How to DELETE data from FIREBASE database from Sketchware app?

If you have an app which displays data from firebase database in a custom ListView, and you want to delete data from it, then follow this method.

This method of deleting data is for apps which push data to firebase database on button click by using blocks as shown in image below,
retrieves data from firebase database, on Firebase DB onChildAdded event, by using blocks as shown in image below,

In order to delete data from this kind of app follow the steps given below.

1. Add a new String list str.

2. In the CustomView, add an ImageView imageview2 and set it's image to delete icon. On clicking this ImageView the item will get deleted.



3. In Firebase DB onChildAdded event, inside Firebase DB... get children to List Map... then block,
add the block
Add [childKey] to List String [str],
as shown in image below.

This will create a list of keys or children at the DatabaseReference 'Chat'.

4. In the event onBindCustomView add the block
When [imageview2] clicked,
Inside this use blocks to delete key at that position in FirebaseDB and delete data at that position in String list:
FirebaseDB Chat delete key [get at (position) of List String (str)],
delete at (position) of List str.

If the app is using Firebase Storage to store images and push the url of images to FirebaseDB using blocks as shown below,


Then to delete the image alongwith the message, in onBindCustomView, inside When imageview2 clicked, alongwith the blocks shown above, use following blocks:
If (ListMap [map1] contains at (position) key [image]) then,
FirebaseStorage [fstore] delete file url (get value at (position) key [image] of ListMap [map1])

5. Add a new event Firebase DB onChildRemoved and there add the blocks to retrieve data from Firebase to MapList and display it in ListView, as shown in image below.

6. Save and run the project. Wait for the app to load data from firebase database. After that if you click inageview2 at any position in the list, data at that position in database will get deleted.

Watch the video below:


Comments

  1. UnknownJanuary 10, 2018 at 12:37 AM

    Thank you.. so much...
    i hope more tutorials to come

    ReplyDelete
  2. Franco CalderazzoJanuary 11, 2018 at 3:45 PM

    Thanks! i leave a like!

    ReplyDelete
  3. UnknownJanuary 12, 2018 at 1:27 PM

    Thanks alot!

    ReplyDelete
  4. UnknownJanuary 13, 2018 at 10:48 PM

    Cara ini berhasil untuk menghapus tetapi untuk aplikasi saya yang terhapus malah list bagian yang paling atas/pertama

    ReplyDelete
  5. UnknownJanuary 13, 2018 at 10:48 PM

    This comment has been removed by the author.

    ReplyDelete
  6. UnknownJanuary 14, 2018 at 1:59 AM

    Hi, thanks for this website,
    Thus, when I try to implement this, I get an error compiling :
    Listview1Adapter cannot be resolved to a type.
    Where am I wrong?
    Thanks

    ReplyDelete
    Replies
    1. UnknownJanuary 14, 2018 at 2:29 AM

      My solution is here http://www.sketchwarehelp.com/2017/10/how-to-create-custom-listview-in.html

      Delete
  7. sanjeevJanuary 14, 2018 at 2:26 AM

    Maybe you have not added listview1 onBindCustomView event.

    ReplyDelete
    Replies
    1. UnknownJanuary 14, 2018 at 3:55 AM

      Thanks

      Delete
    2. UnknownFebruary 2, 2018 at 6:05 PM

      It didn't work for me please help with the code.

      Delete
    3. AnonymousAugust 7, 2020 at 10:36 PM

      Sir I have a doubt. If the user clears the data of the app then, the list string will be lost and we can't delete it anymore. Is there is an alternative way?

      Delete
  8. UnknownApril 20, 2018 at 12:28 PM

    How to save ,reterive and edit the data to firebase.simply, not in listview.means to say data is fixed in numbers(not unlimited)

    ReplyDelete
  9. sanjeevApril 20, 2018 at 12:46 PM

    You can follow this
    https://youtu.be/DIMjofO8Yt0

    and this
    http://www.sketchwarehelp.com/2018/03/check-for-latest-app-version-using.html?m=1

    to understand how to edit data in Sketchware.

