one-to-many scalability and efficiency of getting the many - parse.com
I have a question about the scalability of getting the many from a one-to-many relationship in parse.com. Below is a diagram of what I am trying to do.
I have a Like object that has a userWhoLiked and a messageLiked attributes as pointers. My question is in regards to checking if a User has liked a message already when loading a feed of Message objects. I was thinking that I could write some cloud code that would return both the Message itself as well as information about if the User has already liked that object. However, I feel like this would be very inefficient. I would in essence have a query for all the Message objects (which will be n objects long), and then another query for finding if the User has already liked that Message object by going through all the Like objects n times and checking the userWhoLiked and messageLiked based on the user logged in and Message I am checking. I am going to use the pointer to build the one-to-many relationship because the number of Like objects will be arbitrarily large. Is the method that I have described (using cloud code and then checking the Like objects ) for getting if a user has liked an object is okay and scalable? Is there a better way, or any suggestions? I appreciate your time. Thanks.
Why not just do one query on Like objects where the userWhoLiked key is equal to the current user? This will return all of the objects which the current user has liked and you can also infer that all objects not included have not been liked.
In case you haven't checked it out yet, I'd highly recommend the Parse Anypic tutorial which has a very similar structure
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