I've built an application that uses Parse. My application allows users to register, login and then post to a parse cloud database.
I have two Parse classes, one called User and one called Posts. User is made up of ObjectId, username and password, and Posts is made up of ObjectId, text and user. Of which user is a pointer to ObjectId within the User class.
I've created a method in my app called getData() which contains a ParseQuery, this queries the Posts class, selects the text field and includes the user field. The query then retrieves the data into a List and then loops through each row of the List, collecting the String from the text field and then adds it into a ListView on the UI using postList.add(textList.get(i).getString("text")); each time the program goes through the loop.
Within the loop is another query, which queries the User class, selects the objectId field, I then add a constraint to the query to tell it to only retrieve data where the objectId field is equal to the user field within the Posts class(I think).
ParseQuery<ParseObject> queryUser = ParseQuery.getQuery("User");
queryUser.selectKeys(Arrays.asList("objectId"));
queryUser.whereEqualTo("objectId", textList.get(i).getString("user"));
Next I want to take the collected username data that the query retrieved, put it into a String and display it on screen in a toast. So basically the getData() method should collect all of the strings from the text field and the username of the user that posted it.
The problem is that I'm unsure if i'm trying to go about this in the right way. My app throws an error when this piece of code is executed so I'm obviously doing something wrong.
java.lang.IllegalStateException: ParseObject has no data for this key. Call fetchIfNeeded() to get the data.
at com.parse.ParseObject.checkGetAccess(ParseObject.java:3235)
at com.parse.ParseObject.getString(ParseObject.java:2817)
at com.text.parse.MainActivity$3.done(MainActivity.java:186)
Code at line 186 : queryUser.whereEqualTo("objectId", textList.get(i).getString("user"));
My questions are:
1. Am I trying to do this in the right way?
2. Why am I receiving this error?
Code for getData() method:
public void getData() {
final ArrayList<String> postList = new ArrayList<String>();
final ArrayAdapter<String> listAdapter = new ArrayAdapter<String>(this, R.layout.listview_row, postList);
final ParseQuery<ParseObject> queryPosts = ParseQuery.getQuery("Posts");
queryPosts.selectKeys(Arrays.asList("text"));
queryPosts.include("user");
queryPosts.addDescendingOrder("createdAt");
queryPosts.setLimit(20);
queryPosts.findInBackground(new FindCallback<ParseObject>() {
@Override
public void done(List<ParseObject> textList, ParseException e) {
if (e == null) {
//query successful
for (int i = 0; i < textList.size(); i++) {
postList.add(textList.get(i).getString("text"));
ParseQuery<ParseObject> queryUser = ParseQuery.getQuery("User");
queryUser.selectKeys(Arrays.asList("objectId"));
queryUser.whereEqualTo("objectId", textList.get(i).getString("user"));
queryUser.setLimit(20);
queryUser.findInBackground(new FindCallback<ParseObject>() {
@Override
public void done(List<ParseObject> userList, ParseException e) {
if (e == null) {
String s = userList.get(0).getString("username").toString();
Toast.makeText(MainActivity.this, s, Toast.LENGTH_LONG).show();
}
else {
//query error
Toast.makeText(MainActivity.this, "query error: " + e, Toast.LENGTH_LONG).show();
}
}
});
}
lvText.setAdapter(listAdapter);
} else {
//query error
Toast.makeText(MainActivity.this, "query error: " + e, Toast.LENGTH_LONG).show();
}
}
});
}
Sorry for the long question. Any help would be greatly appreciated, thanks.
UPDATE:
For anyone stuck with a similar problem, here's how I got it to work:
public void getData() {
final ArrayList<String> postList = new ArrayList<String>();
final ArrayAdapter<String> listAdapter = new ArrayAdapter<String>(this, R.layout.listview_row, postList);
final ParseQuery<ParseObject> queryPosts = ParseQuery.getQuery("Posts");
queryPosts.include("user");
queryPosts.addDescendingOrder("createdAt");
queryPosts.setLimit(20);
queryPosts.findInBackground(new FindCallback<ParseObject>() {
@Override
public void done(List<ParseObject> textList, ParseException e) {
if (e == null) {
//query successful
for (int i = 0; i < textList.size(); i++) {
postList.add(textList.get(i).getString("text"));
ParseObject po1 = textList.get(i);
ParseObject po2 = po1.getParseObject("user");
String username = po2.getString("username");
Toast.makeText(MainActivity.this, username, Toast.LENGTH_SHORT).show();
}
lvText.setAdapter(listAdapter);
} else {
//query error
Toast.makeText(MainActivity.this, "query error: " + e, Toast.LENGTH_LONG).show();
}
}
});
}
You simply include the column in the class you are querying that holds a pointer to another class, that then gives you access to all of the columns of data within the second class.
