git.fractalqb.de/fractalqb/daq

daq – Data Queries

Access nested properties in Go data structures.

Go code for working with dynamic data structures can sometimes become somewhat verbose. E.g. like this:

var data any
json.Unmarshal([]byte(`{
	"glossary": {
		"title": "example glossary",
		"GlossDiv": {
			"title": "S",
			"GlossList": {
				"GlossEntry": {
					"ID": "SGML",
					"GlossTerm": "Standard Generalized Markup Language"
				}
			}
		}
	}
}`), &data)

title := "-no title-"
jObj, ok := data.(map[string]any)
if !ok {
	fmt.Println(title)
	return
}
if data = jObj["glossary"]; data == nil {
	fmt.Println(title)
	return
}
if jObj, ok = data.(map[string]any); !ok {
	fmt.Println(title)
	return
}
if data = jObj["title"]; data == nil {
	fmt.Println(title)
	return
}
title, _ = data.(string)

fmt.Println(title)
// Output:
// example glossary

Package daq helps for example to make it much more concise:

var data any
json.Unmarshal([]byte(`{
	"glossary": {
		"title": "example glossary",
		"GlossDiv": {
			"title": "S",
			"GlossList": {
				"GlossEntry": {
					"ID": "SGML",
					"GlossTerm": "Standard Generalized Markup Language"
				}
			}
		}
	}
}`), &data)

title := StringOr("-no title-")(Get(data, "glossary", "title"))

fmt.Println(title)
// Output:
// example glossary

In addition, daq can do even more, e.g. evaluate static data structures with the same API, iterate and … please consult the reference.