Accessing associative array element using another element in PHP

Question

I'm quite new to PHP and I'm not really sure how to ask this question. My data is like this (displayed in JSON for easy viewing but i actually use array)

[{"_id":"1","title":"Month & Year","description":"To be used in Jurisprudence"},
 {"_id":"3","title":"Bible Version I","description":"Testament - Book - Chapter"}]

I know in PHP that i can access elements of associative array by using foreach as well as using the standard for loop.

e.g:

for($n=0;$n<sizeof($array_data);$n++){
     echo $array_data[$n]['title'];
}

Instead of using the index, what i want to do if possible is to access title using the _id. Something like, if have 3 as _id it should display the corresponding title in that array which is Bible Version I.

You have the tag associative-array, but your array is not associative. — Barmar
– Barmar, Commented Aug 5, 2017 at 18:44

Barmar · Accepted Answer · 2017-08-05 18:45:53Z

2

Use an if statement.

foreach ($array_data as $item) {
    if ($item['_id'] == 3) {
        echo $item['title'];
        break;
    }
}

If you'll be doing this a lot, you should probably change your array to an associative array, so you can then just use $array_data[3]. E.g. it should be:

{
    "1": {"_id":"1","title":"Month & Year","description":"To be used in Jurisprudence"},
    "3": {"_id":"3","title":"Bible Version I","description":"Testament - Book - Chapter"}
}

edited Aug 5, 2017 at 18:45

answered Aug 5, 2017 at 18:35

Barmar

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10 Comments

cattarantadoughan Over a year ago

Hi, thank you for your answer. But can i do it without using a loop? The thing is, i'm saving the _id as value in an html element. Since i have the array already loaded in the browser i just want to call the particular title via the _id saved. I already used the loop for loading the data in the html elements thus i dont want to iterate again using another one.

Barmar Over a year ago

No, you can't do it without a loop unless you change the array to an associative array first.

Jonathan Over a year ago

@ReubenJaMesAveñoGruta whatever you do, you need to loop. If you're searching an array, you have no choice

Barmar Over a year ago

Looping every time will be expensive. That's why you should use the associative array, accessing these elements is very efficient. If you have that many items you should probably be using a database.

Barmar Over a year ago

Or when you fetch the data fromthe database, you can do $array_data[$row['_id']] = $row; to create an associative array from the table.

|

Fawaz · Accepted Answer · 2017-08-05 19:09:58Z

1

A more efficient solution without a loop would be to use array_search with array_column :

$key = array_search("3", array_column($array_data, '_id'));
if ($myArray[$key]) {
  echo $myArray[$key]['_id'] . ' : ' . $myArray[$key]['title'];
}

Uses php 5.5.0 or above. Refer here

edited Aug 5, 2017 at 19:09

answered Aug 5, 2017 at 19:03

Fawaz

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3 Comments

Barmar Over a year ago

This is TWO loops, one loop to get all the column values, a second loop to search it for the ID you want.

Barmar Over a year ago

The loops are hidden inside the array_column and array_search functions, but they're still there.

Fawaz Over a year ago

@Barmar Are you sure ? Can you point to any doc or ref if array_column or array_search are loops ?

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