Open Source Ecosystems

structwalk

Battle-tested Go struct and map traversal utilities. Has been around since 2016.

FieldValue

Returns a value of a field in deeply nested structs, will traverse both maps and structs.

structwalk.FieldValue(path string, in interface{}) (v interface{}, found bool)

Example:

var object = struct {
    Foo struct {
        Bar struct {
            Baz map[string]int
        }
    }
}{}
object.Foo.Bar.Baz = map[string]int{
    "Kek": 5,
}

value, found := structwalk.FieldValue("Foo.Bar.Baz.Kek", object)
// value = 5
// found = true

GetterValue

A special case of FieldValue, that checks if for a field named Foo, there is a method that is named FooBytes(). Useful to avoid allocations when accesing string values that can be returned as a memory pointer instead (e.g. in capnproto).

structwalk.GetterValue(path string, in interface{}) (v interface{}, found bool)

FieldList

Simply print the list of fields of a struct, recursively.

structwalk.FieldList(in interface{}) []string

Example:

var object = struct {
    Foo struct {
        Bar struct {
            Baz  map[string]int
            Baz2 string
        }
    }
}{}
object.Foo.Bar.Baz = map[string]int{
    "Kek": 5,
    "Lol": 4,
}

list := structwalk.FieldList(object)
// [
//  "Foo.Bar.Baz.Kek",
//  "Foo.Bar.Baz.Lol",
//  "Foo.Bar.Baz2"
// ]

GetterList

Returns list of getter methods that accept no arguments (except the implicit pointer to the struct) and return one value. Can be used in templates to get a value that is not accessible by a method.

structwalk.GetterList(in interface{}) []string

Example:

type SomeDecorated struct{}

func (s SomeDecorated) Foo() string {
    return "foo"
}

func (s SomeDecorated) FooBytes() []byte {
    return []byte("foo")
}

func (s SomeDecorated) Bar() SomeStruct {
    return SomeStruct{}
}

list := structwalk.FieldList(SomeDecorated{})
// [
//   "Bar.Baz",
//   "Foo",
//   "FooBytes"
// ]