From 98646ed98d5a85053da709c4a46442d01df14bbd Mon Sep 17 00:00:00 2001
From: Joe Gaudet <joe.gaudet@food.ee>
Date: Fri, 21 Apr 2017 11:35:52 -0700
Subject: [PATCH] Fix an issue with redis keys not hitting

When writing to a redis store, the keys used by JR are converted to
slash delimited strings. So:

key = [record_type, id, updated at]

Gets converted to record_type/id/updated_at

This causes the lookup function to never get hits from the redis store.

This commit adds a configurable function to allow formating of the
lookup key.
---
 lib/jsonapi/cached_resource_fragment.rb |  5 +++++
 lib/jsonapi/configuration.rb            | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/lib/jsonapi/cached_resource_fragment.rb b/lib/jsonapi/cached_resource_fragment.rb
index 4a6d598d4..eb76535ef 100644
--- a/lib/jsonapi/cached_resource_fragment.rb
+++ b/lib/jsonapi/cached_resource_fragment.rb
@@ -81,6 +81,11 @@ def self.lookup(resource_klass, serializer_config_key, context, context_key, cac
       hits = JSONAPI.configuration.resource_cache.read_multi(*keys).reject{|_,v| v.nil? }
       return keys.each_with_object({}) do |key, hash|
         (_, id, _, _) = key
+
+        if JSONAPI.configuration.resource_cache_key_format_function
+          key = JSONAPI.configuration.resource_cache_key_format_function(key)
+        end
+
         if hits.has_key?(key)
           hash[id] = self.from_cache_value(resource_klass, context, hits[key])
         else
diff --git a/lib/jsonapi/configuration.rb b/lib/jsonapi/configuration.rb
index 52c34ab81..fe2fbef21 100644
--- a/lib/jsonapi/configuration.rb
+++ b/lib/jsonapi/configuration.rb
@@ -35,6 +35,7 @@ class Configuration
                 :resource_cache,
                 :default_resource_cache_field,
                 :resource_cache_digest_function,
+                :resource_cache_key_format_function,
                 :resource_cache_usage_report_function
 
     def initialize
@@ -140,6 +141,12 @@ def initialize
       # Optionally provide a callable which JSONAPI will call with information about cache
       # performance. Should accept three arguments: resource name, hits count, misses count.
       self.resource_cache_usage_report_function = nil
+
+      # Resource cache key formating
+      # Optionally provide a callable which JSONAPI will call in order to format your cache
+      # key, this is useful for stores such as redis, which cannot be queried using an array
+      # the way the rails in memory cache can
+      self.resource_cache_usage_report_function = nil
     end
 
     def cache_formatters=(bool)
@@ -256,7 +263,10 @@ def default_record_accessor_klass=(default_record_accessor_klass)
 
     attr_writer :resource_cache_digest_function
 
+    attr_writer :resource_cache_key_format_function
+
     attr_writer :resource_cache_usage_report_function
+
   end
 
   class << self