github.com/icza/dyno

dyno

Package dyno is a utility to work with dynamic objects at ease.

Primary goal is to easily handle dynamic objects and arrays (and a mixture of these) that are the result of unmarshaling a JSON or YAML text into an interface{} for example. When unmarshaling into interface{}, libraries usually choose either map[string]interface{} or map[interface{}]interface{} to represent objects, and []interface{} to represent arrays. Package dyno supports a mixture of these in any depth and combination.

When operating on a dynamic object, you designate a value you're interested in by specifying a path. A path is a navigation; it is a series of map keys and int slice indices that tells how to get to the value.

Should you need to marshal a dynamic object to JSON which contains maps with interface{} key type (which is not supported by encoding/json), you may use the ConvertMapI2MapS converter function.

The implementation does not use reflection at all, so performance is rather good.

Supported Operations

• Get a (typed) value denoted by a path: Get, GetInt, GetString, GetSlice, GetMapI, GetMapS

• Get a typed value with built-in conversion / parsing: GetInteger, GetFloating, GetBoolean

• Specialized get for maps with string keys: SGet

• Set a value denoted by a path: Set

• Specialized set for maps with string keys: SSet

• Append value(s) to a slice denoted by a path: Append, AppendMore

• Delete a key from a map or an element from a slice denoted by a path: Delete

• Convert maps with interface{} keys to maps with string keys: ConvertMapI2MapS

Example

Let's see a simple example editing a JSON text to mask out a password. This is a simplified version of the Example_jsonEdit example function:

src := `{"login":{"password":"secret","user":"bob"},"name":"cmpA"}`
var v interface{}
if err := json.Unmarshal([]byte(src), &v); err != nil {
	panic(err)
}
// Edit (mask out) password:
if err = dyno.Set(v, "xxx", "login", "password"); err != nil {
	fmt.Printf("Failed to set password: %v\n", err)
}
edited, err := json.Marshal(v)
fmt.Printf("Edited JSON: %s, error: %v\n", edited, err)

Output will be:

Edited JSON: {"login":{"password":"xxx","user":"bob"},"name":"cmpA"}, error: <nil>