Add support for type coercion #308

shmax · 2016-09-15T05:52:09Z

For people (like myself) that use JSON Schema to validate API requests, a common problem is handling values that come across HTTP as strings:

$query = http_build_query([
   'processRefund'=>true,
   'refundAmount'=>17
]);

echo $query; // processRefund=true&refundAmount=17;

parse_str($query);
echo $processRefund; // "true" (a string value)
echo $refundAmount; // "17" (also a string value).

This will of course fail a json schema definition expecting booleans and numbers.

This change adds a new CHECK_MODE_COERCE mode that goes one step further than CHECK_MODE_TYPE_CAST by forcing strings to their expected types when appropriate in the original object so it can then be used naturally by the consuming client code.

$request = (object)[
   'processRefund'=>"true",
   'refundAmount'=>"17"
];

$checkMode = \JsonSchema\Constraints\Constraint::CHECK_MODE_COERCE | JsonSchema\Constraints\Constraint::CHECK_MODE_TYPE_CAST;
$validator = new \JsonSchema\Validator($checkMode);
$validator->check($request, (object) [
    "type"=>"object",
    "properties"=>[
        "processRefund"=>[
            "type"=>"boolean"
        ],
        "refundAmount"=>[
            "type"=>"number"
        ]
    ]
]); // validates!

is_bool($request->processRefund); // true
is_int($request->refundAmount); // true

This is a feature you see in some other validation libraries (https://github.com/geraintluff/jsv4-php, https://github.com/epoberezkin/ajv ), but if you guys aren't interested it's not a problem--I really have to compliment the injection model you've developed. It would be just as easy for me to add this functionality to my own sub-classes.

shmax · 2016-09-19T00:06:38Z

Thoughts? Comments? Suggestions?

bighappyface

Tests please

shmax · 2016-09-20T04:02:54Z

@bighappyface Added tests. Thank you, that was a helpful exercise, and it prompted some further refinement:

added casting for the integer type
I've modified the mode member to be a bit mask, int/number/boolean casting is now triggered by the CHECK_MODE_TYPE_CAST flag, and CHECK_MODE_COERCE just allows the write to the input (because someone might want to allow the looser type checking, but not actually coerce the result).

shmax · 2016-09-24T13:12:20Z

Please review, folks.

bighappyface · 2016-09-24T15:25:50Z

src/JsonSchema/Constraints/Constraint.php

@@ -28,8 +28,9 @@
    protected $errors = array();
    protected $inlineSchemaProperty = '$schema';

-    const CHECK_MODE_NORMAL = 1;
-    const CHECK_MODE_TYPE_CAST = 2;
+    const CHECK_MODE_NORMAL = 0x00000001;


Why hex literals?

Just a style thing I learned decades ago. I guess the idea is that this way it's a little more clear to the reader that we're creating a sequence for the purpose of bit-masking (and you don't have to get out a calculator to figure out what the higher numbers are, though it's not an issue in this simple case).

0x00000001 0x00000002 0x00000004 0x00000008 0x00000010 0x00000020 0x00000040

vs

1 2 4 8 16 32 64

But I could go either way if you feel strongly about it.

I'm fine with it but I would caution that web developers, in my experience, are not usually accustomed to bitwise operations or thinking.

would go with a boolean literal if that is the clarity you intend to convey:

0b0000001 // 1 0b0000010 // 2 0b0000100 // 4

Went with binary literals.

bighappyface · 2016-09-24T15:28:00Z

src/JsonSchema/Constraints/ObjectConstraint.php

+    protected function toInteger($value)
+    {
+        if(ctype_digit ($value)) {
+            return $value + 0; // cast to number


Why not cast instead of coerce here?

Can you explain what it is you have in mind in a bit more detail, please? This is a cast (in the case that a string is input). The actual coercing happens (optionally) in lines 136 and 138 of this file.

I am referring to an explicit cast instead of an operation that results in an implicit cast:

return (int) $value;

For the toNumber method it makes sense to use the operation to produce an integer or a float, but for a whole number simply casting to the desired type is more expressive, in my opinion.

I see no problem with that. Changed.

bighappyface · 2016-09-24T15:28:21Z

src/JsonSchema/Constraints/ObjectConstraint.php

+                case "boolean":
+                    $value = $this->toBoolean($value);
+                    break;
+


bighappyface · 2016-09-24T15:28:32Z

src/JsonSchema/Constraints/ObjectConstraint.php

@@ -146,6 +232,7 @@ protected function getProperty($element, $property, $fallback = null)
        if (is_array($element) /*$this->checkMode == self::CHECK_MODE_TYPE_CAST*/) {
            return array_key_exists($property, $element) ? $element[$property] : $fallback;
        } elseif (is_object($element)) {
+


shmax · 2016-09-26T00:07:43Z

@bighappyface I had to go back to the hex literals; the binary integer literals aren't supported until PHP 5.4 , so the tests were failing. Hope that's not a problem.

http://fr2.php.net/manual/en/language.types.integer.php

shmax · 2016-09-29T02:56:49Z

So what happens now?

shmax · 2016-10-05T16:25:28Z

@bighappyface Hey there, I submitted this PR 3 weeks ago, now. I'm not really complaining, but I was just curious what the merge process is? Are we waiting for someone or something? I have another small change I'd like to submit, but if this is a dead project I don't want to waste the effort. Let me know! Thanks...

shmax · 2016-10-09T19:50:39Z

Thanks much! 👍

add support for type coercion

aa72e28

bighappyface requested changes Sep 19, 2016

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bighappyface added the Needs Tests label Sep 19, 2016

shmax added 4 commits September 19, 2016 19:20

add tests

1e0942e

move coerce tests out of base

0eded5b

use flags for mode

bfd0611

update readme

aa771b9

fix tests

1ddebe7

bighappyface reviewed Sep 24, 2016

View reviewed changes

remove ws

b7afe7a

bighappyface added Needs Review and removed Needs Tests labels Sep 24, 2016

shmax added 2 commits September 24, 2016 14:36

use binary literals, explicit cast

75a200b

back to hex

ff07d71

shmax mentioned this pull request Oct 3, 2016

performance improvements #310

Merged

bighappyface approved these changes Oct 9, 2016

View reviewed changes

bighappyface merged commit a918d3b into justinrainbow:master Oct 9, 2016

shmax deleted the add-coercion-support branch October 9, 2016 19:50

shmax mentioned this pull request Jan 13, 2017

Allow coercion to boolean from '0' and '1' #345

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Add support for type coercion #308

Add support for type coercion #308

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Add support for type coercion #308

Add support for type coercion #308

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