    ReplyDelete
    Replies
    1. UnknownDecember 10, 2018 at 7:17 AM

      I tried your video about using firebase on name, english , science and such. It was doing great at first. But when I tried to save the data, it will not publish on the main xml, I cannot view the display custom. Please help me how to fix it.

      Delete
    2. UnknownDecember 10, 2018 at 7:19 AM

      I don't what is wrong.

      Delete
  10. MEDIA MAGICIANMay 14, 2018 at 11:04 PM

    sanjeev, i am working on app Water Quality Results. I want to show result when user enter an id. The result will retrieve/fetch from firebase database. Please help me.

    ReplyDelete
  11. UnknownJune 4, 2018 at 1:18 AM

    Greetings all.
    I'm developping an app but i'm facing a problem with user data.
    I'm using firebase and i wish to know how one user's datab is differentiated from another. Because i'm afraid when users will edit the data to database from the app, one user's info will delete another.
    I'm asking this because I want my app to have client space in such a way that each client has his personal infos! Help please

    ReplyDelete
  12. AnonymousJune 11, 2018 at 10:30 PM

    How to Retrieve customer details using customer id from firebase database.

    ReplyDelete
  13. UnknownJuly 14, 2018 at 2:52 PM

    Hi. My app view error when i click on the delete icon. Error message:
    Invalid list operation: Invalid index 14, size is 0.
    I dont have a sending images.

    ReplyDelete
  14. UnknownNovember 14, 2018 at 9:27 PM

    Hello how can i fix it. I get invalidlist operation
    :Invalid endex, 0 size is 0

    ReplyDelete
  15. Rahul VermaJanuary 20, 2019 at 11:42 AM

    Dear sir, if i create an app and login through firebase. And i wany to show users Name on the screen.
    How can I fetch users name from firebase of particular users??
    Please solve this .. i got stuck over here.

    ReplyDelete
  16. UnknownMarch 8, 2019 at 12:28 AM

    Storage uri cannot contains a path element ??

    ReplyDelete
  17. TIRTAGTNovember 4, 2019 at 7:02 PM

    This comment has been removed by the author.

    ReplyDelete
  18. Kundan kumarMay 26, 2020 at 12:02 AM

    Hlo sir how clear database in one click in sketchwere. Help me plz

    ReplyDelete
  19. hiddentrueeMay 26, 2020 at 6:13 AM

    This comment has been removed by the author.

    ReplyDelete
  20. hiddentrueeMay 26, 2020 at 6:14 AM

    I'm getting an error. but i wrote same code as yours.

    my app automatically land on a page(main page) if the user is loggedin. since I'm logged in in my app, i automatically land on that specific page(main page). that page has a button that will load profile edit page when it is clicked.



    but when my app load that edit profile page, it automatically go back to that main page(main page). i cant even edit profile. and then after some seconds, my app crashed! after that it show a bug report

    how can i fix this? is there any way i can send you my error reault? please help.

    ReplyDelete
    Replies
    1. sanjeevMay 26, 2020 at 8:50 AM

      Ther is some bug in onCreate or onChildAdded or onBindCustomView of your Profile edit page. Check the first few lines of the bug report.

      Delete
    2. hiddentrueeMay 26, 2020 at 11:02 AM

      java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Stringjava.lang.Object.toString()' on a null object reference at (project name).EditProfileActivity$ListView1Adapter.getView(EditProfileActltivity.java:401)




      note: i have discovered that, when i load that editprofile page(with "add new" button and listview item are set (according to your video)) then it shows the custom listview data in a list without crushing . but if i have 2/3 list of data, then i have to scroll down to see all the list data below, and when i finish scrolling that page, and at the last point of list it goes back to main page and then app crushes!

