fix(request): build request body by operation payload field (Kong#126)

This is a follow-up fix for Kong#120 .

The PR modifies the request build again with the following changes: when the payload field is specified inside the input schema, the request body will be built based on the parameter that specified by the payload field.

This behavior imitates the behavior defined in aws-sdk-js: https://github.com/aws/aws-sdk-js/blob/02153340ce052614c5437fe46ab1f49bfd8483f7/lib/protocol/rest_json.js#L24-L41
as well as https://github.com/aws/aws-sdk-js/blob/02153340ce052614c5437fe46ab1f49bfd8483f7/lib/protocol/rest_xml.js#L10-L26

FTI-6138

Author: windmgc

README.md

@@ -177,6 +177,12 @@ Release process:
 1. test installing the rock from LuaRocks
 
 
+### Unreleased
+
+- fix: build the request body based on payload field
+  [126](https://github.com/Kong/lua-resty-aws/pull/126)
+
+
 ### 1.5.2 (29-Jul-2024)
 
 - fix: fix sts regional endpoint injection under several cases

spec/02-requests/02-build_request_spec.lua

@@ -5,9 +5,9 @@ describe("operations protocol", function()
 
 
   local build_request
-  local operation
-  local config
-  local params
+  local operation, operation_with_payload_field
+  local config, config_with_payload
+  local params, params_with_payload
   local snapshot
   local binary_data
 
@@ -105,6 +105,37 @@ describe("operations protocol", function()
       }
     }
 
+    operation_with_payload_field = {
+      name = "PutObject",
+      http = {
+        method = "PUT",
+        requestUri = "/{Bucket}/{Key+}"
+      },
+      input = {
+        type = "structure",
+        required = {
+          "Bucket",
+          "Key"
+        },
+        members = {
+          Bucket = {
+            type = "string",
+            location = "uri",
+            locationName = "Bucket"
+          },
+          Key = {
+            type = "string",
+            location = "uri",
+            locationName = "Key"
+          },
+          Body = {
+            type = "blob",
+          },
+        },
+        payload = "Body"
+      },
+    }
+
     config = {
       apiVersion = "2011-06-15",
       --endpointPrefix = "sts",
@@ -119,6 +150,19 @@ describe("operations protocol", function()
       xmlNamespace = "https://sts.amazonaws.com/doc/2011-06-15/"
     }
 
+    config_with_payload = {
+      apiVersion = "2006-03-01",
+      signingName = "s3",
+      globalEndpoint = "s3.amazonaws.com",
+      --protocol = "query",
+      serviceAbbreviation = "AWS S3",
+      serviceFullName = "AWS Object Storage",
+      serviceId = "S3",
+      signatureVersion = "v4",
+      uid = "s3-2006-03-01",
+      xmlNamespace = "https://s3.amazonaws.com/doc/2006-03-01/"
+    }
+
     params = {
       RoleArn = "hello",
       RoleSessionName = "world",
@@ -134,6 +178,12 @@ describe("operations protocol", function()
       BinaryData = binary_data,
     }
 
+    params_with_payload = {
+      Bucket = "hello",
+      Key = "world",
+      Body = binary_data,
+    }
+
   end)
 
 
@@ -256,6 +306,27 @@ describe("operations protocol", function()
     }, request)
   end)
 
+  it("json: querystring, uri, header and body params, with payload field", function()
+
+    config_with_payload.protocol = "json"
+
+    local request = build_request(operation_with_payload_field, config_with_payload, params_with_payload)
+
+    assert.same({
+      headers = {
+        ["Content-Length"] = 4,
+        ["X-Amz-Target"] = "s3.PutObject",
+        ["Host"] = "s3.amazonaws.com",
+      },
+      method = 'PUT',
+      path = '/hello/world',
+      host = 's3.amazonaws.com',
+      port = 443,
+      body = binary_data,
+      query = {},
+    }, request)
+  end)
+
 
   it("rest-xml: querystring, uri, header and body params", function()
 

src/resty/aws/request/build.lua

@@ -205,6 +205,21 @@ local function build_request(operation, config, params)
     request.query[k] = v
   end
 
+  local payload_member = operation.input and operation.input.payload
+  if payload_member and body_tbl[payload_member] then
+    local member_config = operation.input.members[payload_member]
+    if member_config.type == "structure" then
+      body_tbl = type(body_tbl[payload_member]) == "table" and body_tbl[payload_member] or body_tbl
+
+    elseif body_tbl[payload_member] then
+      request.body = body_tbl[payload_member]
+      if member_config.type == "binary" and member_config.streaming == true then
+        request.headers["Content-Type"] = "binary/octet-stream"
+      end
+      body_tbl[payload_member] = nil
+    end
+  end
+
   local table_empty = not next(body_tbl)
   -- already has a raw body, or no body at all
   if request.body then