fputcsv $fields parameter should be array of strings

[DaveLiddament]

I think the fields parameter for fputcsv should be an array of strings. See PHP manual.

This snippet should report an error on line 22.

Running the code in the snippet on PHP 8.0 (PHP 8.0.0 (cli) (built: Dec 6 2020 06:56:11) ( NTS )) results in this error:

PHP Fatal error:  Uncaught Error: Object of class Person could not be converted to string in /home/vagrant/example/csv.php:24
Stack trace:
#0 /home/vagrant/example/csv.php(24): fputcsv()
#1 {main}
  thrown in /home/vagrant/example/csv.php on line 24

NOTE: I've seen a similar error with PHP 7.3 too.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/2478131ecf

<?php declare(strict_types = 1);

$handle = fopen("/tmp/output.csv", "w");
if ($handle === false) die();

class Person {}

class PersonWithToString {
	public function __toString(): string {
		return "to string name";
	}
}

class StringablePerson implements Stringable {
	public function __toString(): string {
		return "stringable name";
	}	
}

fputcsv($handle, [
	"string", // OK
	new Person, // ERROR: Person can not be converted to a string.
	new PersonWithToString, // OK
	new StringablePerson, // OK
]);

fclose($handle);

Psalm output (using commit b7792ab):

No issues!

[DaveLiddament]

See also: phpstan/phpstan-src#448

[orklah]

Indeed, the function is documented as array. However, please consider allowing int or floats too at least. They can be casted to a string without any issue

[DaveLiddament]

Good point @orklah

As a starting point for a test case I've created another snippet .

I only raise this as I was caught out when I changed a string to a value object and my CSV generation failed. PHPStan didn't flag this as an issue, and nor would have have Psalm.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/45dc241a38

<?php declare(strict_types = 1);

$handle = fopen("/tmp/output.csv", "w");
if ($handle === false) die();

class Person {}

class PersonWithToString {
	public function __toString(): string {
		return "to string name";
	}
}

class StringablePerson implements Stringable {
	public function __toString(): string {
		return "stringable name";
	}	
}

// All there are OK. Are there any other types that can be cast to a string?
fputcsv($handle, [
	"string",
    1,
    3.5,
    true,
    false, 
	new PersonWithToString,
	new StringablePerson,
]);

// THis is a problem
fputcsv($handle, [
	new Person, // ERROR, Should report this as an error
]);


fclose($handle);

Psalm output (using commit b7792ab):

No issues!

[DaveLiddament]

null also works.... So here in updated snippet

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/58b7ab935a

<?php declare(strict_types = 1);

$handle = fopen("/tmp/output.csv", "w");
if ($handle === false) die();

class Person {}

class PersonWithToString {
	public function __toString(): string {
		return "to string name";
	}
}

class StringablePerson implements Stringable {
	public function __toString(): string {
		return "stringable name";
	}	
}

// All there are OK. Are there any other types that can be cast to a string?
fputcsv($handle, [
	"string",
    1,
    3.5,
    true,
    false, 
    null,
	new PersonWithToString,
	new StringablePerson,
]);

// THis is a problem
fputcsv($handle, [
	new Person, // ERROR, Should report this as an error
]);


fclose($handle);

Psalm output (using commit b7792ab):

No issues!