allow priming loaders

Author: repomaa

spec/graphql-dataloader/loader_spec.cr

@@ -100,4 +100,42 @@ describe GraphQL::DataLoader::Loader do
     loader.batch_log.size.should eq(1)
     loader.batch_log.first.should eq([1, 2])
   end
+
+  it "primes the cache" do
+    users = [
+      User.new(1, "Ada"),
+      User.new(2, "Grace"),
+    ]
+    loader = UserLoader.new(users)
+    loader.prime(1, users[0])
+    loader.load(1).should eq(users[0])
+    loader.load(2).should eq(users[0])
+    loader.batch_log.size.should eq(1)
+  end
+
+  it "clears the cache" do
+    users = [
+      User.new(1, "Ada"),
+      User.new(2, "Grace"),
+    ]
+    loader = UserLoader.new(users)
+    loader.load(1).should eq(users[0])
+    loader.clear
+    loader.load(1).should eq(users[0])
+    loader.batch_log.size.should eq(2)
+  end
+
+  it "clears a single cache entry" do
+    users = [
+      User.new(1, "Ada"),
+      User.new(2, "Grace"),
+    ]
+    loader = UserLoader.new(users)
+    loader.load(1).should eq(users[0])
+    loader.prime(2, users[1])
+    loader.clear(1)
+    loader.load(1).should eq(users[0])
+    loader.load(2).should eq(users[1])
+    loader.batch_log.size.should eq(2)
+  end
 end

src/graphql-dataloader/cache.cr

@@ -11,9 +11,12 @@ module GraphQL::DataLoader
       end
     end
 
-    private abstract def has_key?(key : K) : Bool
-    private abstract def [](key : K) : V
-    private abstract def []=(key : K, value : V) : Nil
+    abstract def has_key?(key : K) : Bool
+    abstract def [](key : K) : V
+    abstract def []?(key : K) : V?
+    abstract def []=(key : K, value : V) : Nil
+    abstract def delete(key : K) : Nil
+    abstract def clear : Nil
 
     # Override this method for caches where values expire for thread safety
     private def synchronize(&block : -> V) : V

src/graphql-dataloader/loader.cr

@@ -39,6 +39,21 @@ module GraphQL::DataLoader
       objects.map { |object| load(object) }
     end
 
+    def prime(object : O, value : V) : self
+      cache[key_for(object)] ||= value
+      self
+    end
+
+    def clear(object : O) : self
+      cache.delete(key_for(object))
+      self
+    end
+
+    def clear : self
+      cache.clear
+      self
+    end
+
     # The batch loading method.
     # Gets called with all objects that have been passed to `#load` in the current batch.
     # A batch is fetched after 1 microsecond since the first call to `#load`.

src/graphql-dataloader/memory_cache.cr

@@ -4,16 +4,28 @@ module GraphQL::DataLoader
 
     private getter cache = Hash(K, V).new
 
-    private def has_key?(key : K) : Bool
+    def has_key?(key : K) : Bool
       cache.has_key?(key)
     end
 
-    private def [](key : K) : V
+    def [](key : K) : V
       cache[key]
     end
 
-    private def []=(key : K, value : V) : Nil
+    def []?(key : K) : V?
+      cache[key]?
+    end
+
+    def []=(key : K, value : V) : Nil
       cache[key] = value
     end
+
+    def clear : Nil
+      cache.clear
+    end
+
+    def delete(key : K) : Nil
+      cache.delete(key)
+    end
   end
 end