fix(Arguments) use the type's coerce method, raise an error if the co…

…ercion fails

lib/graphql/base_type.rb

@@ -65,5 +65,19 @@ def to_s
     end
 
     alias :inspect :to_s
+
+    # Coerce `input_value` according to this type's `coerce` method.
+    # Raise an error if the value becomes nil.
+    # @param [Object] Incoming query value
+    # @return [Object] Coerced value for query execution
+    def coerce!(input_value)
+      coerced_value = coerce(input_value)
+
+      if coerced_value.nil?
+        raise GraphQL::ExecutionError.new("Couldn't coerce #{input_value.inspect} to #{self.unwrap.name}")
+      end
+
+      coerced_value
+    end
   end
 end

lib/graphql/query/arguments.rb

@@ -11,8 +11,11 @@ def initialize(ast_arguments, argument_hash, variables)
     end
   end
 
-  def_delegators :@hash, :keys, :values, :inspect, :to_h
+  def_delegators :@hash, :keys, :values, :inspect, :to_h, :key?, :has_key?
 
+  # Find an argument by name.
+  # (Coerce to strings because we use strings internally.)
+  # @param [String, Symbol] Argument name to access
   def [](key)
     @hash[key.to_s]
   end
@@ -21,9 +24,10 @@ def [](key)
 
   def reduce_value(value, arg_defn, variables)
     if value.is_a?(GraphQL::Language::Nodes::VariableIdentifier)
-      value = variables[value.name]
+      raw_value = variables[value.name]
+      value = arg_defn.type.coerce!(raw_value)
     elsif value.is_a?(GraphQL::Language::Nodes::Enum)
-      value = arg_defn.type.coerce(value.name)
+      value = arg_defn.type.coerce!(value.name)
     elsif value.is_a?(GraphQL::Language::Nodes::InputObject)
       wrapped_type = arg_defn.type.unwrap
       value = self.class.new(value.pairs, wrapped_type.input_fields, variables)

spec/graphql/query_spec.rb

@@ -30,10 +30,11 @@
   |}
   let(:debug) { false }
   let(:operation_name) { nil }
+  let(:query_variables) { {"cheeseId" => 2} }
   let(:query) { GraphQL::Query.new(
     DummySchema,
     query_string,
-    variables: {"cheeseId" => 2},
+    variables: query_variables,
     debug: debug,
     operation_name: operation_name,
   )}
@@ -194,4 +195,28 @@
       end
     end
   end
+
+  describe "query variables" do
+    let(:query_string) {%|
+      query getCheese($cheeseId: Int!){
+        cheese(id: $cheeseId) { flavor }
+      }
+    |}
+
+    describe "when they can be coerced" do
+      let(:query_variables) { {"cheeseId" => 2.0} }
+
+      it "coerces them on the way in" do
+        assert("Gouda", result["data"]["cheese"]["flavor"])
+      end
+    end
+
+    describe "when they can't be coerced" do
+      let(:query_variables) { {"cheeseId" => "2"} }
+
+      it "raises an error" do
+        assert(result["errors"][0]["message"].include?(%{Couldn't coerce "2" to Int}))
+      end
+    end
+  end
 end