DialogFragment 中的 ViewModel

Question

我正在尝试更改此 class 以处理我的房间查询

@Query("select * from customer_contacts where serverCustomerId = :id and contactName like '%' || :name || '%'")
fun fetchCustomerContactsByName(id:Int, name:String): LiveData<List<CustomerContact>>

和我的视图模型

class CustomerContactVM : ViewModel() {
var customers: LiveData<List<CustomerContact>> = MutableLiveData<List<CustomerContact>>()

fun getCustomerContacts(id: Int, name: String) {
    customers = CustomerContactDao().fetchCustomerContactsByName(id, name)
}
}

我不明白如何在对话框片段中创建视图模型，因为我不断遇到无法解决尝试 ViewModelProviders.of(this).get(CustomerContactVM.class)

的错误

public class CustomerContactListFragment extends DialogFragment {

private CustomerContactVM customerContactVM;

@Override
public void onStart() {
    super.onStart();
    //setEmptyText("No Items");
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    if (savedInstanceState != null) { mCustomer = savedInstanceState.getString(ARG_CUSTOMER);
        if (savedInstanceState.getString(ARG_QUERY) != null) {
            mQuery = savedInstanceState.getString(ARG_QUERY);
        }
    }

    GlobalState globalState = (GlobalState) getActivity().getApplication();
   // mState.addScreenLog("CustomerContactListFragment");

    return inflater.inflate(R.layout.fragment_catalogue_items, container, false);
}
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
}


@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
}

@Override
public void onDetach() {
    dbHelper.close();
    super.onDetach();
}


}

Answer 1

ViewModelProviders.of (this) 已弃用。所以你应该使用最新版本的生命周期组件。

     implementation "androidx.lifecycle:lifecycle-extensions:2.2.0-rc03"

     //for kotlin
     implementation "group: 'androidx.lifecycle', name:'lifecycle-viewmodel-ktx', version:2.2.0-rc03"
     kapt "androidx.lifecycle:lifecycle-compiler:2.2.0-rc03"

ViewModel 初始化（Java）：

private CustomerContactVM customerContactVM;

@Override
protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);

   customerContactVM = ViewModelProvider(this).get(CustomerContactVM.class);
   // Other setup code below...
}

ViewModel 初始化 (Kotlin)：

var customerContactVM:CustomerContactVM? = null

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    customerContactVM = ViewModelProvider(this).get(CustomerContactVM::class.java)
    // Other setup code below...
    }

Answer 2

如果您将 DialogFragment 用作 activity 中的对话框并希望引用此 activity 的 ViewModel（而不是为 DialogFragment 创建一个新的），您应该使用：

private CustomViewModel viewModel;

@Override
protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);

   viewModel = ViewModelProvider(requireActivity()).get(CustomViewModel .class);
   // Other setup code below...
}

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