问题
Somehow I couldn't find the answer to this.
I am running a query to parse.com and want to download all of the rows that contain an empty value in one of my columns.
ParseQuery<ParseObject> query = ParseQuery.getQuery(Constants.myTestTable);
query.whereEqualTo("MyColumn", "");
When I upload a csv to parse where MyColumn does not have any value the column cells on parse show "(undefined)" and I cannot retrieve the data. However, when I delete all content in the cell I am able to retrieve it. I want to be able to retrieve the data if the cell has the default "(undefined)" value from parse. I tried...
ParseQuery<ParseObject> query = ParseQuery.getQuery(Constants.myTestTable);
query.whereEqualTo("MyColumn", null);
But that did not work either. I'm sure there is an easy solution to this, I just can't get the dang thing to work.
回答1:
What you want are whereExists and whereDoesNotExist.
query.whereDoesNotExist("MyColumn");
来源：https://stackoverflow.com/questions/24463734/queries-with-empty-values-from-parse-com