Golang - Gin BindJSON to []byte

Question: I'm using GORM and the Gin Web Framework to create a RESTful API. I'm trying to bind the body of a JSON request with BindJSON to the model, but the model contains a slice of byte leading to an error. How can I bind the body to the model without changing the datatype to string?

Model:

type User struct {
    Password []byte `json:"password" binding:"required"`
}

Request Body:

{
    "password": "mypassword"
}

Controller:

r.PUT("/user", func(c *gin.Context) {
    var user User
    err := c.BindJSON(&user)
    if err != nil {
        fmt.Println(err)
        return
    }
})

Error: illegal base64 data at input byte 12

This error appears, as Gin tries to bind a string (from the JSON body) to a []byte (from the model) and fails.

Solution that I don't like: I know that the solution could be to create a different struct with the Password as type string like following and add it to the controller, so that BindJSON works properly:

type user struct {
    Password string `json:"password" binding:"required"`
}

This solution does not reflect my model and I need to add extra code. How can I adapt my model/context binding?