Mongo查询不适用于嵌入式文档

Question

db.getCollection('employee').find({"departments.status" : "A"})

{
    "firstName" : "Sichita",
    "lastName" : "Vinchurkar",
    "email" : "[e-mail]",
    "departments" : [ 
        {
            "deptName" : "IT Support",
            .......
            .......
            "status" : "A"
        }, 
        {
            "deptName" : "Mobile Development",
            .......
            .......
            "status" : "I"
        }, 
        {
            "deptName" : "Advisory Dept",
            .......
            .......
            "status" : "A"
        },
        .........
        ..........
        .........
}

Answer 1

解决方案是使用MongoDB Spring Data(v2.2.6)MongoTemplateAPI的聚合。使用find查询（因此使用聚合的$filter数组运算符）无法检索基于条件的特定数组元素。

MongoOperations mongoOps = new MongoTemplate(MongoClients.create(), "test");
Aggregation agg = newAggregation(
    match(Criteria.where("departments.status").is("A")),
    project()
        .and(filter("departments")
                .as("dept")
                .by(Eq.valueOf("dept.status").equalToValue("A")))
    .as("departments")
);

AggregationResults<Document> results = mongoOps.aggregate(agg, "collection", Document.class);
results.forEach(doc -> System.out.println(doc.toJson()));

[编辑与添加]

包括代码中使用的类和接口的import语句：

import org.springframework.data.mongodb.core.MongoOperations;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.aggregation.Aggregation;
import org.springframework.data.mongodb.core.aggregation.AggregationResults;

import static org.springframework.data.mongodb.core.aggregation.Aggregation.newAggregation;
import static org.springframework.data.mongodb.core.aggregation.Aggregation.match;
import static org.springframework.data.mongodb.core.aggregation.Aggregation.project;
import static org.springframework.data.mongodb.core.aggregation.ArrayOperators.Filter.filter;
import static org.springframework.data.mongodb.core.aggregation.ComparisonOperators.Eq;