Heroku Review App Cannot find Database - heroku

Question

I have a Django app, which uses a postgres database hosted on heroku. I'm trying to create a review app based on this Django app. However, I can't seem to access my DB on the review app. I've added a postdeploy script as shown in the app.json below but it doesn't seem to solve it:
{
"name": "bookapp",
"scripts": {
"postdeploy": "pg_dump $DATABASE_URL | psql $DATABASE_URL && python
./manage.py migrate"
},
"env": {
"DATABASE_URL": {
"required": true
},
"QV_CLOUDINARY_API_KEY": {
"required": true
},
"QV_CLOUDINARY_API_SECRET": {
"required": true
},
"QV_CLOUDINARY_CLOUD_NAME": {
"required": true
},
"QV_DATABASE_NAME": {
"required": true
},
"QV_DATABASE_PASSWORD": {
"required": true
},
"QV_DATABASE_USER": {
"required": true
},
"QV_SECRET_KEY": {
"required": true
}
},
"formation": {
"web": {
"quantity": 1
}
},
"addons": [
"heroku-postgresql"
],
"buildpacks": [
{
"url": "heroku/python"
}
]
}

Answer 1

Found the solution!.
The app.json file above is correct. Apparently the post-deploy script only runs the first time the app is created. I had to close the Pull Request for the review app and re-open a new one so that a new review app is created. Doing that executed the post-deploy script and i was able to access my DB.