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

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

     [ https://issues.apache.org/jira/browse/ARROW-18200?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Nicola Crane reassigned ARROW-18200:
------------------------------------

    Assignee: Nicola Crane

> [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
>            Assignee: Nicola Crane
>            Priority: Major
>
> 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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