fetchAssoc() fails with freshly created Reader

[shadowhand]

Issue summary

I need to pre-process a CSV file that was given to me that contains a number of columns with duplicate names. In order to process this file I am creating a reader, writing some columns with a writer, and then getting a reader:

$reader = Reader::createFromPath('path/to/file.csv');
$write = Writer::createFromStream(fopen('php://temp', 'r+'));
$columns_to_extract = [1, 2, 3, 4, 5, 43];

foreach ($reader->fetch() as $row) {
    $write->insertOne(array_intersect_key($row, $columns_to_extract));
}

$reader = $write->newReader()->setOffset(0);

And then I pass the $reader into another class that uses fetchAssoc():

function process(Reader $csv)
{
    foreach ($csv->fetchAssoc() as $row) {
        // do stuff with row
    }
}

This works fine for other CSVs, but as soon as I add this pre-processing step, I get the following error:

InvalidArgumentException: the specified row does not exist or is empty in importer/vendor/league/csv/src/Reader.php on line 338

Call Stack:
    0.0002     233496   1. {main}() importer/bin/import:0
    0.0255    1522728   2. League\Csv\Reader->fetchAssoc() importer/bin/import:17
    0.0255    1522928   3. League\Csv\Reader->getAssocKeys() importer/vendor/league/csv/src/Reader.php:247
    0.0255    1523208   4. League\Csv\Reader->getRow() importer/vendor/league/csv/src/Reader.php:281

System informations

(In case of a bug report Please complete the table below)

Information	Description
League\Csv version	8.2.0
PHP/HHVM version	5.6.29
OS Platform	osx

Standalone code, or other way to reproduce the problem

See description.

Expected result

No error.

Actual result

Exception thrown.

[shadowhand]

For whatever reason, the following code works:

foreach ($reader->fetch() as $row) {
    $write->insertOne(array_intersect_key($row, $columns_to_extract));
}

$reader = Reader::createFromString((string) $write);

[nyamsprod]

@shadowhand it works because the latter uses SplTempFileObject while the first example uses a userland StreamIterator to enable Writer::createFromStream. I'll review your fix and merge it since I have to release a patch version with other fixes hopefully later this week or next week.

[shadowhand]

My "fix" appears to break other things. :) I'll trust you can sort it out.

[nyamsprod]

@shadowhand while waiting for the patch in your code if you change

$write = Writer::createFromStream(fopen('php://temp', 'r+'));
//by
$write = Writer::createFromFileObject(new SplTempFileObject());

It will work.

[nyamsprod]

@shadowhand the PR #215 should fix your code could you try it please if it's ok for you I'll release the patch

[nyamsprod]

version 8.2.1 is out with the fix

[shadowhand]

Just confirmed that this fix works. Thanks!