java ORMLite Android 中的一对多关系
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One-To-Many relationship in ORMLite Android
提问by Rockin
How do I implement one-many relationship in ORMLite Android?
如何在 ORMLite Android 中实现一对多关系？
please find the example
请找出例子
public class A {
private String name;
@DatabaseField (foreign = true, foreignAutoRefresh = true, columnName = "A")
private B b;
@DatabaseField(columnName = "author")
private String authorName;
}
public class B {
@DatabaseField(generatedId = true, columnName = "id")
private long id;
@DatabaseField(columnName = "name")
private String name;
@ForeignCollectionField
Collection<A> aees;
}
B has collection of A. I am calling dao.create(b);
B 有 A 的集合。我正在打电话 dao.create(b);
Now i create dao of b, since b has all the data. But the table B has only created with data, A is never created. Kindly could some one help?
现在我创建了 b 的 dao，因为 b 拥有所有数据。但是表 B 只创建了数据，A 从未创建过。请有人帮忙吗？
回答by Gray
Now i create dao of b, since b has all the data. But the table B has only created with data, A is never created. Kindly could some one help?
现在我创建了 b 的 dao，因为 b 拥有所有数据。但是表 B 只创建了数据，A 从未创建过。请有人帮忙吗？
Right. You need to create the Aitems using:
对。您需要A使用以下方法创建项目：
for (A a : b.aees) {
aDao.create(a);
}
ORMLite does not automatically create those for you.
ORMLite 不会自动为您创建那些。
You might take a look a the source code of the foreign-collection example program.
你可以看一下foreign-collection示例程序的源代码。
回答by bogdan
You have to override the DAO of the B class, so when an object B is created or updated, the objects in the collection to be also updated.
你必须重写 B 类的 DAO，所以当一个对象 B 被创建或更新时，集合中的对象也被更新。
Take a look at this question: Collections in ORMLite.
看看这个问题：ORMLite 中的集合。
回答by Yasir Ali
i was facing the same problem. My json was like:
我面临同样的问题。我的 json 是这样的：
{
"parent":{
"name":"ABC",
"children":[
{"childName":"1"},
{"childName":"2"},
{"childName":"3"}
]
}
}
i resolved the issue like this:
我解决了这样的问题：
Parent parent = new Parent();
parent.setName("ABC");
while(get children one by one from json data)
{
childrenArray.add(new Child(its Name));
}
parentDAO.create(parent);
for(Child child : childrenArray)
{
child.setParent(parent);
childDAO.create(child);
}
