MongoDB UpdateFirst方法的用法 [英] MongoDB UpdateFirst Method Usage

问题描述

我正在使用MongoTemplate的UpdateFirst()更新内部文档.但是更新操作失败.

I am using MongoTemplate's UpdateFirst() to update the inner document. But the update operation is failing.

我的Mongo收藏结构:

my Mongo Collection Structure:

{
"_id" : ObjectId("540dfaf9615a9bd62695b2ed"),
"_class" : "com.springpoc.model.Awards",
"brand" : [ 
    {
        "name" : "Brand1",
        "descr" : "Desc1"
    }
],
"name" : "Award1",
"narname" : "Nar1"

}

Java代码:

mongoTemplate.updateFirst(
query(where("name").is("Award1")), 
Update.update("brand.$.descr", "Desc2"),
Awards.class);  

奖励类结构

public class Awards {

private String id;
List<Brand> brand = new ArrayList<Brand>();
private String name;
private String narname;

品牌类别结构

public class Brand {
private String name;
private String descr;

有关如何将文档"Brand.Name"更新为新值的任何建议.

Any suggestions on how to update the document "Brand.Name" to new value.

推荐答案

如果要在更新部分中使用运算符$，则必须在查询部分中显式编写that array.因此，

If you want to use operator $ in update portion, you have to explicitly write that array in the query portion. So,

mongoTemplate.updateFirst(
query(where("name").is("Award1")), 
Update.update("brand.$.descr", "Desc2"),
Awards.class);

应该是

mongoTemplate.updateFirst(
query(where("name").is("Award1"))
.and("brand.name").is("Brand1"), // "brand" in "brand.name" is necessary, others according to your requirement
Update.update("brand.$.descr", "Desc2"),
Awards.class);

如果您知道元素在数组中的位置，则不必使用$，您可以尝试如下操作:

If you know the position of element in array, `$' is unnecessary, you can try like this:

mongoTemplate.updateFirst(
query(where("name").is("Award1")), 
Update.update("brand.0.descr", "Desc2"), // 0 is the index of element in array
Awards.class);

以相同的方式处理name字段.

Same way to handle name field.

这篇关于MongoDB UpdateFirst方法的用法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！