java - 查询 ParseObject

Question

我正在尝试使用 Parse 查询获取对象。

这是我的代码:

ParseQuery<ParseObject> query = ParseQuery.getQuery("Conference");
    query.findInBackground(new FindCallback<ParseObject>() {
        public void done(List<ParseObject> results, ParseException e) {
            if (e == null) {
                // Results were successfully found from the local datastore.
            } else {
                showLog(e.toString());
            }
        }
    });

我收到这个错误:

com.parse.ParseException: java.lang.IllegalStateException: ParseObject has no data for 'objectId'. Call fetchIfNeeded() to get the data.

顺便说一句，我的 Conference 类包含指针。

Answer 1

如果您直接从 Parse 查询，您可以:

ParseQuery<ParseObject> query = ParseQuery.getQuery("Conference");
...
query.include("name_of_the_column_containing_a_pointer");
query.include("another_pointer_column");
query.findInBackground(new FindCallback<ParseObject>() {
    public void done(List<ParseObject> results, ParseException e) {
        if (e == null) {
            // You can now access the pointers specified in the include
        } else {
            showLog(e.toString());
        }
    }
});

否则，如果您正在查询本地数据存储:

ParseQuery<ParseObject> query = ParseQuery.getQuery("Conference");
...
query.findInBackground(new FindCallback<ParseObject>() {
    public void done(List<ParseObject> results, ParseException e) {
        if (e == null) {
            ParseObject parseObject = results.get(0); // Get the object
            parseObject.fetchIfNeededInBackground(new GetCallback<ParseObject>() {
                public void done(ParseObject result, ParseException e) {
                    if (e == null)
                        // Do something with result
                }
            }
        } else {
            showLog(e.toString());
        }
    }
});