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java-Realm返回对象的空列表
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我想从农民对象中获取CropDataList.当我获取Farmer Object时,它不为null,但与Farmer Object相关联的cropData列表返回空.我可以通过Stetho看到数据库条目,并且列表中有一个条目.这是我的代码.
public class Farmer extends RealmObject {
@PrimaryKey
private String id;
private RealmList<CropData> cropData;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public RealmList<CropData> getCropData() {
return cropData;
}
public void setCropData(RealmList<CropData> cropData) {
this.cropData = cropData;
}
public static class Constants {
public static final String FARMER_ID = "id";
}
}
这是我的CropData.class
public class CropData extends RealmObject {
private String cropName;
private String crop;
private Float cropAcres;
private Float cropYield;
private Float cropPrice;
public String getCropName() {
return cropName;
}
public void setCropName(String cropName) {
this.cropName = cropName;
}
public String getCrop() {
return crop;
}
public void setCrop(String crop) {
this.crop = crop;
}
public Float getCropAcres() {
return cropAcres;
}
public void setCropAcres(Float cropAcres) {
this.cropAcres = cropAcres;
}
public Float getCropYield() {
return cropYield;
}
public void setCropYield(Float cropYield) {
this.cropYield = cropYield;
}
public Float getCropPrice() {
return cropPrice;
}
public void setCropPrice(Float cropPrice) {
this.cropPrice = cropPrice;
}
}
当我尝试通过以下方式获取列表时,该列表为空：
HashMap<String, String> credentials = QueryUtils.getCredentials( realm );
Farmer farmer = realm.where( Farmer.class ).equalTo( Farmer.Constants.FARMER_ID, credentials.get( "farmerId" ) ).findFirst();
// this farmer is not null, but associated cropData is empty...
if (farmer != null) {
RealmList<CropData> farmerCropData = farmer.getCropData();
**// this list is empty...**
Log.d( TAG, "getCropList: " + GsonUtils.toGson( farmerCropData ) );
这就是我插入cropData的方式.
public void updateCrop(String authToken, String farmerId, CropDataUpdateRequest cropDataUpdateRequest, Context context) {
EndPoints.updateCrop( authToken, farmerId, cropDataUpdateRequest, new Callback<BasicResponse>() {
@Override
public void onResponse(@NonNull Call<BasicResponse> call, @NotNull Response<BasicResponse> response) {
if (response.isSuccessful()) {
BasicResponse basicResponse = response.body();
assert basicResponse != null;
ErrorCode errorCode = basicResponse.getErrorCode();
if (!NetworkErrorHandlingUtils.ErrorCheck( errorCode )) {
UpdateCropResponse updateCropResponse = GsonUtils.fromGson( basicResponse.getResponse(), UpdateCropResponse.class );
try (Realm realm = Realm.getDefaultInstance()) {
// update verification Response...
realm.executeTransactionAsync( realm1 -> realm1.insertOrUpdate( updateCropResponse.getUpdatedCrop() ) );
GetComparisonSheetRequest getComparisonSheetRequest = new GetComparisonSheetRequest();
CropData cropData = updateCropResponse.getUpdatedCrop().get( 0 );
if (cropData != null) {
getComparisonSheetRequest.setCrop( Crop.valueOf( cropData.getCrop() ) );
}
getIncomeComparisonSheet( authToken, farmerId, getComparisonSheetRequest, context );
getYieldComparisonSheet( authToken, farmerId, getComparisonSheetRequest, context );
getRecommendation( authToken, farmerId, context );
IntentUtils.PassIntent( context, HomeScreenActivity.class );
((Activity) context).finish();
}
} else {
// show error dialog here..., the error could be from one of the Error Code...
}
}
}
@Override
public void onFailure(@NonNull Call<BasicResponse> call, @NotNull Throwable t) {
// show UI for API Failure...
if (t instanceof NoConnectivityException) {
// This is where it throws No Internet connectivity error...
// show some UI here, sefu...
IntentUtils.PassIntent( context, NetworkErrorActivity.class );
}
// there's some other error, not network connectivity issue...
else {
}
}
} );
}
解决方法:
好的,所以我找到了答案,我将代码更改如下.我正在获取列表,然后清除它,然后将新数据添加到该列表中并更新我的农夫对象.
RealmList<CropData> cropDataRealmList = new RealmList<>();
cropDataRealmList.addAll( updateCropResponse.getUpdatedCrop() );
Realm realm = Realm.getDefaultInstance();
realm.beginTransaction();
Farmer farmer = realm.where( Farmer.class ).equalTo( Farmer.Constants.FARMER_ID, farmerId ).findFirst();
if (farmer != null) {
RealmList<CropData> farmerCropData = farmer.getCropData();
farmerCropData.clear();
farmerCropData.addAll( cropDataRealmList );
CropData cropData = updateCropResponse.getUpdatedCrop().get( 0 );
if (cropData != null) {
GetComparisonSheetRequest getComparisonSheetRequest = new GetComparisonSheetRequest();
getComparisonSheetRequest.setCrop( Crop.valueOf( cropData.getCrop() ) );
getIncomeComparisonSheet( authToken, farmerId, getComparisonSheetRequest, context );
getYieldComparisonSheet( authToken, farmerId, getComparisonSheetRequest, context );
getRecommendation( authToken, farmerId, context );
}
realm.copyToRealmOrUpdate( farmer );
realm.commitTransaction();
realm.close();
IntentUtils.PassIntent( context, HomeScreenActivity.class );
((Activity) context).finish();
}
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