jonkeane commented on a change in pull request #10326:
URL: https://github.com/apache/arrow/pull/10326#discussion_r634492852
##########
File path: r/R/dataset.R
##########
@@ -93,8 +93,19 @@ open_dataset <- function(sources,
return(dataset___UnionDataset__create(sources, schema))
}
factory <- DatasetFactory$create(sources, partitioning = partitioning, ...)
- # Default is _not_ to inspect/unify schemas
- factory$Finish(schema, isTRUE(unify_schemas))
+
+ tryCatch(
+ # Default is _not_ to inspect/unify schemas
+ factory$Finish(schema, isTRUE(unify_schemas)),
+ error = function (e) {
+ msg <- conditionMessage(e)
+ if(grep("Parquet magic bytes not found in footer", msg)){
+ stop("Looks like these are not parquet files, did you mean to specify
a 'format'?", call. = FALSE)
+ } else {
+ stop(e)
Review comment:
Ah, I was thinking about the line 105 stop. I'm not certain if passing
`e` there will have the same behavior as it would now (for errors that aren't
this parquet issue, like providing a non-existent directory). Currently (on the
master branch) that looks like:
```
> ds <- open_dataset("~/does/not/exist")
Error: IOError: Cannot list directory '/Users/jkeane/does/not/exist'.
Detail: [errno 2] No such file or directory
```
But with this change it might be something like the following without also
adding `call. = FALSE` here too (though I'm not certain of that!)
```
Error in open_dataset() : Error: IOError: Cannot list directory
'/Users/jkeane/does/not/exist'. Detail: [errno 2] No such file or directory
```
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