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Patrique Ouimet

Developer

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Suppressing PHP Psalm Errors

Mon, Dec 16, 2019 8:42 AM

Recently I've been tickering with writing a routing package. While writing it I ran into issues where I need to explicitly check for 3 types for a single parameter. Here's the code snippet:

<?php

// Removed most of the code/comments to demonstration purposes.

/**
 * @param  null|array|object $data
 * @return static
 * @throws InvalidArgumentException
 */
public function withParsedBody($data)
{
    if (! is_null($data) && ! is_object($data) && ! is_array($data)) {
        throw new InvalidArgumentException(
            'Parsed body must be of type: null, array, or object'
        );
    }
    // more code here...
}

The above block of code would give me the following error from Psalm:

ERROR: TypeDoesNotContainType - src/ServerRequest.php:756:13 - Found a contradiction when evaluating $data and trying to reconcile type 'array<array-key, mixed>' to !array
        if (! is_null($data) && ! is_object($data) && ! is_array($data)) {


ERROR: TypeDoesNotContainType - src/ServerRequest.php:756:57 - Found a contradiction when evaluating $data and trying to reconcile type 'array<array-key, mixed>' to !array
        if (! is_null($data) && ! is_object($data) && ! is_array($data)) {

I tried a few different solutions to solve the issues described, nothing seemed to work.

Solution

After reading through PHP Psalm documentation (Dealing with code issues) I figured out I could suppress certain errors for a block of code.

<?php

// Removed most of the code/comments to demonstration purposes.

/**
 * @param  null|array|object $data
 * @return static
 * @throws InvalidArgumentException
 */
public function withParsedBody($data)
{
    /**
     * @psalm-suppress DocblockTypeContradiction
     * @psalm-suppress TypeDoesNotContainType
     */
    if (! is_null($data) && ! is_object($data) && ! is_array($data)) {
        throw new InvalidArgumentException(
            'Parsed body must be of type: null, array, or object'
        );
    }
    // more code here...
}

If you happen to know why I'm getting this error message and how to fix it (without suppressing psalm errors) please let me know! Send me an email at patrique.ouimet@gmail.com or send me a direct message on Twitter @patoui2.

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