Assign data in onPreResponse lifecycle extension with takeover

[suhanw]

Support plan

• which support plan is this issue covered by? (e.g. Community, Core, Plus, or Enterprise): Community
• is this issue currently blocking your project? (yes/no): no
• is this issue affecting a production system? (yes/no): yes

Context

• node version: 12.14.0
• module version: yar@9.1.0, hapi@18.1.0
• environment (e.g. node, browser, native): node
• used with (e.g. hapi application, another framework, standalone, ...): hapi application
• any other relevant information: n/a

How can we help?

Hi! I'm fairly new to yar and hapi, but let me do my best to explain what I'm trying to accomplish:

• My Hapi server is making calls to another API service, and I use keepAlive agent on these calls, but the challenge we are facing now is every once in a while the service closes the connection and responds with ECONNRESET error.

• So our 'band-aid' solution for now is to detect these ECONNRESET errors, redirect to homepage, and show a simple alert.

• What I was hoping to do is to (a) detect the ECONNRESET response on the onPreResponse lifecycle, (b) set an alert message in session, and (c) change the response to a redirect to homepage. Here's the snippet:

  server.ext('onPreResponse', function (request, h){
  let response = request.response;
  
  if (response.message && typeof response.message.includes === 'function' && response.message.includes('ECONNRESET')) {
      request.yar.set('alerts', `Uh-oh. Something went wrong on our end. Please try again.`);
      return h.response().takeover().redirect('/');
  }
  
  // other code
  }

• Then, I was going to retrieve the alert message from session in one of my homepage route pre-handlers, and save the alert into an app state object that gets sent to the front-end to display the alert.

  
  server.route({
  method: 'GET',
  path: '/',
  config: {
      pre: [
          // other pre-handlers
          { method: getBase, assign: 'basePayload' },
          // other pre-handlers
      ],
      handler: Methods.render
  }
  });

const getBase = async (request, h) => { let alerts = request.yar.get('alerts');

// other code

}

But for some reason, the `alerts` in session did not persist from `onPreResponse` to the homepage pre-handler, i.e., `request.yar.get('alerts') === null` in the pre-handler. Is there something about `onPreResponse` lifecycle that doesn't allow me to save data into session? Any help is greatly appreciated. 

Below are my `yar` options. I tried to distill the code snippets to just the relevant parts, but let me know if I can provide any further info that might help. 
```js
{
    plugin: require('yar'),
    options: {
        name: nconf.get('redis:cookieName'),
        maxCookieSize: 0,
        cache: {
            expiresIn: nconf.get('redis:ttl')
        },
        cookieOptions: {
            ttl: nconf.get('redis:ttl'),
            password: nconf.get('redis:secret'),
            isSecure:
                process.env.NODE_ENV === 'production' ||
                process.env.NODE_ENV === 'staging' ||
                process.env.NODE_ENV === 'ephemeral',
            isHttpOnly:
                process.env.NODE_ENV === 'production' ||
                process.env.NODE_ENV === 'staging' ||
                process.env.NODE_ENV === 'ephemeral'
        },
        storeBlank: false
    }
},

Many thanks!

[hueniverse]

What is happening first, yar registration or your custom onPreResponse ext setup?

[suhanw]

They are both plugins included in the same array, but yar appears first in the array:

const plugins = [
    // other plugins
    {
        plugin: require('yar'),
        options: {
            name: nconf.get('redis:cookieName'),
            maxCookieSize: 0,
            cache: {
                expiresIn: nconf.get('redis:ttl')
            },
            cookieOptions: {
                ttl: nconf.get('redis:ttl'),
                password: nconf.get('redis:secret'),
                isSecure:
                    process.env.NODE_ENV === 'production' ||
                    process.env.NODE_ENV === 'staging' ||
                    process.env.NODE_ENV === 'ephemeral',
                isHttpOnly:
                    process.env.NODE_ENV === 'production' ||
                    process.env.NODE_ENV === 'staging' ||
                    process.env.NODE_ENV === 'ephemeral'
            },
            storeBlank: false
        }
    },
    // other plugins
    { plugin: require('./routes/main') },
    // other plugins
];

await server.register(plugins)

require('./routes/main') is the plugin where the onPreResponse ext setup lives.

[hueniverse]

You need to call the new await request.yar.commit(h) before returning the redirect.

[suhanw]

Is this a new feature that's not available in yar@9.1.0?

[hueniverse]

Only in 10.1.0.