Question

我刚开始使用python和flask（对于raspberry pi）。我想要一个Web应用程序来执行一些python代码来平移和倾斜摄像机并显示视频流。

我现在对于烧瓶的代码是：

from flask import Flask, render_template
import time
import serial
#ser = serial.Serial('/dev/ttyUSB0',9600)
app = Flask(__name__)
@app.route('/')
@app.route('/<cmd>') #each button in my html redirects to a specified directory
def execute(cmd=None):
if cmd == "down":
    print "Moving Down"
    #ser.write("D")

if cmd == "up":
    print "Moving Up"
    #ser.write("U")

if cmd == "left":
    print "Moving Left"
   # ser.write("L")

if cmd == "right":
    print "Moving Right"
    #ser.write("R")

if cmd == "reset":
    print "Reseting.."
    #ser.write("X")
return render_template("main.html")


if __name__ == "__main__":
app.run(host='0.0.0.0', port=8080, debug=True)

问题是我的代码依赖于每个按钮重定向到新的directry，虽然这确实很好，每次刷新页面，这意味着我的嵌入视频重新加载和缓冲。是否有更好的方法来检测按钮然后使用烧瓶执行python代码？

Answer 1

我会把它拆分成两条路线，以便更容易看到你必须做的事情：

LEFT, RIGHT, UP, DOWN, RESET = "left", "right", "up", "down", "reset"
AVAILABLE_COMMANDS = {
    'Left': LEFT,
    'Right': RIGHT,
    'Up': UP,
    'Down': DOWN,
    'Reset': RESET
}

@app.route('/')
def execute():
    return render_template('main.html', commands=AVAILABLE_COMMANDS)

@app.route('/<cmd>')
def command(cmd=None):
    if cmd == RESET:
       camera_command = "X"
       response = "Resetting ..."
    else:
        camera_command = cmd[0].upper()
        response = "Moving {}".format(cmd.capitalize())

    # ser.write(camera_command)
    return response, 200, {'Content-Type': 'text/plain'}

然后在您的模板中，您只需使用一些JavaScript发送请求：

{# in main.html #}
{% for label, command in commands.items() %}
    <button class="command command-{{ command }}" value="{{ command }}">
        {{ label }}
    </button>
{% endfor %}

{# and then elsewhere #}
<script>
// Only run what comes next *after* the page has loaded
addEventListener("DOMContentLoaded", function() {
  // Grab all of the elements with a class of command
  // (which all of the buttons we just created have)
  var commandButtons = document.querySelectorAll(".command");
  for (var i=0, l=commandButtons.length; i<l; i++) {
    var button = commandButtons[i];
    // For each button, listen for the "click" event
    button.addEventListener("click", function(e) {
      // When a click happens, stop the button
      // from submitting our form (if we have one)
      e.preventDefault();

      var clickedButton = e.target;
      var command = clickedButton.value;

      // Now we need to send the data to our server
      // without reloading the page - this is the domain of
      // AJAX (Asynchronous JavaScript And XML)
      // We will create a new request object
      // and set up a handler for the response
      var request = new XMLHttpRequest();
      request.onload = function() {
          // We could do more interesting things with the response
          // or, we could ignore it entirely
          alert(request.responseText);
      };
      // We point the request at the appropriate command
      request.open("GET", "/" + command, true);
      // and then we send it off
      request.send();
    });
  }
}, true);
</script>

Answer 2

我遇到了同样的问题，使用ajax XmlHttpRequest答案很简单：

// send a request, but don't refresh page
xhttp = new XMLHttpRequest();
xhttp.open("GET", "your script action", true);
xhttp.send();

这是一个小例子，使用参数“like”调用当前脚本，嵌入函数中：

function likeStuffs()
{
    // send a request, but don't refresh page
    xhttp = new XMLHttpRequest();
    xhttp.open("GET", "?like", true);
    xhttp.send();
}

Answer 3

你可以在AJAX的帮助下完成这个...这是一个调用python函数的例子，它打印你好而不重定向或刷新页面。

在app.py中放置代码段。

//rendering the HTML page which has the button
@app.route('/json')
def json():
    return render_template('json.html')

//background process happening without any refreshing
@app.route('/background_process_test')
def background_process_test():
    print "Hello"
    return "nothing"

您的json.html页面应如下所示。

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type=text/javascript>
        $(function() {
          $('a#test').bind('click', function() {
            $.getJSON('/background_process_test',
                function(data) {
              //do nothing
            });
        return false;
      });
    });
</script>


//button
<div class='container'>
<h3>Test</h3>
    <form>
        <a href=# id=test><button class='btn btn-default'>Test</button></a>
    </form>

</div>

这里当您在控制台中按下“简单测试”按钮时，您可以看到＆＃34; Hello＆＃34;显示没有任何刷新。

Flask Button运行Python而不刷新页面？

3 个答案: