Need help using array/json in php for coinmarketcap api

Question

I'm trying to make a simple website that uses the coinmarketcap api to track current cryptocurrency prices, and the code below works but it doesn't account for when currencies overtake each other.

    <?php
    $tick = file_get_contents('https://api.coinmarketcap.com/v1/ticker/');
    $url = $tick;
    echo $url;
    $json = file_get_contents($url);
    $data = json_decode($tick, TRUE); //decodes in associative array

    $ethusd = $data[1]['price_usd'];
    echo $ethusd;

    ?>

And this is the json being decoded

[
{
    "id": "bitcoin", 
    "name": "Bitcoin", 
    "symbol": "BTC", 
    "rank": "1", 
    "price_usd": "16474.4", 
    "price_btc": "1.0", 
    "24h_volume_usd": "13440600000.0", 
    "market_cap_usd": "275760451140", 
    "available_supply": "16738725.0", 
    "total_supply": "16738725.0", 
    "max_supply": "21000000.0", 
    "percent_change_1h": "-2.32", 
    "percent_change_24h": "-5.68", 
    "percent_change_7d": "24.41", 
    "last_updated": "1513187054"
}, 
{
    "id": "ethereum", 
    "name": "Ethereum", 
    "symbol": "ETH", 
    "rank": "2", 
    "price_usd": "684.996", 
    "price_btc": "0.04138", 
    "24h_volume_usd": "4731760000.0", 
    "market_cap_usd": "65976663404.0", 
    "available_supply": "96316859.0", 
    "total_supply": "96316859.0", 
    "max_supply": null, 
    "percent_change_1h": "-5.62", 
    "percent_change_24h": "12.04", 
    "percent_change_7d": "56.0", 
    "last_updated": "1513187055"
}, 
{
    "id": "bitcoin-cash", 
    "name": "Bitcoin Cash", 
    "symbol": "BCH", 
    "rank": "3", 
    "price_usd": "1594.38", 
    "price_btc": "0.0963151", 
    "24h_volume_usd": "1286400000.0", 
    "market_cap_usd": "26871042768.0", 
    "available_supply": "16853600.0", 
    "total_supply": "16853600.0", 
    "max_supply": "21000000.0", 
    "percent_change_1h": "-3.9", 
    "percent_change_24h": "1.8", 
    "percent_change_7d": "8.88", 
    "last_updated": "1513187076"
}, 
etc.

Since ether is the second highest currency in the json it works for now, but if it moves it wouldn't. So is there a way for me to do something like $data[something that specifies ether]['price_usd'] instead? Apologies in advance for any PHP ignorance, I know very little about PHP/arrays/etc and just started working with it a few days ago.

Possible duplicate of JSON data through JS/AJAX into PHP

Arun
– Arun

2017-12-14 20:36:56 +00:00
Commented Dec 14, 2017 at 20:36 — Arun
– Arun, Commented Dec 14, 2017 at 20:36

Flo · Accepted Answer · 2017-12-13 18:49:10Z

0

I played a little bit with their API and you can fetch only 1 currency by appending the slug of the currency in the url:

example https://api.coinmarketcap.com/v1/ticker/ethereum/

so your endpoint becomes https://api.coinmarketcap.com/v1/ticker/{slug}/

/!\ Be aware that this endpoint still sends you a JSON array so you have to take the first index with $data[0]. Your code becomes :

<?php
$slug = 'ethereum'; // find all at https://files.coinmarketcap.com/generated/search/quick_search.json
$tick = file_get_contents('https://api.coinmarketcap.com/v1/ticker/'.$slug.'/');
$url = $tick;
echo $url;
$json = file_get_contents($url);
$data = json_decode($tick, TRUE); //decodes in associative array

$ethusd = $data[0]['price_usd'];
echo $ethusd;

?>

All slugs are listed here https://files.coinmarketcap.com/generated/search/quick_search.json

PS: API docs are here https://coinmarketcap.com/api/ but it doesn't mention the slug endpoint

answered Dec 13, 2017 at 18:49

Flo

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1 Comment

Bryce Hoehn Over a year ago

Thank you, that was very helpful but I probably should have mentioned that Ethereum wasn't the only coin I was trying to fetch my bad. I got it working using YouneL's solution and just repeated the $key_x part for each coin I needed.

YouneL · Accepted Answer · 2017-12-13 18:56:46Z

0

What I understand here is that you want to get the price_usd only for ethereum id, to do so you can use array_columns to extract all ids as one array and then search the index of 'ethereum':

$key_ethereum = array_search('ethereum', array_column($data, 'id'));

// array_column($data, 'id') => ['bitcoin', 'ethereum', 'bitcoin-cash']
// array_search('ethereum', ['bitcoin', 'ethereum', 'bitcoin-cash']); => 1

echo $data[ $key_ethereum ]['price_usd'];

Live Demo

Hope this helps

edited Dec 13, 2017 at 18:56

answered Dec 13, 2017 at 18:50

YouneL

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2 Comments

Bryce Hoehn Over a year ago

Worked perfectly thank you! Ethereum wasn't the only coin I was trying to get price_usd for but I just repeated the $key_x for each coin I needed and it worked.

YouneL Over a year ago

You are welcome, you may want to accept my answer if it works for you.

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