php - 调用未定义的 PHP 函数 : tried everything i can think of

Question

我查看了所有通常存在问题的内容。也许我正在密切关注。谁能告诉是什么使“checkLocationExists”函数未定义？我已经检查了括号、';'s、包含、打开和关闭 php 标签(此处未显示关闭标签，它位于文件末尾。

<?php

require_once 'DBOperations.php';

class Functions{

private $db;

public function __construct() {
  $this -> db = new DBOperations();
}

public function searchPosts($rawLocation){
  $db = $this -> db;
  $locationArr = explode(",", $rawLocation);
  $formattedCity = $locationArr[0];
  $formattedState = $locationArr[1];
  echo 'String parameters for getLocationID are: 
'.$formattedCity.','.$formattedState.'.';
  if (checkLocationExists($formattedCity, $formattedState)){
      $locationID = $db -> getLocationID($formattedCity,
$formattedState);
      echo $locationID.'...is the locationId returned by "$db
>getLocationID()"';
      $response = $db -> getPostsByLocation($locationID);
      return json_encode($response);
  }else {
    $response['message'] = 'Location not in database, select one from
the AutoComplete drop down.';
    json_encode($response);
  }
}
public function checkLocationExists($city, $state) {
  $db = $this -> db;
  if ($db -> checkCity($city) && $db -> checkState($state) ) {
    return true;
  } else {
    return false;
    }
}

Answer 1

您应该修改代码以编写 $this->checkLocationExists() 而不是 checkLocationExists()，因为您正在调用类函数。

也请不要写 $db -> abcd ，而是写 $db->abcd 因为这样看起来更具可读性。避免箭头前后的空格。