嘿谷歌有一个使用@Relation的例子
@Entity
public class Pet {
int userId;
String name;
// other fields
}
public class UserNameAndAllPets {
public int id;
public String name;
@Relation(parentColumn = "id", entityColumn = "userId")
public List<Pet> pets;
}
是否可以保存字符串列表而不为其创建额外的类。我想避免 JsonProperty 和房间实体之间的不一致
我们希望有类似的东西
public class UserNameAndAllPets {
@JsonProperty("id")
public int id;
@JsonProperty("name")
public String name;
@Relation(parentColumn = "id")
@JsonProperty("pets")
public List<String> pets;
}
因为我收到以下 Json:
{
"id" : "1",
"name" : "someName",
"pets": ["cat", "dog", "camel"]
}
有人知道解决办法吗?
EDIT:
现在我的示例代码看起来像但我有错误:错误:参数的类型必须是用@Entity注释的类或其集合/数组。
@JsonIgnoreProperties(ignoreUnknown=true)
@Entity(tableName = TABLE_NAME)
public class Item {
@Ignore public static final String TABLE_NAME = "itemTable";
@PrimaryKey(autoGenerate = true)
Long id;
@JsonProperty("supplierName")
String supplierName;
@JsonProperty("eventDescription")
String eventDescription;
@JsonProperty("eventDate")
@TypeConverters(StringListToGsonConverter.class)
Date date;
@JsonProperty("carServiceType")
@TypeConverters(StringListToGsonConverter.class)
List<String> types;
public ServiceHistoryItem(Long id, String supplierName, String eventDescription, Date date, List<String> types) {
this.id = id;
this.supplierName = supplierName;
this.eventDescription = eventDescription;
this.date = date;
this.types = types;
}
public static class StringListToGsonConverter{
@TypeConverter
public static List<String> restoreList(String listOfString){
return new Gson().fromJson(listOfString, new TypeToken<List<String>>() {}.getType());
}
@TypeConverter
public static String saveListOfString(List<String> listOfString){
return new Gson().toJson(listOfString);
}
@TypeConverter
public static Date fromTimestamp(Long value) {
return value == null ? null : new Date(value);
}
@TypeConverter
public static Long dateToTimestamp(Date date) {
return date == null ? null : date.getTime();
}
}
}
EDIT2
保存项目时出现新问题
Dao 无法插入我的实体列表,没有原因......但是错误:参数的类型必须是用@Entity注释的类或其集合/数组。
@Dao
interface ItemDao {
@Query("SELECT * FROM " + Item.TABLE_NAME)
fun getAll(): LiveData<List<Item>>
@Query("DELETE FROM " + Item.TABLE_NAME)
fun deleteAllServiceHistory()
@Insert(onConflict = OnConflictStrategy.REPLACE)
fun insertNewItem(item: Item)
@Insert(onConflict = OnConflictStrategy.REPLACE)
fun insertNewItems(itemList: List<Item>) // <--- Error
}
SOLUTION for Dao
如果你使用 Kotlin,你应该使用 ArrayList
@Insert(onConflict = OnConflictStrategy.REPLACE)
fun insertNewItems(itemList: ArrayList<Item>)