Apache Commons CSV doesn't ignore missing column

Question

Using Apache Commons CSV for parsing, but doesn't ignore missing column and throws exception.

with this sample data:

name age
Ali 35
John 25
Vahid 75

Below code record.get(DataColumns.surname) throws java.lang.IllegalArgumentException: Mapping for surname not found, expected one of [name, surname, age]. I need it returns null, optional or default value. Is there any option? I know it is possible with record.toMap().get(DataColumns.surname.name()) but its performance will not be good:

...
enum DataColumns { name, surname, age }
...
Reader in = new BufferedReader(new FileReader(fileName));

try (CSVParser records = CSVFormat.TDF
                .withDelimiter(' ')
                .withIgnoreSurroundingSpaces()
                .withAllowDuplicateHeaderNames(false)
                .withIgnoreHeaderCase()
                .withTrim()
                .withHeader(DataColumns.class)
                .withFirstRecordAsHeader()
                .withSkipHeaderRecord()
                .withAllowMissingColumnNames(false)
                .withIgnoreEmptyLines()
                .parse(in)) {

   for (CSVRecord record : records) {
       String name = record.get(DataColumns.name);
       String surname = record.get(DataColumns.surname);
       Short age = Short.valueOf(record.get(DataColumns.age)); 
   }
}

...

Haroldo_OK · Accepted Answer · 2019-11-27 14:03:22Z

1

You might try using record.isMapped(columnName) to check if the column exists, recording into a variable so you don't have to check again every line.

Another option would be to use records.getHeaderNames() and store it into a variable once, before the loop, maybe even using a Set<String> for an extra kick of existance checking performance: Set<String> headerNames = new HashSet<>(records.getHeaderNames()).

Then, you can use the resulting variable inside the loop by calling headerNames.contains(columnName) to check whether the column exists or not.

Plese, see: https://javadoc.io/doc/org.apache.commons/commons-csv/latest/org/apache/commons/csv/CSVRecord.html

edited Nov 27, 2019 at 14:03

answered Nov 27, 2019 at 13:31

Haroldo_OK

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4 Comments

nikli Over a year ago

This is ok, but for more columns maybe it will decrease performance

Haroldo_OK Over a year ago

One workaround would be to store its return value into a variable on the first record

nikli Over a year ago

Check only one time?

Haroldo_OK Over a year ago

Exactly; you may get missing cells between one row or the other, but the column names will stay the same

dzwiedziuu · Accepted Answer · 2019-11-27 13:31:56Z

0

There is method: record.get(String) while you gave enum instead.

Try record.get(DataColumns.name.name())

answered Nov 27, 2019 at 13:31

dzwiedziuu

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2 Comments

Avi Over a year ago

Please try to explain your answer.

nikli Over a year ago

They are same thing, overload method String get(Enum<?> e) calls String get(String name)

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