body is null in LoggerWithFormatter

i have a problems when i try loggin del body because de body is null

gin.LoggerWithFormatter(func(param gin.LogFormatterParams) string {
	
		body, err := ioutil.ReadAll(param.Request.Body)

the problem is in my controller i have this code

	var body entities.WriteChatRequest
	if err := c.ShouldBindJSON(&body); err != nil {
		c.JSON(400, gin.H{"error": err.Error()})
		return
	}

the body was converted but now is null, when the controller finished and i try logging

Start by locating the example that configures gin.LoggerWithFormatter and the controller using ShouldBindJSON. Reproduce the request, then inspect how the request body is handled by the binding and logging paths. Done means the example can log the submitted body after the controller has processed it without a null body.