如何编写更新嵌入式文档的查询

Question

我刚开始使用Spring data mongob，但我只是被卡住了，如何使用mongo存储库编写基于json的嵌入式文档查询。

我的数据库看起来像

"_id" : ObjectId("5565ad670cf25cbd975ab2d9"),
    "_class" : "com.samepinch.domain.metadata.Metadata",
    "preferenceType" : "shopping",
    "subtypes" : [
        {
            "_id" : ObjectId("5565ad670cf25cbd975ab2d2"),
            "subType" : "veg",
            "preferencePoint" : 0
        },
        {
            "_id" : null,
            "subType" : "nonveg",
            "preferencePoint" : 0
        }
    ],
    "createdDate" : ISODate("2015-05-27T11:41:27.357Z"),
    "updatedDate" : ISODate("2015-05-27T11:41:27.357Z")

我想更新基于顶级文档id的子类型，我必须更新具有id 5565ad670cf25cbd975ab2d2的子类型的首选项，如何为此编写查询？

Answer 1

来自@Query java doc org。springframework。数据mongodb。存储库。查询

注释直接在存储库方法上声明查找器查询。这两个属性都允许使用占位符符号？0, ?1等等。

以下是可以传递给注释的所有属性（如下所示）

从定义来看，您似乎只能读取、筛选特定字段、执行count（）或删除与查询匹配的域对象。我没有看到任何关于更新的信息。

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Documented
@QueryAnnotation
public @interface Query {

    /**
     * Takes a MongoDB JSON string to define the actual query to be executed. This one will take precendece over the
     * method name then.
     * 
     * @return
     */
    String value() default "";

    /**
     * Defines the fields that should be returned for the given query. Note that only these fields will make it into the
     * domain object returned.
     * 
     * @return
     */
    String fields() default "";

    /**
     * Returns whether the query defined should be executed as count projection.
     * 
     * @since 1.3
     * @return
     */
    boolean count() default false;

    /**
     * Returns whether the query should delete matching documents.
     * 
     * @since 1.5
     * @return
     */
    boolean delete() default false;

Answer 2

您应该将$projection与$elemMatch查询一起使用，如下所示：

db.collectionName.update({"_id" : ObjectId("5565ad670cf25cbd975ab2d9"),
"subtypes":{"$elemMatch":{"_id":ObjectId("5565ad670cf25cbd975ab2d2")}}},
{"$set":{"subtypes.$.preferencePoint":1}})

及其等效的java代码为：

BasicDBObject eleMatch = new BasicDBObject();
eleMatch.put("_id", new ObjectId("5565ad670cf25cbd975ab2d2"));
BasicDBObject elemMatchQuery = new BasicDBObject();
elemMatchQuery.put("$elemMatch", eleMatch);
BasicDBObject query = new BasicDBObject();
query.put("_id", new ObjectId("5565ad670cf25cbd975ab2d9"));
query.put("subtypes", elemMatchQuery);
BasicDBObject set = new BasicDBObject();
set.put("subtypes.$.preferencePoint", 1);
BasicDBObject update = new BasicDBObject();
update.put("$set", set);
DBCollection dbcoll = mongoTemplate.getCollection("collectionName");
DBObject object = dbcoll.update(query, update);