PHP - get value from JSON - php

Question

Before i decode my JSON i get this result:
{
"1":[{"membership_id":1,"group_id":1,"user_id":1},
"2":[{"membership_id":3,"group_id":1,"user_id":2}
}
How would i specify that i want to select the one who has 'user_id' == 2 and return membership_id value?
My attempt, but i get undefined value 'user_id':
$myjson = json_decode($s_o, true);
foreach ($myjson as $key => $value){
if($value['user_id'] == $cid){
$mid = $value['membership_id'];
}
}
echo $mid;
Basically i guess i would first have to select the right object and go through it with the foreach, but here i got a bit lost in the situation.

Answer 1

Use Array-Functions:
$json = '{
"1":[{"membership_id":1,"group_id":1,"user_id":1}],
"2":[{"membership_id":3,"group_id":1,"user_id":2}]
}';
$array = json_decode($json, true);
$searchUserID = 2;
$filteredArray = array_filter($array, function($elem) use ($searchUserID){
return $searchUserID == $elem[0]['user_id'];
});
$mid = array_column(array_shift($filteredArray), 'membership_id')[0];
echo "Membership-ID: ".$mid;
array_filter uses a callback function that iterates over every element of the array. If the callback function returns true, that element is assigned to $filteredArray. No need for a foreach loop that way.
But the return value is the whole array element:
Array
(
[2] => Array
(
[0] => Array
(
[membership_id] => 3
[group_id] => 1
[user_id] => 2
)
)
)
So you have to extract your membership_id.
Read the following line from inside out.
First, we fetch the first entry of the array with array_shift (since we have only one entry, this will be our desired entry).
Array
(
[0] => Array
(
[membership_id] => 3
[group_id] => 1
[user_id] => 2
)
)
We pass this array on to array_column to find the entry in the encapsulated array with the column name membership_id. Since array_column again returns an array,
Array
(
[0] => 3
)
we get the (one and only) entry by adding [0] to the end of this command.
Since the last part is a little complicated, here's a torn apart version of it:
$firstEntryOfFilteredArray = array_shift($filteredArray);
$arrayWithValueOfColumnMembershipID = array_column($firstEntryOfFilteredArray, 'membership_id');
$membership_id = $arryWithValueOfColumnMembershipID[0];
These three lines are concatenated into this:
$mid = array_column(array_shift($filteredArray), 'membership_id')[0];
here's a working example: http://sandbox.onlinephpfunctions.com/code/8fe6ede71ca1e09dc68b2f3bec51743b27bf5303

Answer 2

I'm assuming the JSON actually looks like:
{
"1":[{"membership_id":1,"group_id":1,"user_id":1}],
"2":[{"membership_id":3,"group_id":1,"user_id":2}]
}
Each element of the object is an array for some reason. So you need to index it with $value[0] to access the object contained inside it.
$myjson = json_decode($s_o, true);
foreach ($myjson as $key => $value){
if($value[0]['user_id'] == $cid){
$mid = $value[0]['membership_id'];
break;
}
}
echo $mid;
If the arrays can contain multiple elements, you'll need nested loops.
$myjson = json_decode($s_o, true);
foreach ($myjson as $key => $value){
foreach ($value as $object) {
if($object['user_id'] == $cid){
$mid = $object['membership_id'];
break 2;
}
}
}
echo $mid;

Answer 3

This is a bit speculative, but I think the data is indexed by user ID. If that's the case, it makes the lookup much simpler.
After decoding with $myjson = json_decode($s_o, true);
Just find the record by ID and get the membership_id from the matching row.
$membership_id = reset($myjson['2'])['membership_id'];`
You should probably verify that that ID exists, so maybe something like:
$membership_id = isset($myjson['2']) ? reset($myjson['2'])['membership_id'] : null;
If I'm wrong and the fact that the row numbers match the user_id is just a coincidence, then never mind :)