$util.map.copyAndRemoveAllKeys is not working

[yukitaka13-1110]

I'm developing appsync with serverless-framewrok.
I use dynamodb so I implemented vtl resolver files.
But copyAndRemoveAllKeys is not working.

See the following example code.
This is a respose.vtl code.

#if($ctx.error)
    $util.error($ctx.error.message, $ctx.error.type)
#end
#set($messages = $ctx.result.items)
#set($mergedMessages = [])
#set($users = $ctx.prev.result.items)
#foreach($m in $messages)
  #set($uid = $m.uid)
  #foreach($user in $users)
    #if($uid == $user.id)
      #set($m = $util.map.copyAndRemoveAllKeys($m, ["uid"])) ## This line.
      $util.qr($m.put("user", $user))
      $util.qr($mergedMessages.add($m))
      #break
    #end
  #end
#end
#set($result = { "items": $mergedMessages })
$util.toJson($result)

This always returns null and no error occurred.
I deployed this code and query it.
Unfortunately, I could retrieve expected response, not null.

query

query MyQuery {
  listChatMessages(groupId: "group-001") {
    items {
      id
      postDate
      user {
        color
        groupId
        id
      }
    }
  }
}

AppSync console result

{
  "data": {
    "listChatMessages": {
      "items": [
        {
          "id": "group-001",
          "postDate": "2021-06-23T01:00:01Z",
          "user": {
            "color": "blue",
            "groupId": "group-001",
            "id": "user-001"
          }
        },
        {
          "id": "group-001",
          "postDate": "2021-06-23T01:02:01Z",
          "user": {
            "color": "red",
            "groupId": "group-001",
            "id": "user-002"
          }
        }
      ]
    }
  }
}

Local AppSync Simulator

{
  "data": {
    "listChatMessages": null
  }
}

Is this bug?

Environment

"dependencies": {
    "serverless-appsync-plugin": "^1.11.3",
    "serverless-appsync-simulator": "^0.17.0",
    "serverless-dynamodb-local": "^0.2.39",
    "serverless-offline": "^7.0.0",
    "webpack": "^5.40.0",
    "webpack-cli": "^4.7.2",
    "webpack-node-externals": "^3.0.0"
  }

[bboure]

@yukitaka13-1110 This is a known issue in amplify-cli

I have noticed it too and haven't had time to fix it.
a PR/issue should be opened in amplify-cli.

It happens because ["uid"] is not transformed into a JavaArray

In the meantime, here is the workaround I use:

#set($remove=["uid"])
#set($m = $util.map.copyAndRemoveAllKeys($m, $remove)) ## This works

[yukitaka13-1110]

@bboure Thank you for your response!
I'll try it.

Additionally, I found $HashMap.size() is not working with the following error.

Error: Missing request mapping template.

Do you have any idea about this?

[yukitaka13-1110]

@bboure I confirmed my code worked correctly in AppSync console query.

[yukitaka13-1110]

@bboure Sample code.

#set($obj = {})
#set($count = -1)

#set($count = $obj.size())

Local simulator: Missing request mapping template errror
AppSync Console: no error

[bboure]

Thanks @yukitaka13-1110
Is that the full template? If so, it resolves to an empty template. I am not sure un what case that would happen? (maybe in pipelines??)

I know by experience that empty templates don't work, but I thought it was an AppSync, not simulator.
Templates should usually be JSON parsable. If the template does not return anything, I usually return {}

I will have a try at this. In any case, that would also be an issue in amplify-cli that we could fix there.

[yukitaka13-1110]

@bboure I found node version v16.0.0 caused this error.
Change to v12.0.0 then error disappeared but size() !== actual.

See this.

#set($records = [
  { "id": "id-001"},
  { "id": "id-002"},
  { "id": "id-001"},
  { "id": "id-002"},
])

#set($obj = {})
#foreach($record in $records)
    #if($util.isNull($obj[$record.id]))
        $util.qr($obj.put($record.id, 1))
    #else
        #set($count = $obj[$record.id] + 1)
        $util.qr($obj.put($record.id, $count))
    #end
#end

## $obj = \":{\"id-001\":1,\"id-002\":1}
## $obj.size() -> 4 but expected 2

I think this occurs when put same key twice.

#set($records = [
  { "id": "id-001"},
  { "id": "id-002"},
])

#set($obj = {})
#foreach($record in $records)
    #if($util.isNull($obj[$record.id]))
        $util.qr($obj.put($record.id, 1))
    #else
        #set($count = $obj[$record.id] + 1)
        $util.qr($obj.put($record.id, $count))
    #end
#end

## $obj = \":{\"id-001\":1,\"id-002\":1}
## $obj.size() -> 2 expected 2

[yukitaka13-1110]

@bboure In AppSync console, I got expected result.

#set($records = [
  { "id": "id-001"},
  { "id": "id-002"},
  { "id": "id-001"},
  { "id": "id-002"}
])

#set($obj = {})
#foreach($record in $records)
    #if($util.isNull($obj[$record.id]))
        $util.qr($obj.put($record.id, 1))
    #else
        #set($count = $obj[$record.id] + 1)
        $util.qr($obj.put($record.id, $count))
    #end
#end
#set($count = $obj.size())
#set($result = { "obj": $obj, "count": $count })
$util.error($util.toJson($result), "debug")

"{\"obj\":{\"id-001\":2,\"id-002\":2},\"count\":2}

[stale]

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