Realm Android 嵌套查询 [英] Realm Android Nested Query

问题描述

鉴于以下类和关系，我需要一个 RealmResults <满足以下要求的模型 1 >:

Given the below classes and relationships, I need a RealmResults < Model1 > that satisfies the following requirements:

模型 1

int id
RealmList<Model2>

模型 2

int id
int model1Fk
int type
RealmList<Model3>

Model3

int model2Fk

我想查询所有 Model1 实体，对于特定的 Model2 相关实例类型，该 Model2 实例至少有一个 Model3 相关实例.

I want to query all the Model1 entities that, for a specific Model2 related instance type, that Model2 instance has at least one Model3 related instance.

在 SQL 中(尚未测试):

In SQL that would be (Haven't tested it):

select distinct model1.*
from Model1 model1 join Model2 model2 on model2.model1Fk = model1.id join Model3 model3 on model3.model2Fk = model2.id
where model2.type = 'Some Type'

推荐答案

你的文字描述和加入不匹配，但是如果你想找到所有带有Model2的Model1Some type的code>，你可以执行以下操作:

Your text description and join doesn't match, but if you want to find all Model1 with a Model2 of Some type, you can do the following:

realm.where(Model1.class).equalTo("model2List.type", "Some Type").findAll();

您可以在此处阅读有关链接查询的信息:https://realm.io/docs/java/latest/#link-queries.

You can read about link queries here: https://realm.io/docs/java/latest/#link-queries.

如果你想找到所有 Model1 至少有 1 个 Model2 并且至少有一个 Model3 有某个值，你可以执行以下操作:

If you want to find all Model1 which have at least 1 Model2 that also have at least one Model3 with some value, you can do the following:

realm.where(Model1.class).equalTo("model2List.Model3List.model2Fk", "some model2Fk value").findAll();

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