将“数组列中的值”转换为MongoDB查询到MongoDB Spring数据代码

Question

如何使用Java MongoDB Spring Data驱动程序将以下MongoDB查询转换为基于Java的查询？

db.User.aggregate([
{ $match : { $expr: { $in: [ "ADMIN", "$roles" ] } } },
{ $sort : { "createdAt": 1 } },
{ $limit : 1 }
])

我在Kotlin中尝试过的解决方案，我认为这是错误的（我不知道如何在用户文档中指定“角色”为字段。

fun queryFirstAdmin(): User? {

    val matchRolesOpt = Aggregation.match(Criteria.where("ADMIN").`in`("roles"))
    val sortOpt = Aggregation.sort(Sort.Direction.ASC, "createdAt")
    val limitOpt = Aggregation.limit(1)
    var ops: MutableList<AggregationOperation> = mutableListOf()
    ops.add(matchRolesOpt)
    ops.add(sortOpt)
    ops.add(limitOpt)
    var aggregation = Aggregation.newAggregation(*ops.toTypedArray())
    val aggregationResult = mongoTemplate.aggregate(aggregation, User::class.java, User::class.java)
    return aggregationResult.uniqueMappedResult
}

此解决方案有效，但不幸的是，它返回了用户文档的一部分（因为它已经解开）：

fun queryFirstAdmin(): User? {
    val unwindOpt = Aggregation.unwind("roles")
    val matchRolesOpt = Aggregation.match(Criteria.where("roles").`is`("ADMIN"))
    val sortOpt = Aggregation.sort(Sort.Direction.ASC, "createdAt")
    val limitOpt = Aggregation.limit(1)
    var ops: MutableList<AggregationOperation> = mutableListOf(unwindOpt, matchRolesOpt, sortOpt, limitOpt)
    var aggregation = Aggregation.newAggregation(*ops.toTypedArray())
    val aggregationResult = mongoTemplate.aggregate(aggregation, User::class.java, User::class.java)
    return aggregationResult.uniqueMappedResult
}

即如果返回的文档具有数组[“ ADMIN”]，但是原始文档的“角色”字段中具有[“ ADMIN”，“ USER]

我该如何解决？

Answer 1

<< [MongoDB Spring Data聚合的Java代码：

MongoOperations mongoOps = new MongoTemplate(MongoClients.create(), "test");
Aggregation agg = newAggregation(
        match(where("roles").is("ADMIN")),
        sort(ASC, "createdAt"),
        limit(1L)
);
AggregationResults<Document> results = mongoOps.aggregate(agg, "User", Document.class);
results.forEach(System.out::println);

注意：

聚合中的匹配阶段

{ $match : { $expr: { $in: [ "ADMIN", "$roles" ] } } }

可以替换成这个，结果是一样的：

{ $match : { roles: "ADMIN" } }

使用MongoDB Java Driver的相同查询：
Bson match = match(expr( Document.parse(" { $in: [ 'ADMIN', '$roles' ] } ")));
// -or- 
// Bson match = match(eq("roles", "ADMIN"));

List<Bson> pipeline = 
        Arrays.asList(match, sort(ascending("createdAt")), limit(1));

List<Document> results = new ArrayList<>();
collection.aggregate(pipeline).into(results); 

results.forEach(System.out::println);

Answer 2

fun queryFirstAdmin(): User? {

    val matchRolesOpt = Aggregation.match(Criteria.where("ADMIN").`in`("roles"))
    val sortOpt = Aggregation.sort(Sort.Direction.ASC, "createdAt")
    val limitOpt = Aggregation.limit(1)
    var ops: MutableList<AggregationOperation> = mutableListOf()
    ops.add(matchRolesOpt)
    ops.add(sortOpt)
    ops.add(limitOpt)
    var aggregation = Aggregation.newAggregation(*ops.toTypedArray())
    val aggregationResult = mongoTemplate.aggregate(aggregation, User::class.java, User::class.java)
    return aggregationResult.uniqueMappedResult
}

Answer 3

fun queryFirstAdmin(): User? {
    val unwindOpt = Aggregation.unwind("roles")
    val matchRolesOpt = Aggregation.match(Criteria.where("roles").`is`("ADMIN"))
    val sortOpt = Aggregation.sort(Sort.Direction.ASC, "createdAt")
    val limitOpt = Aggregation.limit(1)
    var ops: MutableList<AggregationOperation> = mutableListOf(unwindOpt, matchRolesOpt, sortOpt, limitOpt)
    var aggregation = Aggregation.newAggregation(*ops.toTypedArray())
    val aggregationResult = mongoTemplate.aggregate(aggregation, User::class.java, User::class.java)
    return aggregationResult.uniqueMappedResult
}

即如果返回的文档具有数组[“ ADMIN”]，但是原始文档的“角色”字段中具有[“ ADMIN”，“ USER]

我该如何解决？