Correctly serialize/deserialize header lists (#2611)

Author: alextwoods

build_tools/aws-sdk-code-generator/spec/protocols/input/rest-json.json

@@ -110,6 +110,65 @@
       }
     ]
   },
+  {
+    "description": "Header list of strings",
+    "metadata": {
+      "protocol": "rest-json",
+      "apiVersion": "2014-01-01"
+    },
+    "shapes": {
+      "InputShape": {
+        "type": "structure",
+        "members": {
+          "ListOfStrings": {
+            "shape": "StringList",
+            "location": "header",
+            "locationName": "x-amz-string-list"
+          },
+          "String": {
+            "shape": "String",
+            "location": "header",
+            "locationName": "x-amz-string"
+          }
+        }
+      },
+      "StringList": {
+        "type": "list",
+        "member": {
+          "shape": "String"
+        }
+      },
+      "String": {
+        "type": "string"
+      }
+    },
+    "cases": [
+      {
+        "given": {
+          "http": {
+            "method": "GET",
+            "requestUri": "/path"
+          },
+          "input": {
+            "shape": "InputShape"
+          },
+          "name": "OperationName"
+        },
+        "params": {
+          "ListOfStrings": ["value1", "value2"],
+          "String": "singleValue"
+        },
+        "serialized": {
+          "body": "",
+          "uri": "/path",
+          "headers": {
+            "x-amz-string": "singleValue",
+            "x-amz-string-list": "value1,value2"
+          }
+        }
+      }
+    ]
+  },
   {
     "description": "Querystring list of strings",
     "metadata": {

build_tools/aws-sdk-code-generator/spec/protocols/output/rest-json.json

@@ -854,6 +854,11 @@
           },
           "ListEnums": {
             "shape": "EnumList"
+          },
+          "HeaderListEnums": {
+            "shape": "EnumList",
+            "location": "header",
+            "locationName": "x-amz-enum-list"
           }
         }
       },
@@ -886,11 +891,12 @@
         "result": {
           "HeaderEnum": "baz",
           "FooEnum": "foo",
-          "ListEnums": ["foo", "bar"]
+          "ListEnums": ["foo", "bar"],
+          "HeaderListEnums": ["foo", "bar"]
         },
         "response": {
           "status_code": 200,
-          "headers": {"x-amz-enum": "baz"},
+          "headers": {"x-amz-enum": "baz", "x-amz-enum-list":  "foo,bar"},
           "body": "{\"FooEnum\": \"foo\", \"ListEnums\": [\"foo\", \"bar\"]}"
         }
       },

build_tools/aws-sdk-code-generator/spec/protocols_spec.rb

@@ -191,7 +191,7 @@ def normalize_xml(xml)
     describe 'input' do
       each_test_case(self, files['input']) do |group, suite, test_case, name|
 
-        group.it "marshalls response data correctly" do
+        group.it "marshals response data correctly" do
           client = client_for(suite, test_case, "Input_#{name}")
           ctx = nil
           client.handle(step: :send) do |context|

gems/aws-sdk-core/CHANGELOG.md

@@ -1,6 +1,8 @@
 Unreleased Changes
 ------------------
 
+* Issue - Correctly serialize/deserialize header lists.
+
 3.122.0 (2021-11-04)
 ------------------
 

gems/aws-sdk-core/lib/aws-sdk-core/rest/request/headers.rb

@@ -35,6 +35,7 @@ def apply_header_value(headers, ref, value)
           headers[ref.location_name] =
             case ref.shape
             when TimestampShape then timestamp(ref, value)
+            when ListShape then list(ref, value)
             else value.to_s
             end
         end
@@ -49,6 +50,10 @@ def timestamp(ref, value)
           end
         end
 
+        def list(_ref, value)
+          value.compact.join(",")
+        end
+
         def apply_header_map(headers, ref, values)
           prefix = ref.location_name || ''
           values.each_pair do |name, value|
@@ -57,7 +62,7 @@ def apply_header_map(headers, ref, values)
         end
 
         # With complex headers value in json syntax,
-        # base64 encodes value to aviod weird characters
+        # base64 encodes value to avoid weird characters
         # causing potential issues in headers
         def apply_json_trait(value)
           Base64.strict_encode64(value)

gems/aws-sdk-core/lib/aws-sdk-core/rest/response/headers.rb

@@ -40,6 +40,8 @@ def cast_value(ref, value)
           when IntegerShape then value.to_i
           when FloatShape then value.to_f
           when BooleanShape then value == 'true'
+          when ListShape then
+            value.split(",").map { |v| cast_value(ref.shape.member, v) }
           when TimestampShape
             if value =~ /^\d+(\.\d*)/
               Time.at(value.to_f)