Description:
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Hello. I think it would be very useful to have otput filtering built in PDO. For example if use fetchAll() I get raw data which might have XSS javascript inside. Then I have to filter it somehow e.g. htmlspecialchars. 
I think it would be great if such filtering could be done with method like fetchAllFiltered(array('number','string','html');
For example if i have a table posts and it looks like id, title, body then when calling fetchAllFiltered('number','string','html') i would get id sanitized as a number, title sanitized as a string or simply with htmlspecialchars() and a body which would get sanitized as html. e.g. no javascript inside, but all html tags present.
 Currently to filter the data coming from database usually is used filter_var or htmlspecialchars or anything else which i think is one more step in development which could be dropped using fetchAllFiltered().
 Also i think that filtering could be added in default fetch methods of PDO as an array argument which describes filtering of output for those methods. 
For example: fetchAll(array('number',string','html')); and we get the filtered output.