This function along with others changes would solve #274

Author: topepo

R/repair_call.R

@@ -0,0 +1,57 @@
+#' Repair a model call object
+#'
+#' When the user passes a formula to `fit()` _and_ the underyling model function
+#' uses a formula, the call object produced by `fit()` may not be usable by
+#' other functions. For example, some arguments may still be quosures and the
+#' `data` portion of the call will not correspond to the original data.
+#'
+#' `repair_call()` call can adjust the model objects call to be usable by other
+#' functions and methods.
+#' @param x A fitted `parsnip` model. An error will occur if the underlying model
+#'  does not have a `call` element.
+#' @param data A data object that is relavant to the call. In most cases, this
+#'  is the data frame that was given to `parsnip` for the model fit (i.e., the
+#'  training set data). The name of this data object is inserted into the call.
+#' @return A modified `parsnip` fitted model.
+#' @examples
+#'
+#' fitted_model <-
+#'   linear_reg() %>%
+#'   set_engine("lm", model = TRUE) %>%
+#'   fit(mpg ~ ., data = mtcars)
+#'
+#' # In this call, note that `data` is not `mtcars` and the `model = ~TRUE`
+#' # indicates that the `model` argument is an `rlang` quosure.
+#' fitted_model$fit$call
+#'
+#' # All better:
+#' repair_call(fitted_model, mtcars)$fit$call
+#' @export
+repair_call <- function(x, data) {
+  cl <- match.call()
+  if (!any(names(x$fit) == "call")) {
+    rlang::abort("No `call` object to modify.")
+  }
+  if (rlang::is_missing(data)) {
+    rlang::abort("Please supply a data object to `data`.")
+  }
+  fit_call <- x$fit$call
+  needs_eval <- purrr::map_lgl(fit_call, rlang::is_quosure)
+  if (any(needs_eval)) {
+    eval_args <- names(needs_eval)[needs_eval]
+    for(arg in eval_args) {
+      fit_call[[arg]] <- rlang::eval_tidy(fit_call[[arg]])
+    }
+  }
+  if (any(names(fit_call) == "data")) {
+    fit_call$data <- cl$data
+  }
+
+  x$fit$call <- fit_call
+  x
+}
+
+mod2_fit$fit$call
+repair_call(mod2_fit, mtcars)$fit$call
+
+