      Delete
    3. hiddentrueeMay 26, 2020 at 11:06 AM

      this project is very important for me. I'm making a blood grouping database for my medical college which is very important for our college to make it easy for people to find and contact donor quickly. if you help me with some other way( getting my code and fix this problem) it will be so helpful

      Delete
    4. sanjeevMay 26, 2020 at 5:58 PM

      It crashes because the length of the 2/3 lists you are using are different. The different lists should have same number of data. Or use a single maplist.

      Delete
    5. hiddentrueeMay 26, 2020 at 7:52 PM

      i sent you an email. can you read that please?

      Delete
    6. hiddentrueeMay 26, 2020 at 7:56 PM

      hello, I'm from bangladesh. i study in a medical college. I'm making a blood grouping and donor find app. I've recenlty tried your code from "simple database app" a youtube video.but its getting crushed. my app has a landing page(main page) if user is loggedin. when i open my app it load the main page as I'm loggedin. that main page has a button(profile). this button load profile page which has one button(edit) and a list view to view edited data in profile page.

      main page(if loggedin otherwise
      app's landing page is login page)>>profile page(a "edit" button and list view)>>edit page(has a save button, some edittext fields)


      after installation when i go to that profile page since i haven't added any data to that listview, app automatically goes back to main page. i dont kbow how! but it takes some time may be 2/3 sec. if i can somehow manage to click that edit button and can save the edit text fields( blank) twice( very quickly, even black save)then 2 list data are saved,although app crushes, but when second time i run app and go to that profile page, it shows a list of my data. since i saved all the edittext fields as blank, and i somehow managed to save that type of blank data twice, the list shows two list data, one in the screen, and to see another list, i have to scroll down. but if i scroll and finished scrolling that list( at that specific time, when i just finish scrolling) app automatically goes back to main page. and then crushes!


      i think there's something when i finish scrolling, the list item may be set null! and then i get an error message!


      error message:

      java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Stringjava.lang.Object.toString()' on a null object reference at (project name).EditProfileActivity$ListView1Adapter.getView(EditProfileActltivity.java:401)


      hope you will help me. if you want i can send you my project through sketchware share link. please help

      Delete
  21. hiddentrueeMay 31, 2020 at 11:46 PM

    This comment has been removed by the author.

    ReplyDelete
  22. hiddentrueeMay 31, 2020 at 11:48 PM

    i want to load some data from firebase from a particular location like this:

    location(all users)
    ...-uid
    ........-details
    .............-name
    .............-city
    ..............-phone



    how can i load all users details in a custom listview? please help

    ReplyDelete
  23. UnknownJune 16, 2020 at 2:55 AM

    dear sanjeev,
    one android developer told me,
    the apps we create using sketchware are counted as third party app(as we use third party app-sketchware). and every year google check if there's any third party app is play store. he also told me, all the third party apps create using sketchware or other 3rd party development tool will be deleted from play store by google.

    is this true? are the apps we create using sketchware counted as third party app? if so, will google remove apps created using sketchware?

    ReplyDelete
  24. UnknownNovember 10, 2020 at 1:12 AM

    Please I cant seem to find the "when view is clicked" block

    ReplyDelete
  25. UnknownDecember 12, 2020 at 2:04 AM

    Thank You
    It Helped Me

    ReplyDelete

Post a Comment

Popular posts from this blog

Simple car racing android game in Sketchware

Image
To create a simple car racing game in sketchware follow the steps given below. 1. Create a new project in Sketchware. 2. In VIEW area of main.xml add a TextView textview3 for displaying score of previous game, a TextView textview4 for displaying high score, and a Button button1 for starting game. 3. In MainActivity , add a Shared Preferences component sp:sp . 4. Add onStart event and put blocks to set the text of textview3 and textview4 . 5. Create a new page page2.xml . 6. On button1 click use intent to move to page2 . 7. On page2.xml add a LinearV linear1 with padding 0 and width and height MATCH_PARENT. 8. In Page2Activity , add a Shared Preferences component sp:sp . 9. Create a number variable highscore . 10. In onCreate event of Page2Activity , use blocks to set the value of number variable highscore , and use codes to create a new GameView and add it to linear1 , as shown in image below. The code used in the add source directly bloc
Read more

