bucket:按照范围分组
官网原生代码:
db.artwork.aggregate( [
{
$bucket: {
groupBy: "$price",
boundaries: [ 0, 200, 400 ],
default: "Other",
output: {
"count": { $sum: 1 },
"titles" : { $push: "$title" }
}
}
}
] )
字段解释:
groupBy:分组的字段
boundaries:分组的范围
default:最后一个组的名称
output:输出的其它内容
Spring data mongodb:
实体类:role
@Document(collection = "role")
@TypeAlias("role")
public class Role extends Contact {
public Role(String name, int age) {
this.name = name;
this.age = age;
}
private String name;
private int age;
插入数据:
mongoTemplate.save(new Role("zhang1",5));
mongoTemplate.save(new Role("zhang2",6));
mongoTemplate.save(new Role("zhang3",12));
mongoTemplate.save(new Role("zhang4",14));
mongoTemplate.save(new Role("zhang5",23));
测试bucket:
TypedAggregation<Role> agg = Aggregation.newAggregation(Role.class,Aggregation.bucket("age")
.withBoundaries(0,10,20)
.withDefaultBucket("other1")
.andOutput("name").count().as("count")
.andOutput("age").sum().as("sum")
.andOutput("name").push().as("names"));
AggregationResults<Document> result = mongoTemplate.aggregate(agg,Document.class);
result.getMappedResults().forEach(document -> System.out.println(document));
结果:
Document{{_id=0, count=2, sum=11, names=[zhang1, zhang2]}}
Document{{_id=10, count=2, sum=26, names=[zhang3, zhang4]}}
Document{{_id=other1, count=1, sum=23, names=[zhang5]}}
注意:
1 输出count时,andOutput("name")里的name是可以任意填,因为数量是和字段无关的
2 push 是将各个分组的某个字段(name)的所有值都输出