList("$modifiedon", "$createdon")
),1000 * 60 * 60 * 24)
).append("then", "$$KEEP")
.append("else", "$$PRUNE")
)
)
)
));
您应该这样做:
AggregateIterable<Document> iterable = collection.aggregate(
asList( new Document("$redact",
new Document("$cond",
new Document("if",
new Document("$gt",
asList(new Document("$subtract",
asList("$modifiedon", "$createdon")
),1000 * 60 * 60 * 24)
)
).append("then", "$$KEEP")
.append("else", "$$PRUNE")
)
)
));
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