How to unmarshal map[string]map[string]interface{}

[se7entyse7en]

Describe the bug
This is more a question. How can I properly unmarshal a toml as the following?

[tool.pydockenv]
name = "jupyter-notebook"
python = "3.7.4"

[tool.pydockenv.dependencies]
jupyter = "==1.0.0"

[tool.pydockenv.aliases]

[tool.pydockenv.aliases.notebook]
cmd = "jupyter notebook --allow-root --ip=0.0.0.0 --port=8888"
ports = [8888]

where there's no fixed structure for tool.pydockenv.aliases.

To Reproduce

type Config struct {
	Name          string
	Python        string
	ProjectDir    string
	Dependencies  map[string]string
	ContainerArgs map[string]string
	Aliases       map[string]map[string]interface{}
}

type RawConfig struct {
	Tool struct {
		Pydockenv *Config
	}
}

doc := []byte(`
[tool.pydockenv]
name = "jupyter-notebook"
python = "3.7.4"

[tool.pydockenv.dependencies]
jupyter = "==1.0.0"

[tool.pydockenv.aliases]

[tool.pydockenv.aliases.notebook]
cmd = "jupyter notebook --allow-root --ip=0.0.0.0 --port=8888"
ports = [8888]`)

rawConfig := environment.RawConfig{}
toml.Unmarshal(doc, &rawConfig)
fmt.Println("name=", rawConfig.Tool.Pydockenv.Name)
fmt.Println("aliases=", rawConfig.Tool.Pydockenv.Aliases)

This doesn't work as it raises:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x148e9b4]

at the line with where it should print the name.

If I change it to:

doc := []byte(`
[tool.pydockenv]
name = "jupyter-notebook"
python = "3.7.4"

[tool.pydockenv.dependencies]
jupyter = "==1.0.0"`)

then it assigns the name correctly, so I guess something is wrong in the Aliases field of Config. Here's the output:

name= jupyter-notebook
aliases= map[]

By using the original doc value, I also tried to change the Config as follows:

type Config struct {
	Name          string
	Python        string
	ProjectDir    string
	Dependencies  map[string]string
	ContainerArgs map[string]string
	Aliases       map[string]struct {
		Notebook struct {
			Cmd   string
			Ports []int
		}
	}
}

but the aliases is not there:

name= jupyter-notebook
aliases= map[]

Versions

• go-toml: v1.2.0
• go: go version go1.14
• operating system: macOS

[se7entyse7en]

To give more context the key of aliases can be any string, but the values are always cmd and ports, so for example:

[tool.pydockenv.aliases]

[tool.pydockenv.aliases.notebook1]
cmd = "jupyter notebook --allow-root --ip=0.0.0.0 --port=8888"
ports = [8888]`

[tool.pydockenv.aliases.notebook2]
cmd = "jupyter notebook --allow-root --ip=0.0.0.0 --port=8080"
ports = [8080]`

[se7entyse7en]

I also tried:

type Config struct {
	Name          string
	Python        string
	ProjectDir    string
	Dependencies  map[string]string
	ContainerArgs map[string]string
	Aliases       map[string]interface{}
}

type RawConfig struct {
	Tool struct {
		Pydockenv *Config
	}
}

doc := []byte(`
[tool.pydockenv]
name = "jupyter-notebook"
python = "3.7.4"

[tool.pydockenv.dependencies]
jupyter = "==1.0.0"

[tool.pydockenv.aliases]

[tool.pydockenv.aliases.notebook]
cmd = "jupyter notebook --allow-root --ip=0.0.0.0 --port=8888"
ports = [8888]`)

rawConfig := environment.RawConfig{}
toml.Unmarshal(doc, &rawConfig)
fmt.Println(rawConfig)

but it prints {{<nil>}}.

But maybe this is solved by #335 ?

[AllenX2018]

I look into the implementation of unmarshal and find that it seems go-toml do not support interface{} field unmarshalling for now. It need to be fixed. But for your case, I try:

	type Config struct {
		Name          string
		Python        string
		ProjectDir    string
		Dependencies  map[string]string
		ContainerArgs map[string]string
		Aliases       map[string]struct {
			Cmd   string
			Ports []int
		}
	}
	type RawConfig struct {
		Tool struct {
			Pydockenv *Config
		}
	}

	doc := []byte(`
[tool.pydockenv]
name = "jupyter-notebook"
python = "3.7.4"

[tool.pydockenv.dependencies]
jupyter = "==1.0.0"

[tool.pydockenv.aliases]

[tool.pydockenv.aliases.notebook]
cmd = "jupyter notebook --allow-root --ip=0.0.0.0 --port=8888"
ports = [8888]`)

	rawConfig := RawConfig{}
	if err := toml.Unmarshal(doc, &rawConfig); err != nil {
		fmt.Println(err)
	}

	fmt.Println("name=", rawConfig.Tool.Pydockenv.Name)
	fmt.Println("aliases=", rawConfig.Tool.Pydockenv.Aliases)

And it works in my environment(with latest version v1.6.0). Just change Aliases from map[string]map[string]interface{} to map[string]struct, but you don't need the Notebook part. Maybe you can try this as a workround.

[se7entyse7en]

Thanks a lot @AllenX2018! This is exactly what I was looking for!

[pelletier]

Awesome, glad you got unblocked! Thank you @AllenX2018. Unfortunately yes, the diagnostic is correct: support for map[.]interface{} has not been implemented yet. Issue #150 is the main one for that work.
Closing this issue, but feel free to re-open if you need anything else!