For this, you can use c.ShouldBindBodyWith.

  objA := formA{}
  objB := formB{}
  // This reads c.Request.Body and stores the result into the context.
  if errA := c.ShouldBindBodyWith(&objA, binding.JSON); errA == nil {
    c.String(http.StatusOK, `the body should be formA`)
    c.String(http.StatusOK, `the body should be formB JSON`)
  // And it can accepts other formats
  } else if errB2 := c.ShouldBindBodyWith(&objB, binding.XML); errB2 == nil {
    c.String(http.StatusOK, `the body should be formB XML`)
    ...
  }
}

• stores body into the context before binding. This has
  a slight impact to performance, so you should not use this method if you are
  enough to call binding at once.
• This feature is only needed for some formats — JSON, XML, MsgPack,
  ProtoBuf. For other formats, Query, Form, FormPost, FormMultipart,
  can be called by multiple times without any damage to
  performance (See ).