WriteConfig fails with JSON filetype when encountering arrays of objects and overwrites the config file with 0 bytes

[aeneasr]

Given the following JSON config file

foo:
  bar:
    - baz: 1
    - baz: 2

and the following go program

package main

import "github.com/ory/viper"

func main() {
	viper.SetConfigFile("./config.yaml")
	must(viper.ReadInConfig())
	viper.SetConfigFile("./config.json")
	must(viper.WriteConfig())
}

func must(err error) {
	if err != nil {
		panic(err)
	}
}

If executed, the program will fail with error

panic: While marshaling config: json: unsupported type: map[interface {}]interface {}

and even replace the config file's contents with an empty file. This works without issues when using YAML files.

Tested on latest master.

[aeneasr]

I've resolved this on our fork: https://github.com/ory/viper

[lukemarsden]

@spf13 hi, thank you for viper and cobra!

Any chance the fix for this in ory@5bace2a could be applied to spf13/viper please?

Basically, you can't json serialize viper configs that have been saved as yaml without this.

[sagikazarmark]

Should be a trivial fix once #1167 is merged.

[lukemarsden]

ok, looks like there's some other good-sounding fixes in ory@5bace2a as well, FWIW.

Thank you!

[sagikazarmark]

BTW using yaml v3 could also be solution for this problem. As of the next release you can do that by adding viper_yaml3 to your build tags. Let me know if that helps @lukemarsden