[jira] [Created] (ARROW-18200) [R] Misleading error message if opening CSV dataset with invalid file in directory

["Nicola Crane (Jira)" <ji...@apache.org>]

Nicola Crane created ARROW-18200:
------------------------------------

             Summary: [R] Misleading error message if opening CSV dataset with invalid file in directory
                 Key: ARROW-18200
                 URL: https://issues.apache.org/jira/browse/ARROW-18200
             Project: Apache Arrow
          Issue Type: Bug
          Components: R
            Reporter: Nicola Crane


I made a mistake before where I thought a dataset contained CSVs which were, in fact, Parquet files, but the error message I got was super unhelpful

{code:r}
library(arrow)

download.file(
  url = "https://github.com/djnavarro/arrow-user2022/releases/download/v0.1/nyc-taxi-tiny.zip",
  destfile = here::here("data/nyc-taxi-tiny.zip")
)
 # (unzip the zip file into the data directory but don't delete it after)

open_dataset("data", format = "csv")
{code}


{code:r}
Error in nchar(x) : invalid multibyte string, element 1
In addition: Warning message:
In grepl("No match for FieldRef.Name(__filename)", msg, fixed = TRUE) :
  input string 1 is invalid in this locale
{code}

Note, this only occurs with {{format="csv"}} and omitting this argument (i.e. the default of {{format="parquet"}} leaves us with the much better error:


{code:r}
Error in `open_dataset()`:
! Invalid: Error creating dataset. Could not read schema from '/home/nic2/arrow_10_twitter/data/nyc-taxi-tiny.zip': Could not open Parquet input source '/home/nic2/arrow_10_twitter/data/nyc-taxi-tiny.zip': Parquet magic bytes not found in footer. Either the file is corrupted or this is not a parquet file.
/home/nic2/arrow/cpp/src/arrow/dataset/file_parquet.cc:338  GetReader(source, scan_options). Is this a 'parquet' file?
/home/nic2/arrow/cpp/src/arrow/dataset/discovery.cc:44  InspectSchemas(std::move(options))
/home/nic2/arrow/cpp/src/arrow/dataset/discovery.cc:265  Inspect(options.inspect_options)
ℹ Did you mean to specify a 'format' other than the default (parquet)?
{code}





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