How to query value of column that is set as pointe

问题:

I am using Parse for my app. I want to query a table with column that set to be a pointer to other table. Here is the query:

ParseQuery query = new ParseQuery("CategoryAttribute");
        query.whereEqualTo("categoryId", categoryId);
        query.findInBackground(new FindCallback() {
            @Override
            public void done(List<ParseObject> categoryAttributes, ParseException e) {
                if (e == null) {
                    for (int i = 0; i < categoryAttributes.size(); i++){
                        String atributeCategoryId = categoryAttributes.get(i).getString("categoryId");
                        String attributeKey  = categoryAttributes.get(i).getString("attributeKey");
                        String attributeValue   = categoryAttributes.get(i).getString("attributeValue");

                        setCategoryAtributeRow(atributeCategoryId, attributeKey, attributeValue);
                    }
                } else {
                    Log.d("score", "Error: " + e.getMessage());
                }
            }
        });

So the categoryId column is a pointer to other table. Other columns work fine. I tried to scan the API and the guides but couldn't find needed solution. Help would be much appreciated!

回答1:

Here is the solution to this one:

First you need to create a ParseObject from the type of your table:

ParseObject sale = ParseObject.createParseObject("Sale"); 

Then you need to get the ParseObject from the result:

sale = result.getParseObject(pointer_field);

Now you can pull from sale any field that it has just as you would do it normally, for example:

sale.getString("some_field")

Note: When you are doing your query you must to include the pointer field if you want to be able to extract the data from it after the query will be returned. The result:

query.include("pointer_field")

Hope it helps

回答2:

@Akshat Agarwal, here is a example in JavaScript:

var parseObj = Parse.Object.extend('parseObj');

new Parse.Query(parseObj)
  .include('pointerField')
  .find(function (data) {
    data.get('pointerField').get('fieldName');
  });

回答3:

For iOS

  PFQuery *parseQuery = [PFQuery queryWithClassName:@"MyClass"];
  [parseQuery whereKey:@"categoryId" equalTo:categoryId];
  [parseQuery includeKey:@"pinter_field"];
  [parseQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
  //
  }];