[R] Construct booster object in load.raw. (#7686)

R-package/R/xgb.load.raw.R

@@ -3,12 +3,21 @@
 #' User can generate raw memory buffer by calling xgb.save.raw
 #'
 #' @param buffer the buffer returned by xgb.save.raw
+#' @param as_booster Return the loaded model as xgb.Booster instead of xgb.Booster.handle.
 #'
 #' @export
-xgb.load.raw <- function(buffer) {
+xgb.load.raw <- function(buffer, as_booster = FALSE) {
   cachelist <- list()
   handle <- .Call(XGBoosterCreate_R, cachelist)
   .Call(XGBoosterLoadModelFromRaw_R, handle, buffer)
   class(handle) <- "xgb.Booster.handle"
-  return (handle)
+
+  if (as_booster) {
+    booster <- list(handle = handle, raw = NULL)
+    class(booster) <- "xgb.Booster"
+    booster <- xgb.Booster.complete(booster, saveraw = TRUE)
+    return(booster)
+  } else {
+    return (handle)
+  }
 }

R-package/man/xgb.load.raw.Rd

@@ -4,10 +4,12 @@
 \alias{xgb.load.raw}
 \title{Load serialised xgboost model from R's raw vector}
 \usage{
-xgb.load.raw(buffer)
+xgb.load.raw(buffer, as_booster = FALSE)
 }
 \arguments{
 \item{buffer}{the buffer returned by xgb.save.raw}
+
+\item{as_booster}{Return the loaded model as xgb.Booster instead of xgb.Booster.handle.}
 }
 \description{
 User can generate raw memory buffer by calling xgb.save.raw

R-package/tests/testthat/test_io.R

@@ -19,17 +19,8 @@ test_that("load/save raw works", {
   ubj_bytes <- xgb.save.raw(booster, raw_format = "ubj")
   old_bytes <- xgb.save.raw(booster, raw_format = "deprecated")
 
-  from_json <- xgb.load.raw(json_bytes)
+  from_json <- xgb.load.raw(json_bytes, as_booster = TRUE)
-  from_ubj <- xgb.load.raw(ubj_bytes)
+  from_ubj <- xgb.load.raw(ubj_bytes, as_booster = TRUE)
-
-  ## FIXME(jiamingy): Should we include these 3 lines into `xgb.load.raw`?
-  from_json <- list(handle = from_json, raw = NULL)
-  class(from_json) <- "xgb.Booster"
-  from_json <- xgb.Booster.complete(from_json, saveraw = TRUE)
-
-  from_ubj <- list(handle = from_ubj, raw = NULL)
-  class(from_ubj) <- "xgb.Booster"
-  from_ubj <- xgb.Booster.complete(from_ubj, saveraw = TRUE)
 
   json2old <- xgb.save.raw(from_json, raw_format = "deprecated")
   ubj2old <- xgb.save.raw(from_ubj, raw_format = "deprecated")