从MongoDB到Spring Boot聚合框架的聚合

Question

我不熟悉Spring和Mongo。我正在使用Spring Batch获取一些报告。我的查询需要一些MongoItemReader不支持的聚合，所以我根据下面的stackoverflow链接扩展了该类。

如何在Spring批处理中使用MongoItemReader聚合查询

但我的聚合有点问题。我制作的聚合在mongoDB中运行良好，但无法将其转换为Spring mongo聚合。

MongoDb聚合按预期工作。

db.getCollection('orders').aggregate([
  {$match: {orderDate: {$gt:"2021-03-15",$lt: "2021-03-17"}, "status" :{"$in": ["GREEN", "YELLOW"]}}},
  {$group: {_id: {orderDate: "$orderDate", node: "$node", code1:"$code1", code2:"$code2"}, orderUnts: {$sum: 1}}},
  {"$project": {orderDate:"$_id.orderDate", node:"$_id.node", code1:"$_id.code1", code2:"$_id.code2", orderUnts:"$orderUnts"}}
])

Spring蒙戈聚合给出错误。

String[] fields = {"orderDate", "node", "code1", "code2"};
String[] projectionFields = {"orderDate", "orderDate", "code1", "code2"};
MatchOperation matchOp = Aggregation.match(Criteria.where("orderDate").gt(startDate).and("orderDate").lt(endDate).and("status").in("GREEN", "YELLOW"));
GroupOperation groupOp = Aggregation.group(fields).sum("orderUnts").as("_id");
ProjectionOperation projectOp = Aggregation.project(projectionFields);
SortOperation sortOp = Aggregation.sort(Sort.by(Sort.Direction.ASC, "orderDate"));
Aggregation aggregation = Aggregation.newAggregation(matchOp, groupOp, projectOp, sortOp);

我得到下面唯一的字段错误。

Caused by: java.lang.IllegalStateException: An implementation of MongoOperations is required.
at org.springframework.util.Assert.state(Assert.java:76)
at org.springframework.batch.item.data.MongoItemReader.afterPropertiesSet(MongoItemReader.java:238)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1847)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1784)
... 81 common frames omitted

MongoItemReader扩展类。

@Data
public class CustomMongoItemReader<T> extends MongoItemReader<T> {

    private MongoTemplate template;
    private Class<? extends T> type;
    private String collection;
    private MatchOperation matchOperation;
    private GroupOperation groupOperation;
    private ProjectionOperation projectionOperation;
    private SortOperation sortOperation;
    private Aggregation aggregation;

    @Override
    protected Iterator<T> doPageRead() {
        Pageable page = PageRequest.of(this.page, this.pageSize);
        if(matchOperation != null && groupOperation != null) {
            Aggregation agg = Aggregation.newAggregation(matchOperation,
                    groupOperation,
                    projectionOperation,
                    sortOperation,
                    Aggregation.skip(Long.valueOf(page.getPageNumber() * page.getPageSize())),
                    Aggregation.limit(page.getPageSize())
            );
            return (Iterator<T>) template.aggregate(agg, collection, this.type).iterator();
        }
        else {
            return Collections.emptyIterator();
        }
    }
}

如果问题需要更多信息，请告诉我。提前谢谢。

Answer 1

JAVAlang.IllegalStateException：需要实现MongoOperations。

您的条目阅读器扩展了MongoItemReader，这需要MongoOperations（通常是MongoTemplate）。此错误意味着您的项目阅读器未配置MongoOperations。

在使用之前，您需要在阅读器上设置一个。