PHP - compare the structure of two JSON objects - php

Question

I have two JSON objects and I would like to compare their structure. How can I do it?
Those object are being generated on-the-fly and depending on dynamic content.
Which means that the objects are always different but most of the time have the same structure. I want to be able to catch the changes once they occur.
Example: These two objects should be considered as equal, because both have the same structure: index var and tags array.
{
"index": 0,
"tags": [
"abc"
]
}
{
"index": 1,
"tags": [
"xyz"
]
}
Thoughts?

Answer 1

## You can use this library TreeWalker php .##
TreeWalker is a simple and smal API in php
(I developed this library, i hope it helps you)
It offers two methods
1- Get json difference
2- Edit json value (Recursively)
this method will return the diference between json1 and json2
$struct1 = array("casa"=>1, "b"=>"5", "cafeina"=>array("ss"=>"ddd"), "oi"=>5);
$struct2 = array("casa"=>2, "cafeina"=>array("ss"=>"dddd"), "oi2"=>5);
//P.s
print_r($treeWalker->getdiff($struct1, $struct2))
{
new: {
b: "5",
oi: 5
},
removed: {
oi2: 5
},
edited: {
casa: {
oldvalue: 2,
newvalue: 1
},
cafeina/ss: {
oldvalue: "dddd",
newvalue: "ddd"
}
},
time: 0
}

Answer 2

It's a bit rough, but you get the picture;
$json = '[
{
"index": 0,
"tags": [
"abc"
]
},
{
"index": 1,
"tags": [
"xyz"
]
},
{
"foo": 2,
"bar": [
"xyz"
]
}]';
$array = json_decode($json, true);
$default = array_keys($array[0]);
$error = false;
$errors = array();
foreach ($array as $index => $result):
foreach ($default as $search):
if (!isset($result[$search])):
$error = true;
$errors[] = "Property '{$search}' at entry '{$index}' not found. ";
endif;
endforeach;
endforeach;
if ($error):
echo 'Objects are not the same. ';
foreach ($errors as $message):
echo $message;
endforeach;
endif;
returns:
Objects are not the same. Property 'index' at entry '2' not found. Property 'tags' at entry '2' not found.

Answer 3

You can try to use package https://github.com/coduo/php-matcher
Example: These two objects should be considered as equal, because both have the same structure: index var and tags array.
You can create a "php-matcher pattern" like this:
{
"index": "#integer#",
"tags": "#array#.repeat(\"#string#\")"
}
Then you match your JSONs against this pattern. If you have 2 JSONs and both match this pattern then it means that they are "equal" according to your definition of equality above.
Please see results in "php-matcher sandbox" for the example JSONs you gave:
Example 1 in sandbox
Example 2 in sandbox
Additionally you can use package https://github.com/sebastianbergmann/diff (which you should already have if you have phpunit) to generate a diff when the pattern doesnt match the value.
For example:
use SebastianBergmann\Diff\Differ;
use SebastianBergmann\Diff\Output\UnifiedDiffOutputBuilder;
...
$valueToCheck = '{
"foo": 0,
"bar": {"one": 1, "two": "2"}
}';
$expectedValuePattern = '{
"foo": "#integer#",
"bar": {"one": 1, "two": 2}
}';
if (!$matcher->match($valueToCheck, $expectedValuePattern)) {
$differ = new Differ(
new UnifiedDiffOutputBuilder(
"Json value is not matching expected format:\n",
true
)
);
$diffOutput = $differ->diff(
\json_encode(\json_decode($expectedValuePattern, true), JSON_PRETTY_PRINT),
\json_encode(\json_decode($valueToCheck, true), JSON_PRETTY_PRINT)
);
var_dump(
$diffOutput
. "\n".$matcher->getError()."\n"
);
} else {
var_dump('OK');
}
it will print:
Json value is not matching expected format:
## -1,7 +1,7 ##
{
- "foo": "#integer#",
+ "foo": 0,
"bar": {
"one": 1,
- "two": 2
+ "two": "2"
}
}
That message with diff is especially helpfull for bigger JSON's to quickly see which element is not matching.
See more ways of usage in README of that package - especially:
https://github.com/coduo/php-matcher#json-matching
https://github.com/coduo/php-matcher#json-matching-with-unbounded-arrays-and-objects
This package is very good to use in automatic tests (for example: phpunit) to assert if JSON from API responses is correct etc - considering that in integration tests there are often many id's, uuid's, datetime's etc which change on each test execution - like database generated id's etc.
I hope it helps :)

Answer 4

You mean by structure, like model array like:
array ( 'index' => int, 'tags' => array() )
If that's what you are trying to get, try this...
$arr1 = array (
array (
'index' => 0,
'tags' => ['abc']
),
array (
'index' => 1,
'tags' => ['xyz']
),
array (
'index' => 2,
'tags' => ['xyz'],
'boom' => 'granade'
),
array (
'index' => 3,
'tags' => 'xyz'
)
);
$holder = array();
$model = array ('index' => 0, 'tags' => array());
for ($i = 0;$i < count($arr1); $i++)
{
$holder = array_diff(array_merge_recursive($arr1[$i], $model), $model);
if (!empty($holder))
{
echo "different structure<br>";
}
else
{
echo "same structure<br>";
// for further validation
/*
$keys = array_keys($model);
if (is_int($arr1[$i][$keys[0]]) && is_array($arr1[$i][$keys[1]]))
echo "same structure<br>";
else
echo "different structure<br>";
*/
}
}
Sample output:
same structure
same structure
different structure
different structure

Answer 5

You can convert the json string to a php array then use the array_diff($arr1,$arr2) function to compare the newly created array with another array
the result is an array containing the elements of the first array that doesn't exist in the other array
example :
<?php
$array1 = '{"name":"myname","age":"40"}';
//convert the obtained stdclass object to an array
$array1 = (array) json_decode($array1);
$array2 = array("name"=>"myname123","age"=>10);
print_r($array2);
$result_array = array_diff($array1,$array2);
if(empty($result_array[0])){
echo "they have the same structure ";
}
?>