mongoDB 关联查询_lookupoperation.localfield.foreignfield

mongoDB 关联查询

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相关类与接口

lookUpOperation

public class LookupOperation implements FieldsExposingAggregationOperation, InheritsFieldsAggregationOperation {
    private final Field from;
    private final Field localField;
    private final Field foreignField;
    private final ExposedField as;
 
**********
构造方法
 
    public LookupOperation(Field from, Field localField, Field foreignField, Field as) {
 
 
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常用方法
 
    public static LookupOperation.FromBuilder newLookup() {
        return new LookupOperation.LookupOperationBuilder();
    }
 
 
 
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内部类
 
    public static final class LookupOperationBuilder implements LookupOperation.FromBuilder, LookupOperation.LocalFieldBuilder, LookupOperation.ForeignFieldBuilder, LookupOperation.AsBuilder {
        @Nullable
        private Field from;
        @Nullable
        private Field localField;
        @Nullable
        private Field foreignField;
        @Nullable
        private ExposedField as;
 
        public LookupOperationBuilder() {
        }
 
        public static LookupOperation.FromBuilder newBuilder() {
            return new LookupOperation.LookupOperationBuilder();
        }
 
        public LookupOperation.LocalFieldBuilder from(String name) {
            Assert.hasText(name, "'From' must not be null or empty!");
            this.from = Fields.field(name);
            return this;
        }
 
        public LookupOperation as(String name) {
            Assert.hasText(name, "'As' must not be null or empty!");
            this.as = new ExposedField(Fields.field(name), true);
            return new LookupOperation(this.from, this.localField, this.foreignField, this.as);
        }
 
        public LookupOperation.AsBuilder foreignField(String name) {
            Assert.hasText(name, "'ForeignField' must not be null or empty!");
            this.foreignField = Fields.field(name);
            return this;
        }
 
        public LookupOperation.ForeignFieldBuilder localField(String name) {
            Assert.hasText(name, "'LocalField' must not be null or empty!");
            this.localField = Fields.field(name);
            return this;
        }
    }
 
**********
需要关联的集合
 
    public interface FromBuilder {
        LookupOperation.LocalFieldBuilder from(String var1);
    }
 
 
**********
本地集合的关联键
 
    public interface LocalFieldBuilder {
        LookupOperation.ForeignFieldBuilder localField(String var1);
    }
 
 
**********
需要关联集合对应的键
 
    public interface ForeignFieldBuilder {
        LookupOperation.AsBuilder foreignField(String var1);
    }
 
 
**********
给关联集合的查询结果取别名
 
    public interface AsBuilder {
        LookupOperation as(String var1);
    }
 
}

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示例

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controller 层

HelloController

@RestController
public class HelloController {
 
    @Autowired
    private MongoTemplate mongoTemplate;
 
    @RequestMapping("/save")
    public String save(){
        for(int i=0;i<100;i++){
            Student student=new Student();
            student.setId(i);
            student.setName("瓜田李下"+i);
            student.setAge(i%10+15);
            student.setSchoolId(i%3);
 
            mongoTemplate.save(student);
        }
 
        for (int i=0;i<3;i++){
            School school=new School();
            school.setId(i);
            school.setName("海贼王"+i);
 
            mongoTemplate.save(school);
        }
 
        return "success";
    }
 
    @RequestMapping("/get")
    public List<Map> get(){            //查询结果以Map形式返回
        LookupOperation lookupOperation=LookupOperation.newLookup()
                .from("school")
                .localField("schoolId")
                .foreignField("_id")
                .as("school");
 
        Aggregation aggregation=Aggregation.newAggregation(lookupOperation);
        AggregationResults<Map> results=mongoTemplate.aggregate(aggregation,"student",Map.class);
 
        return results.getMappedResults();
    }
 
    @RequestMapping("/get2")
    public List<StudentMap> get2(){    //自定义类接收查询结果
        LookupOperation lookupOperation=LookupOperation.newLookup()
                .from("school")
                .localField("schoolId")
                .foreignField("_id")
                .as("school");
 
        Aggregation aggregation=Aggregation.newAggregation(lookupOperation);
        AggregationResults results=mongoTemplate.aggregate(aggregation,"student",StudentMap.class);
 
        return results.getMappedResults();
    }
 
    @RequestMapping("/get3")
    public List<Map> get3(){        //查询结果以Map形式返回，分页排序
        LookupOperation lookupOperation=LookupOperation.newLookup()
                .from("school")
                .localField("schoolId")
                .foreignField("_id")
                .as("school");
 
        Aggregation aggregation=Aggregation.newAggregation(lookupOperation,Aggregation.skip(10L),Aggregation.limit(10L),Aggregation.sort(Sort.by("age").descending()));
        AggregationResults<Map> results=mongoTemplate.aggregate(aggregation,"student",Map.class);
 
        return results.getMappedResults();
    }
 
    @RequestMapping("/get4")
    public List<StudentMap> get4(){       //自定义类接收查询结果，分页排序
        LookupOperation lookupOperation=LookupOperation.newLookup()
                .from("school")
                .localField("schoolId")
                .foreignField("_id")
                .as("school");
 
        Aggregation aggregation=Aggregation.newAggregation(lookupOperation,Aggregation.skip(5L),Aggregation.limit(5L),Aggregation.sort(Sort.by("school").ascending()));
        AggregationResults results=mongoTemplate.aggregate(aggregation,"student",StudentMap.class);
 
        return results.getMappedResults();
    }
}

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使用测试

/get

/get2

/get3

/get4