如何将以下 MongoDB 查询转换为我的 Java Spring 应用程序要使用的查询？我找不到通过提供的 lookup 使用 pipeline 的方法方法。

这是我试图转换的查询。我还想指出，我没有使用 $unwind，因为我希望 deliveryZipCodeTimings 保留为返回对象中的分组集合。

db.getCollection('fulfillmentChannel').aggregate([
    {
        $match: {
            "dayOfWeek": "SOME_VARIABLE_STRING_1"
        }
    },
    {
        $lookup: {
            from: "deliveryZipCodeTiming",
            let: { location_id: "$fulfillmentLocationId" },
            pipeline: [{
                $match: {
                    $expr: {
                        $and: [
                            {$eq: ["$fulfillmentLocationId", "$$location_id"]},
                            {$eq: ["$zipCode", "SOME_VARIABLE_STRING_2"]}
                        ]
                    }
                }
            },
            { 
                $project: { _id: 0, zipCode: 1, cutoffTime: 1 } 
            }],
            as: "deliveryZipCodeTimings"
        }
    },
    {
        $match: {
            "deliveryZipCodeTimings": {$ne: []}
        }
    }
])

最佳答案

根据@dnickless 提供的信息，我能够解决这个问题。我会发布完整的解决方案，希望它能在将来帮助其他人。

我正在使用 mongodb-driver:3.6.4

首先，我必须创建一个自定义聚合操作类，以便我可以传入自定义 JSON mongodb 查询以用于聚合操作。这将允许我在 $lookup 中使用 pipeline，我正在使用的驱动程序版本不支持它。

public class CustomProjectAggregationOperation implements AggregationOperation {
    private String jsonOperation;

    public CustomProjectAggregationOperation(String jsonOperation) {
        this.jsonOperation = jsonOperation;
    }

    @Override
    public Document toDocument(AggregationOperationContext aggregationOperationContext) {
        return aggregationOperationContext.getMappedObject(Document.parse(jsonOperation));
    }
}

现在我们已经能够将自定义 JSON 查询传递到我们的 mongodb spring 实现中，剩下的就是将这些值插入到 TypedAggregation 中。查询。

public List<FulfillmentChannel> getFulfillmentChannels(
    String SOME_VARIABLE_STRING_1, 
    String SOME_VARIABLE_STRING_2) {

    AggregationOperation match = Aggregation.match(
            Criteria.where("dayOfWeek").is(SOME_VARIABLE_STRING_1));
    AggregationOperation match2 = Aggregation.match(
            Criteria.where("deliveryZipCodeTimings").ne(Collections.EMPTY_LIST));
    String query =
            "{ $lookup: { " +
                    "from: 'deliveryZipCodeTiming'," +
                    "let: { location_id: '$fulfillmentLocationId' }," +
                    "pipeline: [{" +
                    "$match: {$expr: {$and: [" +
                    "{ $eq: ['$fulfillmentLocationId', '$$location_id']}," +
                    "{ $eq: ['$zipCode', '" + SOME_VARIABLE_STRING_2 + "']}]}}}," +
                    "{ $project: { _id: 0, zipCode: 1, cutoffTime: 1 } }]," +
                    "as: 'deliveryZipCodeTimings'}}";

    TypedAggregation<FulfillmentChannel> aggregation = Aggregation.newAggregation(
            FulfillmentChannel.class,
            match,
            new CustomProjectAggregationOperation(query),
            match2
    );

    AggregationResults<FulfillmentChannel> results = 
        mongoTemplate.aggregate(aggregation, FulfillmentChannel.class);
    return results.getMappedResults();
}

关于具有管道聚合的 Spring Data MongoDB 查找，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51107626/