How to generate json model file for new doctype in new app？

Frappe Framework Customization
1

I followed the tutorial:
https://frappe.io/docs/user/en/tutorial/models
the tutorial says"When you update the DocType, the JSON model file is updated and whenever bench migrate is executed"
but json files dosen’t appear,how can i generate it？

2

The developer mode has to be set to 1 for this to happen. A quick search of “Set Developer Mode” in this forum will return a lot of posts to help you.

3

thank you！