Android DBFlow 不保存对象答案

【问题标题】：Android DBFlow does not save objectsAndroid DBFlow 不保存对象
【发布时间】：2016-12-29 10:02:10
【问题描述】：

我有一个这样的数据库：

@Database(name = QuestionDatabase.NAME, version = QuestionDatabase.VERSION)
public class QuestionDatabase {

    public static final String NAME = "QuestionDatabase"; // we will add the .db extension

    public static final int VERSION = 1;
}

还有这样的表格：

@Table(database = QuestionDatabase.class)
public class Question extends BaseModel {
    @PrimaryKey
    public int localID;
    @Column
    public int Id;
    @Column
    public String Answer;
    @Column
    public String ImageURL;
    @Column
    public boolean IsFavorite;
    @Column
    public boolean IsSolved;
}

还有一个从服务器检索数据的异步任务：

public class QuestionRetriever extends AsyncTask<Integer, Void, Integer> {

    private Activity callerActivity;
    private QuestionAdapter questionsAdapter;
    private List<Question> callerQuestions;

    private Integer pageSize = 10;

    public QuestionRetriever(Activity callerActivity, QuestionAdapter questionsAdapter, List<Question> questions){
        this.callerActivity = callerActivity;
        this.questionsAdapter = questionsAdapter;
        this.callerQuestions = questions;
    }

    @Override
    protected Integer doInBackground(Integer... pageNumbers) {
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("http://192.168.1.33:313/")
                .addConverterFactory(GsonConverterFactory.create())
                .build();

        QuestionWebService service = retrofit.create(QuestionWebService.class);

        Call<List<Question>> call = service.getQuestionsPaged(pageNumbers[0].toString(), pageSize.toString());

        try {
            Response<List<Question>> excecuted = call.execute();
            List<Question> questions = excecuted.body();
            FastStoreModelTransaction
                    .insertBuilder(FlowManager.getModelAdapter(Question.class))
                    .addAll(questions)
                    .build();
            callerQuestions.addAll(questions);
            callerActivity.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    questionsAdapter.notifyDataSetChanged();
                }
            });

            //Get TotalQuestionCount if not yet
            if (((StatefulApplication) callerActivity.getApplication()).getQuestionCount() == -1){
                Call<Integer> call2 = service.getQuestionsSize();
                try {
                    ((StatefulApplication) callerActivity.getApplication()).setQuestionCount(call2.execute().body());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        catch (Exception e){
            e.printStackTrace();
        }

        return 1;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        //TODO: show loader
    }

    @Override
    protected void onPostExecute(Integer result) {
        super.onPostExecute(result);

        //TODO: hide loader
    }
}

正如您所见，在运行 FastStoreModelTransaction 之后，一切似乎都正常，并且没有任何问题发生。没有错误。

初始化工作是在启动屏幕活动中完成的，如下所示：

private void initializeEveryRun() {
        //Initializing DBFlow
        //DBFlow needs an instance of Context in order to use it for a few features such as reading from assets, content observing, and generating ContentProvider.
        //Initialize in your Application subclass. You can also initialize it from other Context but we always grab the Application Context (this is done only once).
        FlowManager.init(new FlowConfig.Builder(getApplicationContext()).build());
    }

对导致此问题的原因或尝试任何解决方案有任何想法吗？ TG。

【问题讨论】：

标签： android save dbflow

【解决方案1】：

我找到了答案！！！

正如您在模型中看到的，Id 是从服务器检索到的对象的标识符，LocalId 是存储在本地的自增标识符。这就是问题所在。我使用 Id 字段作为主键，并添加了一个名为 OnlineId 的字段作为服务器端标识符，现在一切正常。

这是一个错误还是我用错了？

TG。

【讨论】：

【解决方案2】：

这不是执行事务，只是创建事务。

正如你所看到的，这个测试DBFlow - FastModelTest.kt。

FastStoreModelTransaction .insertBuilder(FlowManager.getModelAdapter(Question.class)) .addAll(questions) .build();

您必须像这样执行您的交易：
FlowManager.getDatabase(QuestionDatabase.class).executeTransaction(<<YourTransaction>>);

否则，如果您已经拥有 DatabaseWrapper 实例，您可以使用<<YourTransaction>>.excute(<<YourDatabaseWrapper>>);。

【讨论】：