我使用的是greendao 3.2,制作实体和数据库。一切都很好。但我在创建Id属性时遇到了问题,该属性必须为Auto increment。我知道如何在SQL中做到这一点,但是使用greendao会给我带来更多的困难。
我已经声明我的实体是正常的。让我给你举个例子。
@Entity
public class User {
// this will make your id autoincremented
@org.greenrobot.greendao.annotation.Id (autoincrement = true)
private Long Id;
private String name;
@Generated(hash = 690585871)
public User(Long Id, String name) {
this.Id = Id;
this.name = name;
}
@Generated(hash = 586692638)
public User() {
}
public Long getId() {
return this.Id;
}
public void setId(Long Id) {
this.Id = Id;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
}
并插入像这样的值
user = new User();
user.setName("Hello Green Dao");
Long id = userDao.insertOrReplace(user);
但它的记录一次又一次地重叠,Id为0。它没有像预期的那样工作。
请告诉我原因是什么。我也尝试过使用Insert,但它显示了相同的结果。请帮帮我,我被困住了。
发布于 2018-02-26 15:48:17
我已经使用了它,如下所示,它工作得很好。
@Entity(nameInDb = "cities")
public class City {
@Id(autoincrement = true)
private Long id;
....
}
唯一的区别是你使用了Id
,也许和大写的I
一起使用会使它成为保留字,从而导致这个问题。或者,您应该将上面的注释简要介绍给@Id
,而不是完整的包路径。我知道这听起来很奇怪,但值得一试。
发布于 2019-06-25 08:56:56
使用Long而不是long。这对我来说很有效
发布于 2018-02-26 15:53:50
我认为你错过了对这个功能的检查。请检查刀
public class UserDao extends AbstractDao<User, Long> {
public static final String TABLENAME = "USER";
/**
* Properties of entity User.<br/>
* Can be used for QueryBuilder and for referencing column names.
*/
public static class Properties {
public final static Property Id = new Property(0, Long.class, "Id", true, "_id");
public final static Property Name = new Property(1, String.class, "name", false, "NAME");
}
public UserDao(DaoConfig config) {
super(config);
}
public UserDao(DaoConfig config, DaoSession daoSession) {
super(config, daoSession);
}
/** Creates the underlying database table. */
public static void createTable(Database db, boolean ifNotExists) {
String constraint = ifNotExists? "IF NOT EXISTS ": "";
db.execSQL("CREATE TABLE " + constraint + "\"USER\" (" + //
"\"_id\" INTEGER PRIMARY KEY AUTOINCREMENT ," + // 0: Id
"\"NAME\" TEXT);"); // 1: name
}
/** Drops the underlying database table. */
public static void dropTable(Database db, boolean ifExists) {
String sql = "DROP TABLE " + (ifExists ? "IF EXISTS " : "") + "\"USER\"";
db.execSQL(sql);
}
@Override
protected final void bindValues(DatabaseStatement stmt, User entity) {
stmt.clearBindings();
Long Id = entity.getId();
if (Id != null) {
stmt.bindLong(1, Id);
}
String name = entity.getName();
if (name != null) {
stmt.bindString(2, name);
}
}
@Override
protected final void bindValues(SQLiteStatement stmt, User entity) {
stmt.clearBindings();
Long Id = entity.getId();
if (Id != null) {
stmt.bindLong(1, Id);
}
String name = entity.getName();
if (name != null) {
stmt.bindString(2, name);
}
}
@Override
public Long readKey(Cursor cursor, int offset) {
return cursor.isNull(offset + 0) ? null : cursor.getLong(offset + 0);
}
@Override
public User readEntity(Cursor cursor, int offset) {
User entity = new User( //
cursor.isNull(offset + 0) ? null : cursor.getLong(offset + 0), // Id
cursor.isNull(offset + 1) ? null : cursor.getString(offset + 1) // name
);
return entity;
}
@Override
public void readEntity(Cursor cursor, User entity, int offset) {
entity.setId(cursor.isNull(offset + 0) ? null : cursor.getLong(offset + 0));
entity.setName(cursor.isNull(offset + 1) ? null : cursor.getString(offset + 1));
}
@Override
protected final Long updateKeyAfterInsert(User entity, long rowId) {
entity.setId(rowId);
return rowId;
}
@Override
public Long getKey(User entity) {
if(entity != null) {
return entity.getId();
} else {
return null;
}
}
@Override
public boolean hasKey(User entity) {
return entity.getId() != null;
}
@Override
protected final boolean isEntityUpdateable() {
return true;
}
}
整个项目都被称为here。我想你需要保留一些像这样的支票。在UserDao中。
https://stackoverflow.com/questions/48983527
复制相似问题