Enable Fullscreen for Youtube videos in WebView

Image
To enable fullscreen mode for YouTube videos in your sketchware project, follow the steps given below. 1. Create a new project in Sketchware. 2. In VIEW area add a WebView  webview1. 3. Create a more block  extra . 4. In the more block  extra , use an add source directly blocks and put codes to define a new WebChromeClient class with name CustomWebClient . } public class CustomWebClient extends WebChromeClient { private View mCustomView; private WebChromeClient.CustomViewCallback mCustomViewCallback; protected FrameLayout frame; // Initially mOriginalOrientation is set to Landscape private int mOriginalOrientation = android.content.pm.ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE; private int mOriginalSystemUiVisibility; // Constructor for CustomWebClient public CustomWebClient() {} public Bitmap getDefaultVideoPoster() { if (MainActivity.this == null) { return null; } return BitmapFactory.decodeResource(MainActivity.this.getApplicationContext().getResources
Read more

How to enable upload from webview in Sketchware?

Image
Now that Sketchware has a block to add java code directly in the project, it is possible to enable file upload in webview. To enable file upload in webview in sketchware app, follow the steps given below. 1. Insert a webview in VIEW area in the sketchware project. Note the ID of webview, usually it is webview1 . 2. In LOGIC area of project, in onCreate event, add the block add source directly and copy the following code in it: webview1.setWebChromeClient(new WebChromeClient() { // For 3.0+ Devices protected void openFileChooser(ValueCallback uploadMsg, String acceptType) { mUploadMessage = uploadMsg; Intent i = new Intent(Intent.ACTION_GET_CONTENT); i.addCategory(Intent.CATEGORY_OPENABLE); i.setType("image/*"); startActivityForResult(Intent.createChooser(i, "File Browser"), FILECHOOSER_RESULTCODE); } // For Lollipop 5.0+ Devices public boolean onShowFileChooser(WebView mWebView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChoose
Read more

Creating a Drawing View in Sketchware

Image
 To create a DrawingView with undo button, follow the instructions given below. 1. Create a new project in Sketchware. 2. In main.xml , add a LinearLayout linear1 with height wrap_content, weight 1, and padding 0. Add a LinearHorizontal below it, containing following ImageViews: imageview_stroke_width , imageview_stroke_color , imageview_background , imageview_undo,  and  imageview_clear. 3. Create a more block canvas and put following codes in it. Here we create a new View class called DrawingView and a new class called PathPaint. } DrawingView dv; private Paint mPaint; private Canvas mCanvas; private ArrayList<PathPaint> all_paths = new ArrayList<>(); public class DrawingView extends View { private Bitmap mBitmap; private Paint mBitmapPaint; Context context; private Paint circlePaint; private Path circlePath; private Path mPath; public DrawingView(Context c) { super(c); context=c; mPath = new Path(); mBitmapPaint = new Paint(Paint.DITHER_FLAG); circlePath = new Path();
Read more

List of Calendar Format symbols valid in Sketchware

Image
The calendar Format block in Sketchware provides a space where we can write the format in which we want the date or time to be displayed. We can use various symbols to construct our own custom date format. Here is a list of valid symbols along with their use which can be used in Sketchware for formatting the date/calendar. In all examples the date 12 Jul 2017 17:19:56 has been used. d : date of month without 0 prefix, e.g. 12. dd : date of month in two digits, e.g. 12. M : month in year, e.g. 7. MM : month in year in two digits, e.g. 07. MMM : month name in year displayed as three letter abbreviation, e.g. Jul. MMMM : month in year displayed as full month name, e.g. July. MMMMM : first letter of month name, e.g. J. y : year, e.g. 2017. yy : last two digits of year, e.g. 17. yyyy : year, e.g. 2017. h : hour in day in 12-hour format, e.g. 5. hh : hour in day in two digits, e.g. 05. H : hour in day in 24-hour format, e.g. 17. HH : hour in day 24-hour format in two
Read more