parse cloud code sample code

gistfile1.js

Parse.Cloud.beforeSave("Posts", function(request, response) {
    if (request.object.existed()) {
        return response.success(); // the Post already exist, this must be an Update action
    } 
    // do a query to "Posts" to check the oldest related "Posts" to current user
    var query = new Parse.Query("Posts");
    query.equalTo("PostUser", Parse.User.current());
    query.equalTo("Topic", YOUR_REFERENCED_TOPIC_OBJECT); // assume you are want to reference it by pointer
    query.descending("createdAt");
    query.first({
        success: function(object) {
            if (object) {
                // check for the time period limitation
                response.error("Timeout.");
            } else {
                response.success();
            }
        },
        error: function(error) {
            response.error("Could not save request. Error: " + error);
        }
    });
});

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