领域ORM:如何处理地图? [英] Realm ORM: how to deal with Maps?

问题描述

我正在创建一个Android应用，并且需要保持Map<String,MyClass>. 我刚刚开始使用领域ORM ，因为它支持一对一和一对多，枚举和列表.我还找到了字符串列表的解决方法(即，我必须创建一个封装字符串的StringWrapper类. 但是，根据文档，我知道没有像RealmMap这样的简单方法用于列表. 因此，我正在寻找保留地图的最佳方法. 我当前的想法是用封装了String(以前的映射键)和MyClass的对象KeyValueObject列表代替我的地图.与 Map.Entry 相似. 出于技术原因，是否还有其他不需要我重新设计域模型的解决方案?

I am creating an Android app and I need to persist a Map<String,MyClass>. I've just started to use Realm ORM, as it supports one-to-one and one-to-many, enumerations and lists. I also found a workaround for lists of strings (i.e. I have to create a StringWrapper class encapsulating a string. However, from the documentation I understand there is no easy way like RealmMap, as it happens for lists. So, I'm looking for the best way to persist a map. My current idea is to replace my map with a list of objects KeyValueObject encapsulating a String (the former map key) and a MyClass. Similarly to Map.Entry. Is there any other solution that does not need me to rework the domain model for technology reasons?

推荐答案

您注意到，Realm尚不支持地图:

As you notice, Realm doesn't yet support maps: https://github.com/realm/realm-java/issues/759

您可以使用模型类:

class MyData extends RealmObject {
    private RealmList<MyMapEntry> myMap;
}

class MyMapEntry extends RealmObject {
    private String key;
    private MyClass value;
}

假设您有一个名为myData的MyData对象，并且希望获取与myKey关联的值，则查询MyClass myClass = myData.getMyMap().where().equalTo("key", myKey).firstFirst()可能会有用.

Say you have a MyData object called myData and you wish to fetch the value associated with myKey, the query MyClass myClass = myData.getMyMap().where().equalTo("key", myKey).firstFirst() might be useful.

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