Parse.com get value with query

问题:

I've been looking for an example on how to use Parse.com queries. It's been really vague. I think it should start with:

ParseQuery query=ParseQuery.getQuery(<Class(aka table name)>);

But then, i've got no idea. You can do something like

query.whereEqualsTo(<collumn>,value)

In that case i get the 'value' back if it exists. What I am trying to do is. I got a table with the collumns ID and Name. I know what the ID is, it is 0. So now I want to know what Name belongs to the ID = 0.. But what query should I use, I have no idea ...

回答1:

Parse's Android Guide has a basic query example here which will return the first object which matches your constraints:

ParseQuery<ParseObject> query = ParseQuery.getQuery("YourClassName");
query.whereEqualTo("ID", "someID");
query.getFirstInBackground(new GetCallback<ParseObject>() {
  public void done(ParseObject object, ParseException e) {
    if (object == null) {
      Log.d("score", "The getFirst request failed.");
    } else {
      Log.d("score", "Retrieved the object.");
    }
  }
});

回答2:

I would not recommend using getFirstInBackground for getting a query, it is much better to use findInBackGround and then filtering the value you are looking for.

回答3:

To find the list of user whose username starts with abc,You can use the condition

query.whereStartsWith("username", "abc");

So the entire query looks as

ParseQuery<ParseObject> query = ParseQuery.getQuery("YourClassName");
query.whereStartsWith("username", "abc");
query.findInBackground(new FindCallback<ParseObject>() {
  public void done(List<ParseObject> object, ParseException e) {
    if (object == null) {
      Log.d("score", "The getFirst request failed.");
    } else {
      Log.d("score", "Retrieved the object.");
    }
  }
});