javascript - See the updated document in allow / deny rule in Meteor.js -

i'd specify allow rule document update in meteor.js depend on properties of updated document. in update callback, old document, list of changed top-level fields , mongo modifier. there easy way determine how document if updated?

 

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a non-trivial real-life example: i've got party model maxcount integer specifies how many people can fit in party, , people array names of people attending. user can push several names array. i'd allow update made if in resulting document length of array not exceed maxcount.

this perfect example of why allow/deny rules in current form insufficient real world problems. there multitude of ways document can updated, , it's impractical check of them tools allow/deny gives you. i'd should use them if permissions like: "the owner of document can whatever wants document".

that being said, if really want example above try checking if people.length < maxcount when modifier['$push']['people'] defined.

as far know, general solution problem not exist. why use methods db mutations.

you can have @ simple-schema , collection2 (i haven't tried them). according docs, simple-schema can take function when defining min/max on field. i'm unclear if means can dynamically define min/max based on object being updated or not.