Flex Template Align Error

[FawenYo]

System Informations

• Go version: 1.23.2-alpine3.20
• OS: alpine
• Package version: github.com/line/line-bot-sdk-go/v8 v8.10.0

Expected Behavior

Here is a simple Flex message I design with the Flex Message Simulator tool

{
  "type": "bubble",
  "body": {
    "type": "box",
    "layout": "vertical",
    "contents": [
      {
        "type": "box",
        "layout": "horizontal",
        "contents": [
          {
            "type": "text",
            "text": "測試",
            "size": "sm",
            "color": "#555555",
            "flex": 0
          },
          {
            "type": "text",
            "text": "123",
            "size": "sm",
            "color": "#111111",
            "align": "end"
          }
        ]
      }
    ]
  },
  "styles": {
    "footer": {
      "separator": true
    }
  }
}

and the message should look like this

Current Behavior

Here is part of my Golang code

jsonString := fmt.Sprintf(`{
"type": "bubble",
"body": {
	"type": "box",
	"layout": "vertical",
	"contents": [
	{
		"type": "box",
		"layout": "horizontal",
		"contents": [
		{
			"type": "text",
			"text": "測試",
			"size": "sm",
			"color": "#555555",
			"flex": 0
		},
		{
			"type": "text",
			"text": "123",
			"size": "sm",
			"color": "#111111",
			"align": "end"
		}
		]
	}
	]
},
"styles": {
	"footer": {
	"separator": true
	}
}
}`)
		  
contents, err := messaging_api.UnmarshalFlexContainer([]byte(jsonString))
if err != nil {
	log.WithField("userName", displayName).WithField("userID", userID).Errorf("Failed to unmarshal flex container: %s", err)
	replyMessage = &messaging_api.TextMessage{
		Text: "Failed to unmarshal",
	}
}

replyMessage = &messaging_api.FlexMessage{
	AltText:  "Test",
	Contents: contents,
}
if _, err := bot.ReplyMessage(
	&messaging_api.ReplyMessageRequest{
		ReplyToken: replyToken,
		Messages:   []messaging_api.MessageInterface{replyMessage},
	},
); err != nil {
	log.WithField("userName", displayName).WithField("userID", userID).Errorf("Failed to reply message: %s", err)
}

and the sent image looks like this

The align format is quite different from the expected one.

Steps to Reproduce

1. Follow the example flex message JSON above to test to send with the SDK

Logs

No obvious error log

[FawenYo]

So I just found where the problem is...

For content without the flex key, the SDK automatically adds flex: 0 to the component attribute. However, flex:0 could break the design.
I don't know if the behavior in the SDK is a bug or if it was added out of kindness, but I suggest not adding this key.

(FYI, until the fixed build comes out, you can add flex: 999 to those components without flex as a temporary solution.

[habara-k]

Thank you for using the messaging API and the line-bot-sdk-go.
We apologize for the delayed response.

The behavior you're experiencing is due to the fact that FlexText.Flex is of the int32 type, which defaults to 0. Using a pointer type for int32 would allow us to distinguish between null and 0, but this would result in a breaking change to the SDK's specifications.

For the time being, as you suggested, please specify a value like flex:999 to work around the issue.
We apologize for any inconvenience this may cause.
Thank you for your patience.