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[英]Update field in an entity with updatable=false returns the entity with the field with the new value
[英]Adding a new field to an entity
我创建了一个director
班
@Entity(tableName = "director")
public class Director {
@PrimaryKey(autoGenerate = true)
@ColumnInfo(name = "did")
public int id;
@ColumnInfo(name = "full_name")
@NonNull
public String fullName;
public Director(@NonNull String fullName) {
this.fullName = fullName;
}
}
我决定通过添加迁移方法并在类中添加一个字段来添加一个新列
@Entity(tableName = "director")
public class Director {
@PrimaryKey(autoGenerate = true)
@ColumnInfo(name = "did")
public int id;
@ColumnInfo(name = "full_name")
@NonNull
public String fullName;
@ColumnInfo(name = "age")
public int age;
public Director(@NonNull String fullName) {
this.fullName = fullName;
}
}
方法
static final Migration MIGRATION_1_2 = new Migration(1, 2) {
@Override
public void migrate(SupportSQLiteDatabase database) {
String query = "ALTER TABLE 'director' ADD COLUMN 'age' INTEGER ";
database.execSQL(query);
}
};
当我执行代码时出现此错误
Caused by: java.lang.IllegalStateException: Migration didn't properly handle
它说它预期
age=Column{name='year', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0, defaultValue='null'}},
并发现
age=Column{name='year', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=0, defaultValue='null'},
我可以看到问题出在“notnull”部分,但如何解决这个问题? 我希望它为空。
尝试将默认年龄值设置为 0
static final Migration MIGRATION_1_2 = new Migration(1, 2) {
@Override
public void migrate(SupportSQLiteDatabase database) {
database.execSQL(
"ALTER TABLE 'director' ADD COLUMN 'age' INTEGER NOT NULL DEFAULT 0"
);
}
};
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