在AMP中如何检查响应是否为空？需验证表单提交成功后的event.response.redirect

Hey there! Let's break down how to address your two AMP form questions clearly.

1. Check for event.response.redirect on Submit-Success #

Your current form uses AMP.navigateTo directly when the submit succeeds, but we can add a conditional check to only run the navigation if redirect exists in the response. Here's how to modify your form:

<form class="proceed__form" id="proceed__form" method="post" action-xhr="@addtocartlink" target="_top" 
  on="submit-success: 
    if(event.response.redirect) {
      AMP.navigateTo(url: event.response.redirect);
    } else {
      // Add your fallback logic here (e.g., show a message to the user)
      AMP.setState({ cartStatus: 'Item added successfully, but no redirect URL was provided.' });
    }">
  <input type="submit" style="font-size:16px;" value="Add To Cart" />
  <!-- Optional: Display status message -->
  <p [text]="cartStatus" class="status-message"></p>
</form>

What's happening here: #

• We wrap the AMP.navigateTo call in an if statement that checks if event.response.redirect exists and has a valid value.
• If the redirect URL isn't present, we use AMP.setState to update a state variable, which can then display a fallback message to the user (you can adjust this logic to fit your needs, like showing an alert or updating other UI elements).

2. Check if the Response is Empty #

In AMP, you can check for empty responses by verifying if event.response exists and whether it contains any meaningful data. There are two common scenarios to handle:

Scenario 1: No response object at all (null/undefined) #

If the server returns no response, event.response will be null or undefined. You can check this with a simple negation:

on="submit-success: 
    if(!event.response) {
      AMP.setState({ errorMessage: 'No response received from the server.' });
    } else {
      // Proceed with normal response handling
    }"

Scenario 2: Response exists but is an empty object #

Sometimes the server might return an empty JSON object ({}). To handle this, combine the check with Object.keys() to see if there are any properties in the response:

on="submit-success: 
    if(!event.response || Object.keys(event.response).length === 0) {
      AMP.setState({ errorMessage: 'Server returned an empty response.' });
    } else {
      // Handle non-empty response
      if(event.response.redirect) {
        AMP.navigateTo(url: event.response.redirect);
      }
    }"

Key Notes: #

• AMP's event handling supports basic JavaScript-like expressions, but avoid complex functions or loops—stick to simple conditionals and AMP-provided methods like AMP.setState or AMP.navigateTo.
• Always test your form with different server responses to ensure your fallback logic works as expected.

内容的提问来源于stack exchange，提问作者Maulik Patel