Php 我在json api wordpress中的json输出得到了不需要的null

我是wordpress新手，在wordpress中为web服务使用Json Api，我在

Json Api/controllers/core.php

文件中创建了自己的服务。我的功能是：

<?php
public function get_blogs(){
global $json_api;
$categories = $json_api->introspector->get_categories($args);
echo  "[";
foreach($categories as $cat){
if($cat->id == "5432"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5433"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5439"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5444"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5440"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5438"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5430"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
 if($cat->id == "5435"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5436"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5434"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5441"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5445"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5431"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5437"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "203"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}".",";
}
if($cat->id == "5442"){
 $catPost = get_posts('cat="$cat->id"&posts_per_page=4');
 echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
  $catnow = json_encode($catPost);
  echo $catnow;
  echo "}".",";
  }
  if($cat->id == "5447"){
  $catPost = get_posts('cat="$cat->id"&posts_per_page=4');
  echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
  $catnow = json_encode($catPost);
  echo $catnow;
  echo "}".",";
  }
  if($cat->id == "530"){
  $catPost = get_posts('cat="$cat->id"&posts_per_page=4');
  echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
  $catnow = json_encode($catPost);
  echo $catnow;
   echo "}".",";
  }
  if($cat->id == "5443"){
  $catPost = get_posts('cat="$cat->id"&posts_per_page=4');
  echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
  $catnow = json_encode($catPost,JSON_PRETTY_PRINT);
  echo $catnow;
  echo "}".",";
  }
if($cat->id == "5448"){
$catPost = get_posts('cat="$cat->id"&posts_per_page=4');
echo "{"."\"category_title\":\"$cat->title\"".",\"category_id\":\"$cat->id\"".",\"posts\":";
$catnow = json_encode($catPost);
echo $catnow;
echo "}";
}

}
echo  "]";
  }

---

在您发布的文件之后，很可能还有另一个文件正在运行，该文件负责回显
null
。这是值得研究的

话虽如此，与其尝试格式化自己的JSON输出，不如创建数据对象，然后使用
JSON\u encode（）
对其进行编码

例如，以代码的最后一块为例，它看起来

if($cat->id == "5448"){
    $catPost = get_posts('cat="$cat->id"&posts_per_page=4');
    echo json_encode(array(
      "category_title" => $cat->title,
      "category_id" => $cat->id,
      "posts" => $catPost
    ));
}

如果整个内容都是以这种形式编写的，那么应该消除任何格式错误