how to use $lookup stage in java with spring data mongodb? [duplicate]

问题:

This question already has an answer here:

• lookup in mongodb aggregation 1 answer

Up to last version of spring i have seen lot of stack over flow questions which shows there is no support for this operation in spring-data-mongodb is there any support for this operation in new spring-data-mongodb 1.10.0

db.orders.aggregate([         {           $lookup:             {               from: "inventory",               localField: "item",               foreignField: "sku",               as: "inventory_docs"             }        }     ]) 

回答1:

Lookup support has been there since 1.9 version.

LookupOperation lookupOperation = LookupOperation.newLookup().                                    from("inventory").                                    localField("item").                                    foreignField("sku").                                    as("inventory_docs"); Aggregation aggregation = Aggregation.newAggregation(lookupOperation); List<BasicDBObject> results = mongoOperations.aggregate(aggregation, "orders", BasicDBObject.class).getMappedResults(); 

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