[GitHub] [arrow] thisisnic commented on a diff in pull request #34798: GH-15247: [R] Error when trying to save a data.frame with NULL column names

["thisisnic (via GitHub)" <gi...@apache.org>]

thisisnic commented on code in PR #34798:
URL: https://github.com/apache/arrow/pull/34798#discussion_r1154168985


##########
r/R/csv.R:
##########
@@ -782,12 +782,16 @@ write_csv_arrow <- function(x,
     tryCatch(
       x <- as_record_batch_reader(x),
       error = function(e) {
-        abort(
-          paste0(
-            "x must be an object of class 'data.frame', 'RecordBatch', ",
-            "'Dataset', 'Table', or 'RecordBatchReader' not '", class(x)[1], "'."
+        if (grepl("Input data frame columns must be named", conditionMessage(e))) {
+          abort(conditionMessage(e), parent = NA)

Review Comment:
   I'm not sure `parent = e` does exactly what you think; here's the error with `parent = NA`:
   ```
   Error in write_csv_arrow(x, tempfile()) : 
     Input data frame columns must be named
   ℹ Column names are NULL
   ```
   
   and here's the error with `parent = e`:
   
   ```
   Error in write_csv_arrow(x, tempfile()) : 
     Input data frame columns must be named
   ℹ Column names are NULL
   Caused by error:
   ! Input data frame columns must be named
   ℹ Column names are NULL
   ```
   
   I think `parent = NA` is a better fit in all cases.  Current error in the other condition with no parent specified:
   
   ```
   Error in value[[3L]](cond) : 
     x must be an object of class 'data.frame', 'RecordBatch', 'Dataset', 'Table', or 'RecordBatchReader' not 'function'.
   ```
   
   With `parent = NA`:
   ```
   Error in write_csv_arrow(c, tempfile()) : 
     x must be an object of class 'data.frame', 'RecordBatch', 'Dataset', 'Table', or 'RecordBatchReader' not 'function'.
   ```
   
   With `parent = e`:
   ```
   Error in write_csv_arrow(c, tempfile()) : 
     x must be an object of class 'data.frame', 'RecordBatch', 'Dataset', 'Table', or 'RecordBatchReader' not 'function'.
   Caused by error in `inherits()`:
   ! argument "schema" is missing, with no default
   ```
   
   I've updated it both so they have `parent = NA`.



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