Spring数据mongodb - 'cursor'选项是必需的 [英] Spring data mongodb - The 'cursor' option is required

问题描述

我正在尝试使用Spring Data MongoDB 3.6-rc4执行聚合操作。

I am trying to execute an aggregate operation using Spring Data MongoDB 3.6-rc4.

Aggregation agg = newAggregation(
    lookup("orders", "orderId", "_id", "order") 
);
List<BasicDBObject> results = mongoOperations.aggregate(agg, "transactions", BasicDBObject.class).getMappedResults();

但运行查询时出现以下错误

But get the following error on running the query

2017-11-24 17:03:41,539 WARN  org.springframework.data.mongodb.core.MongoTemplate : Command execution of { "aggregate" : "transactions" , "pipeline" : [ { "$lookup" : { "from" : "orders" , "localField" : "orderId" , "foreignField" : "_id" , "as" : "order"}}]} failed: The 'cursor' option is required, except for aggregate with the explain argument
2017-11-24 17:03:41,574 ERROR org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.InvalidDataAccessApiUsageException: Command execution failed:  Error [The 'cursor' option is required, except for aggregate with the explain argument], Command = { "aggregate" : "transactions" , "pipeline" : [ { "$lookup" : { "from" : "orders" , "localField" : "orderId" , "foreignField" : "_id" , "as" : "order"}}]}; nested exception is com.mongodb.MongoCommandException: Command failed with error 9: 'The 'cursor' option is required, except for aggregate with the explain argument' on server localhost:27017. The full response is { "ok" : 0.0, "errmsg" : "The 'cursor' option is required, except for aggregate with the explain argument", "code" : 9, "codeName" : "FailedToParse" }] with root cause
com.mongodb.MongoCommandException: Command failed with error 9: 'The 'cursor' option is required, except for aggregate with the explain argument' on server localhost:27017. The full response is { "ok" : 0.0, "errmsg" : "The 'cursor' option is required, except for aggregate with the explain argument", "code" : 9, "codeName" : "FailedToParse" }
    at com.mongodb.CommandResult.getException(CommandResult.java:80) ~[mongo-java-driver-3.5.0.jar:na]
    at com.mongodb.CommandResult.throwOnError(CommandResult.java:94) ~[mongo-java-driver-3.5.0.jar:na]
    at org.springframework.data.mongodb.core.MongoTemplate.handleCommandError(MongoTemplate.java:2100) ~[spring-data-mongodb-1.10.8.RELEASE.jar:na]
    at org.springframework.data.mongodb.core.MongoTemplate.aggregate(MongoTemplate.java:1577) ~[spring-data-mongodb-1.10.8.RELEASE.jar:na]
    at org.springframework.data.mongodb.core.MongoTemplate.aggregate(MongoTemplate.java:1505) ~[spring-data-mongodb-1.10.8.RELEASE.jar:na]

提前致谢!!

推荐答案

MongoDB在3.6中更改了聚合命令的工作原理。聚合现在需要一个游标。我们改编了Spring Data MongoDB 2.1 ，但不是以前的版本。

MongoDB changed in 3.6 how the aggregation command works. Aggregations require now a cursor. We adapted Spring Data MongoDB 2.1 but not previous versions.

必须通过集合的 aggregate（...）方法调用聚合，而不是直接调用命令。这也是我们没有向后移动这一变化的原因。 executeCommand（...）不再被调用，我们不想破坏bug修复版本中的兼容性。

Aggregations must be invoked through the collection's aggregate(…) method instead of calling the command directly. This is also the reason why we didn't backport the change. executeCommand(…) is no longer called and we don't want to break compatibility in a bugfix release.

最简单的方法是覆盖 aggregate（...）方法并调用适当的方法， DBCollection.aggregate（...）使用映射的聚合管道。

The easiest approach for you can be to override the aggregate(…) method and call the appropriate method, DBCollection.aggregate(…) with the mapped aggregation pipeline.

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