Using parse.com with android, I am retrieving a parseObject in a method and I want to update the same exact object in another method without having to retrieve it again. What is the best way to do this?
Here is my attempt:
I tried to save a copy of the object when first retrieved and change this copy and then save this copy using saveInBackground method. I highly doubt that this would work. The copy will be saved but the original object won't be saved, so what is the alternative?
method that retrieves the object:
query.getFirstInBackground(new GetCallback<ParseObject>() {
public void done(ParseObject object, ParseException e) {
MyShop = object;
}
method that updates the object:
public void OnClick(View arg0){
MyShop.put("status", false);
MyShop.saveInBackground();
}
Where MyShop is a global variable and I want to update the ParseObject object
It turned out that copies of the same ParseObject refer to the same object on cloud, meaning if one copy is updated the original copy is updated. It looks like all of them are references to the same object, maybe because this is Java
Related
I am applying filters on realm using RealmResults<>.
I begin to do like this -
RealmResults<data> filteredRealmResults;
List<data> tranfilteredlist;
private OrderedRealmCollectionChangeListener<RealmResults<data>> filteredTransChangeListener =
new OrderedRealmCollectionChangeListener<RealmResults<data>>() {
#Override
public void onChange(RealmResults<data> results, OrderedCollectionChangeSet changeSet) {
Log.d("realm", "filteredRealmResults.size():" + filteredRealmResults.size());
tranfilteredlist = results;
initFilterAdapter();
}
};
Now I want to delete the filteredRealmResults. I did like this -
void deleteFilteredRealmResults() {
realm.executeTransaction(new Realm.Transaction() {
#Override
public void execute(Realm realm) {
// Delete all matches
filteredRealmResults.deleteAllFromRealm();
}
});
}
After doing this my data in the realm got deleted. So I just try to delete the tranfilteredlist but it throws an exception that it does not support .clear();
I want to clear if from the memory whatever is holder the query data. Correct me if I am wrong or doesn't understand or just worrying too much.
I read This class holds all the matches of a RealmQuery for a given Realm. The objects are not copied from the Realm to the RealmResults list, but are just referenced from the RealmResult instead. This saves memory and increases speed.
I want to clear if from the memory whatever is holder the query data.
Correct me if I am wrong or doesn't understand or just worrying too
much.
Once you invoke filteredRealmResults.deleteAllFromRealm, it will clear the internal resultant elements object(which holds the elements) and as you know, resultant objects are reference so data will be deleted from realm database too. Hence, there is no need to call clear on the RealmResults object.
You can verify this by calling filteredRealmResults.size() after deletion, it will return 0.
I just try to delete the tranfilteredlist but it throws an exception
that it does not support .clear();
It is the expected behaviour as clear has been deprecated so don't use it.
Why deprecated?
deleteAllFromRealm automatically clears the list so no need to call it again explicitly.
Calling clear on RealmResults object will result in deletion of data from database, can cause unexpected behaviour if the user is not aware so API is being modified to avoid unexpected behaviours.
I don't understand how is the Parse working?
I download data in parse to my arraylist , but when I show the Pets.size inside (//here) method "done" it will show 4, but when I show pets.size outside the done's method it will show 0?
public class Test extends AppCompatActivity {
ArrayList<Pet> pets;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
pets = new ArrayList<>();
ParseQuery<Pet> query = new ParseQuery<>("Pets");
query.findInBackground(new FindCallback<Pet>() {
#Override
public void done(List<Pet> list, ParseException e) {
if (e!=null){
Toast.makeText(Test.this,"Error",Toast.LENGTH_LONG).show();
}
for (Pet pet : list){
Pet newPet = new Pet();
newPet.setName(pet.getName());
newPet.setType(pet.getType());
pets.add(newPet);
}
// here
}
});
Toast.makeText(Test.this,"You have "+pets.size()+" pets",Toast.LENGTH_LONG).show();
}
Here's my Pet class:
#ParseClassName("Pets")
public class Pet extends ParseObject {
public String getName(){
return getString("name");
}
public void setName(String name) {
put("name", name);
}
public String getType(){
return getString("type");
}
public void setType(String type) {
put("type", type);
}
}
And an orther question , what should I do if I wanna save the data in local data?
