从 kotlin 中的 Json 数组/数据模型类创建房间数据库“实体”类的问题

Question

我是房间数据库的新手。我遇到了从 JsonArray 下面创建实体类的问题。

您能否帮助从以下文件创建实体类：

[
{
"id":1,
"name":"Leanne Graham",
"username":"Bret",
"email":"Sincere@april.biz",
"address":{
"street":"Kulas Light",
"suite":"Apt. 556",
"city":"Gwenborough",
"zipcode":"92998-3874",
"geo":{
"lat":"-37.3159",
"lng":"81.1496"
}
},
"phone":"1-770-736-8031 x56442",
"website":"hildegard.org",
"company":{
"name":"Romaguera-Crona",
"catchPhrase":"Multi-layered client-server neural-net",
"bs":"harness real-time e-markets"
}
},
{
"id":2,
"name":"Ervin Howell",
"username":"Antonette",
"email":"Shanna@melissa.tv",
"address":{
"street":"Victor Plains",
"suite":"Suite 879",
"city":"Wisokyburgh",
"zipcode":"90566-7771",
"geo":{
"lat":"-43.9509",
"lng":"-34.4618"
}
},
"phone":"010-692-6593 x09125",
"website":"anastasia.net",
"company":{}
}
]

和我的数据模型类如下

    data class MyModel (
    val id: Long,
    val name: String,
    val username: String,
    val email: String,
    val address: Address,
    val phone: String,
    val website: String,
    val company: Company
){

}
data class Address (
    val street: String,
    val suite: String,
    val city: String,
    val zipcode: String,
    val geo: Geo
)
data class Geo (
    val lat: String,
    val lng: String
)

data class Company (
    val name: String,
    val catchPhrase: String,
    val bs: String
)

我不知道我的数据模型类是否正确以及如何从我的数据模型或 Json 生成实体类响应

Answer 1

在您的情况下，您可能只有一个 @Entity -> User 和其他您可以用作 @Embeded 对象。

@Entity
data class User (
    @PrimaryKey(autoGenerate = true)
    var id: Long = 0,

    val name: String,
    val username: String,
    val email: String,
    @Embedded val address: Address,
    val phone: String,
    val website: String,
    @Embedded val company: Company
)

完整的源代码在这里：https://github.com/dautovicharis/sos_android/tree/q_68390737

在此处了解有关 Room DB 的更多信息：https://developer.android.com/training/data-storage/room

Answer 2

您可以安装 JSON TO Kotlin 类插件并使用它。为此：

1. 在 Android Studio 中选择文件 -> 设置

2. 搜索插件

3. 选择 Marketplace 并搜索“JSON TO Kotlin 类”。

安装插件后重启 Android Studio。现在您可以使用此插件将 JSON 转换为 Kotlin 类。为此，请按 Alt + k 或按照以下步骤操作：

1- 转到代码

2-选择生成

3- 从 json 中选择 Kotlin 数据类

现在粘贴 JSON 并在提供类名后单击生成按钮。对于您的 JSON，结果是：

data class MyModelItem(
    val address: Address,
    val company: Company,
    val email: String,
    val id: Int,
    val name: String,
    val phone: String,
    val username: String,
    val website: String
)

data class Address(
    val city: String,
    val geo: Geo,
    val street: String,
    val suite: String,
    val zipcode: String
)

class Company(
)

data class Geo(
    val lat: String,
    val lng: String
)

现在您可以创建如下所示的实体：

@Entity
data class MyModelEntity(
 @PrimaryKey(autoGenerate = true)
 val id: Int,
 val city: String,
 val lat: String,
 val lng: String,
 val street: String,
 val suite: String,
 val zipcode: String,
 val company: Company,
 val email: String,
 val name: String,
 val phone: String,
 val username: String,
 val website: String
) 

在您的 dao 中，您可以按如下方式插入数据：

@Insert(onConflict = OnConflictStrategy.IGNORE)
fun addToDatabase(model: MyModelEntity?): Long

最后，您可以在您的存储库中使用以下代码：

 fun insertToDatabase(myModelItem: MyModelItem) {
    val myModelEntity = MyModelEntity(
        city = myModelItem.address.city,
        lat = myModelItem.address.lat,
        lng = myModelItem.address.lng,
        street = myModelItem.address.street,
        suite = myModelItem.address.suite,
        zipcode = myModelItem.address.zipcode,
        company = myModelItem.company,
        email = myModelItem.email,
        name = myModelItem.name,
        phone = myModelItem.phone,
        username = myModelItem.username,
        website = myModelItem.website
    )
    dao.addToDatabase(myModelEntity)
}