unpack

unpack

unpack provides a convenient mechanism to read a JSON config file comprising an single object with attributes representing unique values of the same structure:

{
	"countries": {
		"United Kingdom": { 
			"capital": "London",
			"population": {
				"2023": 66000000
			}
		},
		"United States": {
			"capital": "Washington",
			"population": {
				"2023": 314000000
			}
		}
	}
}

Use

Two struct types are required:

• A receiving struct that includes the attributes and associated json tags necessary to parse the data successfully - i.e. as required to use json.Unmarshal. In addition, this struct must have a pointer type implementation of SetName so that the struct implements the interface Unpackable.
• A factory struct that can manufacture pointer instances of the receiving struct

type Country struct {
	Name string
	Capital string `json:"capital"`
	Population map[string]int `json:"population"`
}

func (c *Country) SetName(name string) {
	c.Name = name
}

type CountryFact struct{}

func (f CountryFact) New() Unpackable {
	return new(Country)
}

func UnmarshalCountries(b []byte)  []*Country {
	items, _ := Unpack(b, CountryFact{})
	countries := make([]*Country, len(items))
	for i, item := range items {
		countries[i] = item.(*Country)
	}
	return countries
}

How?

The command line is all you need.

go get github.com/gford1000-go/unpack