Explanation:
findInbackground performs an operation to find all ParseObjects in a background thread (outside the main thread, or UI thread). So when it completes in the place where you have the comment
//here
That is when the background thread finishes it's call to find the objects. When you try to look at the size of the array outside that call where it shows size of 0, it is because it reached that point before the background thread finishes it's work (of adding to your array from objects it found).
What is happening is the operation for find() is happening in parallel with your main threads code.
And for your second question, make sure you enableLocalDatastore and then you can pin results from queries to your local cache. This data is stored on the device until the user deletes your app or clears cached data in settings.
Follow this guide to setup local cache Local Datastore with Parse
Note: A solution to your problem for when the background task of finding the pets is complete is to call a method from within the Callback for the findInBackground call that will handle the newly found Pet ParseObjects. Also remember to handle if the query fails either by finding no objects or some failure in connection / timeout.
just calling pet.pin() or pet.pinInBackground(); you can save a parseObject in local storage , to query objects in local storage you need set query.fromPin(true)
https://parse.com/docs/android/guide#objects-the-local-datastore
"done" method fires when the background task ends.
I'm unable to properly fetch a ParseObject that contains a field of type 'Object' : after changing manually the 'Object' field value in the Parse DataBrowser and then fetch the ParseObject from the app, the fetched ParseObject still provide the old value for the 'Object' field, but provide the right new value for the 'String' field.
Here is the sample code I use :
public class MainActivity extends ActionBarActivity {
ParseObject object;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
object = ParseObject.createWithoutData("Test", "tvgTg8jAXz");
}
#Override
protected void onResume() {
super.onResume();
object.fetchInBackground().onSuccess(new Continuation<ParseObject, Object>() {
#Override
public Object then(Task<ParseObject> task) throws Exception {
JSONObject data = task.getResult().getJSONObject("data");
String name = task.getResult().getString("name");
Log.d("OBJECT", data.toString());
Log.d("OBJECT", name);
return null;
}
}).continueWith(new Continuation<Object, Object>() {
#Override
public Object then(Task<Object> task) throws Exception {
if (task.getError() != null) {
Log.e("OBJECT", task.getError().getLocalizedMessage());
}
return null;
}
});
}
}
After I change both 'data' and 'name' fields in the DataBrowser, if 'onResume()' is called without a previous call to 'onCreate()' (after locking/unlocking screen for example) then the logs shows the old value for 'data' and the new value for 'name'.
This is a simple code example to highlight the problem I encounter in a bigger project.
Is this a known issue of the Parse Android SDK ? Is there a workaround ?
Thanks
Now that I learned that you have turned on the local datastore I can come with an, at least partial, answer.
Turning on the local datastore has some side effects. One being that only one instance of each object exists locally. So when you call fetchInBackground the second time, object is already populated with data. The problem then (i think) is that the API no longer override 'complex' types (pointers, objects, arrays), perhaps because it could mess up internal relationships in the data store. Since the fact that the data store will recursively save an object (and pointers) so suddenly swapping a pointer might leave objects 'hanging'. (again, only guessing).
Now I must admit that it still confuses me a bit looking at your code, cause it does not seem that you at any point write your object to the data store, however..
What should work is to unpin the object before 'refreshing' it:
object.unpinInBackground.onSuccess(new Continuation<>{
...
// when done call fetch
});
According to Parse, this is a known issue that they will not fix for now : https://developers.facebook.com/bugs/1624269784474093/
We must use the following methods to retrieve JSON objects/arrays fields from a ParseObject :
getMap() instead of getJSONObject()
getList() instead of getJSONArray()
These methods will return Map and List objects respectively.
I found that managing Map and List in my project instead of JSONObjet and JSONArray is not a problem and is even clearer.
Hi I am trying to update the location of the current device into the parse database using the objectId of this device.
