如何检索yelp category_filter与PHP?JSON对象中的JSON对象

Question

我正在使用Yelp API v1，我试图获得存储在类别对象中的category_filter。我的JSON的一小部分看起来像这样:

"businesses": [
{
 "address1": "800 N Point St",
 "phone": "4157492060",
 "categories": [{
"category_filter": "newamerican",
"search_url": "http://www.yelp.com/search?cflt=newamericanu0026find_desc=u0026find_loc=800+N+Point+St%2C+San+Francisco+94109",
"name": "American (New)"
}],
 "name": "Gary Danko",
 }]

我的php脚本如下:

<?php
$yelpstring = file_get_contents("PATH TO JSON", true); 
$obj = json_decode($yelpstring, true);
foreach($obj['businesses'] as $business){
echo "Restaurant name: " . $business['name']."<br/>";
echo "Restaurant Type: " . $business['categories']['category_filter']."<br/>";
echo "Address 1: " . $business['address1']."<br/>";
echo "Phone: " . $business['phone'] ."<br/>";
echo "<hr>";
}
?>

我得到的名称，address1和电话，但不是category_filter我得到一个php错误，说:

"注意:file.php第12行未定义索引:category_filter "

我不明白我做错了什么

Answer 1

$business['categories']['category_filter']

是错误的

你必须使用:$business['categories'][0]['category_filter']

在你的json是"[{"这意味着有一个数组(/object，解码为关联数组)在另一个数组。