进行Projection.Projection时，Morphia java.util.Arrays$ArrayList不能强制转换为com.mongodb.DBObject

我试图把下面的聚合

db.getCollection("order").aggregate(
    [
        { 
            "$project" : {
                "_id" : -1.0, 
                "customerId" : "$customer.customerId", 
                "hasOrderInT0" : {
                    "$cond" : [
                        {
                            "$and" : [
                                {
                                    "$gte" : [
                                        "$date", 
                                        1577829600.0
                                    ]
                                }, 
                                {
                                    "$lte" : [
                                        "$date", 
                                        1580507999.0
                                    ]
                                }
                            ]
                        }, 
                        1, 
                        0
                    ]
                }
            }
        }
    ]
);

在Java应用程序中，我使用Morphia作为ORM。基本上，如果日期介于2个时间戳之间，它将在

hasOrderInT0

字段中输入1，否则输入0

long initialStart = 1577829600;
long initialEnd = 1580507999;

AggregationPipeline pipeline = databaseService.getConnection().createAggregation(Order.class)
                .project(
                        Projection.projection("_id", "-1"),
                        Projection.projection("customerId", "$customer.customerId"),
                        Projection.projection("hasOrderInT0",
                                Projection.expression(
                                        "$cond",
                                        Arrays.<Object>asList(
                                                new BasicDBObject(
                                                        "$and", Arrays.<Object>asList(
                                                        new BasicDBObject(
                                                                "$gte", Arrays.<Object>asList("$date", initialStart)
                                                        ),
                                                        new BasicDBObject(
                                                                "$lte", Arrays.<Object>asList("$date", initialEnd)
                                                        )
                                                )
                                                ),
                                                1,
                                                0
                                        )
                                )
                        )
                );

这是我第一次在Morphia中使用投影，我不知道这是否是在mongo控制台中实现命令的正确方法

---

注：

$project

只是一个更大聚合的管道，但这是一个有趣的部分，它给出了错误，因此为了演示，我对它进行了简化。

结果表明，没有必要将$cond的条件包装到

数组中。asList

。Projection.expression已接受任意数量的参数，因此工作代码为：

long initialStart = 1577829600;
long initialEnd = 1580507999;

AggregationPipeline pipeline = databaseService.getConnection().createAggregation(Order.class)
                .project(
                        Projection.projection("_id", "-1"),
                        Projection.projection("customerId", "$customer.customerId"),
                        Projection.projection("hasOrderInT0",
                                Projection.expression(
                                        "$cond",
                                            new BasicDBObject(
                                                    "$and", Arrays.<Object>asList(
                                                    new BasicDBObject(
                                                            "$gte", Arrays.<Object>asList("$date", initialStart)
                                                    ),
                                                    new BasicDBObject(
                                                            "$lte", Arrays.<Object>asList("$date", initialEnd)
                                                    )
                                            )
                                            ),
                                            1,
                                            0
                                )
                        )
                );

long initialStart=1577829600；
长initialEnd=1580507999；
AggregationPipeline=databaseService.getConnection（）.CreateAgregation（Order.class）
.项目(
投影。投影（“_id”，“-1”），
Projection.Projection（“customerId”，“$customer.customerId”），
Projection.Projection（“hasOrderInT0”，
投影表达式(
“$cond”，
新的基本对象(
“$and”，Arrays.asList(
新的基本对象(
“$gte”，数组.asList（“$date”，initialStart）
),
新的基本对象(
“$lte”，Arrays.asList（“$date”，initialEnd）
)
)
),
1.
0
)
)
);

BasicDBObject是第一个参数，1和0是第二个和第三个参数，Morphia wrapper将正确解释它们

long initialStart = 1577829600;
long initialEnd = 1580507999;

AggregationPipeline pipeline = databaseService.getConnection().createAggregation(Order.class)
                .project(
                        Projection.projection("_id", "-1"),
                        Projection.projection("customerId", "$customer.customerId"),
                        Projection.projection("hasOrderInT0",
                                Projection.expression(
                                        "$cond",
                                            new BasicDBObject(
                                                    "$and", Arrays.<Object>asList(
                                                    new BasicDBObject(
                                                            "$gte", Arrays.<Object>asList("$date", initialStart)
                                                    ),
                                                    new BasicDBObject(
                                                            "$lte", Arrays.<Object>asList("$date", initialEnd)
                                                    )
                                            )
                                            ),
                                            1,
                                            0
                                )
                        )
                );