ParseQuery innerQuery = new ParseQuery("_Installation");
innerQuery.whereEqualTo("objectId", ParseInstallation.getCurrentInstallation());//current phone
ParseQuery<PhoneFinder> query = ParseQuery.getQuery(PhoneFinder.class);
query.whereMatchesQuery("identification", innerQuery);
query.findInBackground(new FindCallback<PhoneFinder>() {
#Override
public void done(List<PhoneFinder> list, ParseException e) {
for (PhoneFinder loc : list)
{
loc.setLocation(geoPoint);
loc.saveInBackground();
}
}
});
If I use the objectId explicitly is works fine.
Any suggestions?
You haven't said what's wrong with the code you posted (that is, exactly what it does wrong) but I'm going to guess innerQuery doesn't return any rows. If that is the case, this information from the API docs may help:
Note: We only allow the following types of queries for installations:
query.get(objectId)
query.whereEqualTo("installationId", value)
query.whereMatchesKeyInQuery("installationId", keyInQuery, query)
whereEqualTo("objectId",value) isn't on that list, so that is probably why it's not working. Also, ParseInstallation.getQuery is the best way to get a query to use for installations.
i made a listview with all the posts in the list.
what i want is when i click the child in the list i want another activity to be opened showing that specific post and the related comments
the question is how to know which item is clicked and how to show that particular post ParseObject in next activity
as they do in messaging app in which you click the message from the listview and subsequent messages are shown in the next activity
i might be very thankful to you if you solve this for me!!
Please Try this code:
Please implement your object class with Serializable
listView.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapter, View v, int position,
long arg3) {
try
{
Log.v("position",position); // hear is your list item position
MyClass obj = new MyClass(); // Class must be implements with Serializable
Intent showintent = new Intent(context,<activity class to open>);
showcontactintent.putExtra("obj",obj);
startActivity(showintent);
}
catch(Exception e)
{
e.printStackTrace();
}
}
});
Use: Relational Data
Objects can have relationships with other objects. To model this behavior, any ParseObject can be used as a value in other ParseObjects. Internally, the Parse framework will store the referred-to object in just one place, to maintain consistency.
For example, each Comment in a blogging app might correspond to one Post. To create a new Post with a single Comment, you could write:
// Create the post
ParseObject myPost = new ParseObject("Post");
myPost.put("title", "I'm Hungry");
myPost.put("content", "Where should we go for lunch?");
// Create the comment
ParseObject myComment = new ParseObject("Comment");
myComment.put("content", "Let's do Sushirrito.");
// Add a relation between the Post and Comment
myComment.put("parent", myPost);
// This will save both myPost and myComment
myComment.saveInBackground();
You can also link objects using just their objectIds like so:
// Add a relation between the Post with objectId "1zEcyElZ80" and the comment
myComment.put("parent", ParseObject.createWithoutData("Post", "1zEcyElZ80"));
By default, when fetching an object, related ParseObjects are not fetched. These objects' values cannot be retrieved until they have been fetched like so:
fetchedComment.getParseObject("post")
.fetchIfNeededInBackground(new GetCallback<ParseObject>() {
public void done(ParseObject post, ParseException e) {
String title = post.getString("title");
// Do something with your new title variable
}
});
You can also model a many-to-many relation using the ParseRelation object. This works similar to List, except that you don't need to download all the ParseObjects in a relation at once. This allows ParseRelation to scale to many more objects than the List approach. For example, a User may have many Posts that they might like. In this case, you can store the set of Posts that a User likes using getRelation. In order to add a post to the list, the code would look something like:
ParseUser user = ParseUser.getCurrentUser();
ParseRelation<ParseObject> relation = user.getRelation("likes");
relation.add(post);
user.saveInBackground();
You can remove a post from the ParseRelation with something like:
relation.remove(post);
For more read: https://parse.com/docs/android/guide#objects-relational-data
^why did I copy all the words here instead of just providing the link? Because parse links are broken sometimes and doesn't direct you to the section you need (instead it just sends you to https://parse.com/docs/android/guide and because the doc is so large, you won't be able to find it.