无法使用 NodeMCU 向服务器发送 POST 请求

Question

我有一个用 Arduino 语言编程的 NodeMCU。我正在尝试将一些数据从我的传感器发送到我服务器上的 PHP 脚本，然后将数据写入 MySQL 服务器。当通过 URL 运行时，脚本运行良好，但是当我尝试从我的代码中发送值时，我得到了这个错误

200 插入传感器（温度、光线） VALUES ('', '')
SQLSTATE[HY000]：一般错误：1366 不正确的整数值：第 1 行的列 'temp' 的''

现在我知道这是因为没有数据发送到 PHP 脚本，并且空格不是整数。

这是 NodeMCU 上的代码

#include <ESP8266HTTPClient.h>
#include <ESP8266WiFi.h>

void setup() {

  Serial.begin(115200);                                  //Serial connection
  WiFi.begin("ssid", "password");   //WiFi connection

  while (WiFi.status() != WL_CONNECTED) {  //Wait for the WiFI connection completion

    delay(500);
    Serial.println("Waiting for connection");

  }

}

void loop() {

 if(WiFi.status()== WL_CONNECTED){   //Check WiFi connection status

   HTTPClient http;    //Declare object of class HTTPClient

   http.begin("http://server_public_ip_address/test3.php");      //Specify request destination
   http.addHeader("Content-Type", "text/plain");  //Specify content-type header

   int httpCode = http.POST("?temp=20&light=88");   //Send the request
   String payload = http.getString();                  //Get the response payload

   Serial.println(httpCode);   //Print HTTP return code
   Serial.println(payload);    //Print request response payload

   http.end();  //Close connection

 }else{

    Serial.println("Error in WiFi connection");   

 }

  delay(3000);  //Send a request every 30 seconds

}

我怀疑问题出在http.addHeader("Content-Type", "text/plain"); 或int httpCode = http.POST("?temp=20&light=88"); 行中。

另外，这只是一个测试程序。最终程序将在这一行 int httpCode = http.POST("?temp=20&light=88"); 中使用变量而不是数字。那我该怎么写呢？

编辑：
也添加 PHP 脚本

<?php
$servername = "localhost";
$username = "root";
$password = "*************";
$dbname = "testbox1";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $temp = $_GET["temp"];
    $light = $_GET["light"];
    $sql = "INSERT INTO sensor (temp, light)
    VALUES ('$temp', '$light')";
    // use exec() because no results are returned
    $conn->exec($sql);
    echo "New record created successfully";
    }
catch(PDOException $e)
    {
    echo $sql . "<br>" . $e->getMessage();
    }

$conn = null;
?>

Answer 1

你过去了

http.POST("?temp=20&light=88")

应该是这样的

http.POST("temp=20&light=88")

和标题

http.addHeader("Content-Type", "text/plain")

基本上是用来发送纯文本的，可以参考这里的content-type header的docs。因为，您正在发送表单数据，所以应该使用它

http.addHeader("Content-Type", "application/x-www-form-urlencoded")

以下代码应该可以解决您的问题。

#include <ESP8266HTTPClient.h>
#include <ESP8266WiFi.h>

void setup() {

  Serial.begin(115200);                                  //Serial connection
  WiFi.begin("ssid", "password");   //WiFi connection

  while (WiFi.status() != WL_CONNECTED) {  //Wait for the WiFI connection completion

    delay(500);
    Serial.println("Waiting for connection");

  }

}

void loop() {

 if(WiFi.status()== WL_CONNECTED){   //Check WiFi connection status

   HTTPClient http;    //Declare object of class HTTPClient

   http.begin("http://server_public_ip_address/test3.php");      //Specify request destination
   http.addHeader("Content-Type", "application/x-www-form-urlencoded");  //Specify content-type header

   int httpCode = http.POST("temp=20&light=88");   //Send the request
   String payload = http.getString();                  //Get the response payload

   Serial.println(httpCode);   //Print HTTP return code
   Serial.println(payload);    //Print request response payload

   http.end();  //Close connection

 }else{

    Serial.println("Error in WiFi connection");   

 }

  delay(3000);  //Send a request every 30 seconds

}

将其用作您的 PHP 文件以查看发送的值：

<?php 
    print_r($_POST);
?>

问题在于您的 PHP 脚本。您必须使用 $_POST，而不是 $_GET。此外，您的 PDO 语法中有一个小错误。我试图修复它。检查这个：

<?php
$servername = "localhost";
$username = "root";
$password = "*************";
$dbname = "testbox1";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $temp = $_POST["temp"];
    $light = $_POST["light"];
    $sql = $conn->prepare("INSERT INTO sensor (temp, light) VALUES (?, ?)");
    $sql->bindParam(1, $temp);
    $sql->bindParam(2, $light);
    $sql->execute();
    echo "New record created successfully";
    }
catch(PDOException $e)
    {
    echo $sql . "<br>" . $e->getMessage();
    }
?>