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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package androidx.room.integration.testapp;
     18 
     19 import android.app.Application;
     20 
     21 import androidx.annotation.WorkerThread;
     22 import androidx.arch.core.executor.ArchTaskExecutor;
     23 import androidx.lifecycle.AndroidViewModel;
     24 import androidx.lifecycle.LiveData;
     25 import androidx.paging.DataSource;
     26 import androidx.paging.LivePagedListBuilder;
     27 import androidx.paging.PagedList;
     28 import androidx.paging.RxPagedListBuilder;
     29 import androidx.room.Room;
     30 import androidx.room.integration.testapp.database.Customer;
     31 import androidx.room.integration.testapp.database.LastNameAscCustomerDataSource;
     32 import androidx.room.integration.testapp.database.SampleDatabase;
     33 
     34 import java.util.UUID;
     35 
     36 import io.reactivex.BackpressureStrategy;
     37 import io.reactivex.Flowable;
     38 
     39 /**
     40  * Sample database-backed view model of Customers
     41  */
     42 public class CustomerViewModel extends AndroidViewModel {
     43     private SampleDatabase mDatabase;
     44     private LiveData<PagedList<Customer>> mLiveCustomerList;
     45 
     46     public CustomerViewModel(Application application) {
     47         super(application);
     48         createDb();
     49     }
     50 
     51     private void createDb() {
     52         mDatabase = Room.databaseBuilder(this.getApplication(),
     53                 SampleDatabase.class, "customerDatabase").build();
     54 
     55         ArchTaskExecutor.getInstance().executeOnDiskIO(() -> {
     56             // fill with some simple data
     57             int customerCount = mDatabase.getCustomerDao().countCustomers();
     58             if (customerCount == 0) {
     59                 Customer[] initialCustomers = new Customer[10];
     60                 for (int i = 0; i < 10; i++) {
     61                     initialCustomers[i] = createCustomer();
     62                 }
     63                 mDatabase.getCustomerDao().insertAll(initialCustomers);
     64             }
     65 
     66         });
     67     }
     68 
     69     @WorkerThread
     70     private Customer createCustomer() {
     71         Customer customer = new Customer();
     72         customer.setName(UUID.randomUUID().toString());
     73         customer.setLastName(UUID.randomUUID().toString());
     74         return customer;
     75     }
     76 
     77     void insertCustomer() {
     78         ArchTaskExecutor.getInstance().executeOnDiskIO(
     79                 () -> mDatabase.getCustomerDao().insert(createCustomer()));
     80     }
     81 
     82     void clearAllCustomers() {
     83         ArchTaskExecutor.getInstance().executeOnDiskIO(
     84                 () -> mDatabase.getCustomerDao().removeAll());
     85     }
     86 
     87     private static <K> LiveData<PagedList<Customer>> getLivePagedList(
     88             K initialLoadKey, DataSource.Factory<K, Customer> dataSourceFactory) {
     89         PagedList.Config config = new PagedList.Config.Builder()
     90                 .setPageSize(10)
     91                 .setEnablePlaceholders(false)
     92                 .build();
     93         return new LivePagedListBuilder<>(dataSourceFactory, config)
     94                 .setInitialLoadKey(initialLoadKey)
     95                 .build();
     96     }
     97 
     98     private static <K> Flowable<PagedList<Customer>> getPagedListFlowable(
     99             DataSource.Factory<K, Customer> dataSourceFactory) {
    100         PagedList.Config config = new PagedList.Config.Builder()
    101                 .setPageSize(10)
    102                 .setEnablePlaceholders(false)
    103                 .build();
    104         return new RxPagedListBuilder<>(dataSourceFactory, config)
    105                 .buildFlowable(BackpressureStrategy.LATEST);
    106     }
    107 
    108     Flowable<PagedList<Customer>> getPagedListFlowable() {
    109         return getPagedListFlowable(mDatabase.getCustomerDao().loadPagedAgeOrder());
    110     }
    111 
    112     LiveData<PagedList<Customer>> getLivePagedList(int position) {
    113         if (mLiveCustomerList == null) {
    114             mLiveCustomerList =
    115                     getLivePagedList(position, mDatabase.getCustomerDao().loadPagedAgeOrder());
    116         }
    117         return mLiveCustomerList;
    118     }
    119 
    120     LiveData<PagedList<Customer>> getLivePagedList(String key) {
    121         if (mLiveCustomerList == null) {
    122             mLiveCustomerList =
    123                     getLivePagedList(key, LastNameAscCustomerDataSource.factory(mDatabase));
    124         }
    125         return mLiveCustomerList;
    126     }
    127 }
    128