spring-data-mongodb 聚合问题 - V2EX
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anthoy

spring-data-mongodb 聚合问题

  •  
  •   anthoy May 22, 2021 2313 views
    This topic created in 1801 days ago, the information mentioned may be changed or developed.

    我在 spring-data-mongodb 中使用聚合,目的是实现查询下面数据

    { "name":"test1", "receivedDate":"2021-05-18 00:00:52", } { "name":"test2", "receivedDate":"2021-05-18 00:00:52", } { "name":"test3", "receivedDate":"2021-05-18 00:00:52", } { "name":"test4", "receivedDate":"2021-05-18 00:00:52", } 

    目标是通过聚合查询出来结果如下:

    { "name":["test1","test2","test3","test4"], } 

    1

    目前使用方式是这样子

    GroupOperation group = Aggregation.group().push("name").as("name"); 

    查询结果

    [ { "_id": null, "name": [ "test1", "test2", "test3", "test4", "test4" ] } ] 

    2

    但我修改为使用动态添加的时候

     GroupOperation group = Aggregation.group(); for (int i = 0; i < params.length; i++) { group.push(params[i]).as(params[i]); } 

    发现查询的结果为

    [ { "_id": null } ] 

    感觉动态 push 哪里并没有生效,查询了挺多的资料好像也没有找到,感觉使用人挺少的

    • 有没有大佬知道应该怎么写的?
    • 或者还有别的方式实现
    • 或者自己遍历会不会比使用聚合这个更加好?
    3 replies    2021-05-24 12:05:15 +08:00
    zm8m93Q1e5otOC69
        1
    zm8m93Q1e5otOC69  
       May 22, 2021
    有啥好的教程吗?之前用 GridFS 传文件,网上教程各种方法过时,还是自己摸索的用 GridBucket 实现的
    acr0ss
        2
    acr0ss  
       May 23, 2021
    可以打印 query,或者断点查看 query,明确语句是否正确。
    FEINIAO233
        3
    FEINIAO233  
       May 24, 2021   1
    动态添加里 写成 group = group.push(params[i]).as(params[i]); 就好了,我看了一下源码,push 函数里新建了一个 GroupOperation 对象,不是在本来的对象上操作的。
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