Demonstrate poor handling of cyclic datastructures #111
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This PR is not meant to ever be merged. This is a demonstration of some broken behavior around handling datastructures with cyclic dependencies. The problem is if we provide a struct to `MarshalQueryWithOptions()` and that struct has cyclic fields, even if not populated, and even if we provide a Field that limits the output to a set depth, `MarshalQueryWithOptions()` will still recurse infinitely and cause a panic due to exhausting the stack. This is a big problem because goql is a GraphQL library, and GraphQL is for querying graph datastructures, and datastructures in graphs will very commonly have cyclic relationships because graphs have cycles :) The correct behavior would be to: 1. If no Fields are provided, do not recursively walk into fields of structs that've already been walked. This is safe to do because GraphQL already doesn't allow infinite expansion; if you want relationships, even recursive ones, to a particular depth then GQL will force you to specify that in your query. Thus we can assume that you'll have to specify that to `goql` via a `Fields` param. 2. If `Fields` *are* provided, we can recursively walk already walked fields, but only to the depth specified in those `Fields`. Future work will have to be done to get this behavior to work.
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What this PR does / why we need it
This PR is not meant to ever be merged. This is a demonstration of some broken behavior around handling datastructures with cyclic dependencies. The problem is if we provide a struct to
MarshalQueryWithOptions()and that struct has cyclic fields, even if not populated, and even if we provide a Field that limits the output to a set depth,MarshalQueryWithOptions()will still recurse infinitely and cause a panic due to exhausting the stack.This is a big problem because goql is a GraphQL library, and GraphQL is for querying graph datastructures, and datastructures in graphs will very commonly have cyclic relationships because graphs have cycles :)
The correct behavior would be to:
goqlvia aFieldsparam.Fieldsare provided, we can recursively walk already walked fields, but only to the depth specified in thoseFields.Future work will have to be done to get this behavior to work.
Jira ID
No jira for this (yet)
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