Two things that have been of immense use are: -
Validating Data Structures And Variables In Golang
Regular Expressions 101
the latter of which has been very useful in terms of creating/testing/validating Regular Expressions ( aka RegExp ).
For me, the key thing is to be able to create validation rules within the JSON data structures, and then use the Go-Validator GoLang module/plugin/add-on: -
Specifically, I'm using the latest version 9 ( v9 ): -