Mutable package provides object changes tracking features and the way to set values to the struct dynamically by a destination field name (including nested structs).
This package needs Go version 1.9 or later

go get github.com/askretov/go-mutable

package main import "github.com/askretov/mutable" type NestedStruct struct {	mutable.Mutable FieldY string FieldZ []int64 } type MyStruct struct {	mutable.Mutable FieldA string FieldB int64 `mutable:"ignored"` FieldC NestedStruct `mutable:"deep"` } func main() { var m = &MyStruct{} // Mutable state init m.ResetMutableState(m) }

// Change values m.FieldA = "green" m.FieldC.FieldY = "stone" // Analyze changes fmt.Println(m.AnalyzeChanges())

Output:

{ "FieldA": { "old_value": "", "new_value": "green" }, "FieldC": { "nested_fields": { "FieldY": { "old_value": "", "new_value": "stone" } } } }

// Set values m.SetValue("FieldA", "white") m.SetValue("FieldC/FieldZ", "[1,2,3]") // You can set typed value or JSON string as well // Analyze changes fmt.Println(m.AnalyzeChanges())

Output:

{ "FieldA": { "old_value": "green", "new_value": "white" }, "FieldC": { "nested_fields": { "FieldZ": { "old_value": null, "new_value": [1, 2, 3] } } } }

Struct field's tag values should be set within mutable tag

• ignored - specifies ignoring of this field changes tracking
• deep - specifies the deep analyze of a field (only for struct kind fields). Instead of regular analysis of a field value itself, every field of nested struct will be analyzed for changes individually.

Example:

type MyStruct struct { mutable.Mutable FieldA string `mutable:"ignored"` FieldB AnotherStructType `mutable:"deep"` }

1. If you use a pointer to struct as field type and want to be able to use deep analysis, you have to embed Mutable for such nested field's struct as well.

   Example:

   type MyStruct struct { mutable.Mutable FieldA string FieldB *NestedStruct `mutable:"deep"` } type NestedStruct struct { mutable.Mutable // Mutable as well FieldY string FieldZ string }

2. If you pass a mutable object as an arg to a function, you have to pass it as a pointer to be able to use Mutable features.