Question

我有一个实体（Kotlin代码）：

@Entity(foreignKeys = arrayOf(ForeignKey(entity = Agent::class, parentColumns = arrayOf("guid"), childColumns = arrayOf("agentGuid"), onDelete = ForeignKey.CASCADE)))
data class Client (@PrimaryKey
                   var guid: String = "",
                   var name: String = "",
                   var email: String = "",
                   var phone: String = "",
                   var address: String = "",
                   var agentGuid: String = "")

以下是Dao Class：

@Dao
public interface ClientDao {
    @Query("SELECT * FROM Client where guid = :clientGUID LIMIT 1")
    Client getClient(String clientGUID);

    @Query("SELECT * FROM Client where agentGuid = :agentGUID")
    List<Client> getClients(String agentGUID);

    @Insert
    void insertClient(Client client);
}

以下是我正在执行插入操作的后台任务：

interface UpdateClientTaskResponseHandler {
    fun clientUpdated(client: Client)
    fun clientUpdateFailed()
}
data class ClientData(var client: Client, var documents: ArrayList<Document>)

class UpdateClientDataTask(val responseHandler: UpdateClientTaskResponseHandler): AsyncTask<ClientData, Void, Client?>() {
    override fun doInBackground(vararg params: ClientData?): Client? {
        params[0]?.let {
            val clientDao = MyApp.database!!.clientDao()
            //1: Check if client exists or not
            val client = clientDao.getClient(it.client.guid)
            if (client != null) {
                //TODO: to be handled
                // Update functionality
            } else {
                //2. Insert client
                clientDao.insertClient(it.client)

                //3. Insert all documents
                if (it.documents.size > 0) {
                    val documentDao = MyApp.database!!.documentDao()
                    documentDao.insertDocuments(it.documents)
                }

                return it.client
            }

            return null
        }
        return null
    }

    override fun onPostExecute(result: Client?) {
        result?.let {
            responseHandler.clientUpdated(it)
        } ?: responseHandler.clientUpdateFailed()
    }
}

我使用下面的代码插入实体：

public void confirmClient(View view) {
        // Creating client object
        Client client = new Client(clientGuid, name, email, phone, address, agentGuid);
        // Creating client data object
        ClientData clientData = new ClientData(client, documentsAdapter.documents);
        UpdateClientDataTask updateClientDataTask = new UpdateClientDataTask(this);
        updateClientDataTask.execute(clientData);
    }

成功后我调用下面的代码跳回ClientActivity：

@Override
    public void clientUpdated(@NotNull Client client) {
        Intent clientsActivity = new Intent(this,ClientActivity.class);
        clientsActivity.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP );
        clientsActivity.putExtra(IntentKeysKt.getShouldRefreshData(), true);
        startActivity(clientsActivity);
    }

我的问题是 - 当我在onResume()的{{1}}方法中触发选择查询时，它没有返回插入的实体。以下是代码：

ClientActivity

令人惊讶的是，在下次应用启动时，它会显示插入的记录。我无能为力，请指教我。

Answer 1

你应该使用;

Database.beginTransaction()。
Database.setTransactionSuccessful()。
Database.endTransaction()终于。

示例代码：

private static void insertData(AppDatabase db, List<ProductEntity> products, List<CommentEntity> comments) {
    db.beginTransaction();
    try {
        db.productDao().insertAll(products);
        db.commentDao().insertAll(comments);
        db.setTransactionSuccessful();
    } finally {
        db.endTransaction();
    }
}

Sample reference

Android - RoomDb - 在另一个活动

1 个答案: