Path.String() only returns a path in a Struct

[Josemaralves]

There is any reason why Path.String() only checks for a StructField while building the path?
This check is documented in the docs but it limits its utilization in maps of interface{} and can be improved with a little effort.

Right now it looks like this:

func (pa Path) String() string {
	var ss []string
	for _, s := range pa {
		if _, ok := s.(StructField); ok {
			ss = append(ss, s.String())
		}
	}
	return strings.TrimPrefix(strings.Join(ss, ""), ".")
}

the fix looks like:

func (pa Path) String() string {
	var ss []string
	for _, s := range pa {
		if _, ok := s.(StructField); ok {
			ss = append(ss, s.String())
		} else if index, ok := s.(MapIndex); ok {
			ss = append(ss, "."+index.Key().String())
		}
	}
	return strings.TrimPrefix(strings.Join(ss, ""), ".")
}

and a test case:

func Test(t *testing.T) {
	a := map[string]interface{}{
		"a": map[string]interface{}{
			"b": "bvalue",
			"c": "cvalue",
		},
		"d": "dvalue",
	}

	b := map[string]interface{}{
		"a": map[string]interface{}{
			"b": "evalue",
			"c": "cvalue",
		},
		"d": "dvalue",
	}

	diff := Diff(a, b, FilterPath(func(path Path) bool {
		return path.String() == "a.b"
	}, Ignore()))

	fmt.Println(diff)
}

[dsnet]

It was possibly a mistake to have Path.String only print the struct field accesses, but that behavior can't be changed since some tests already depend on that as a way to implement filters. For example, they'll do something like strings.Contains(p.String(), "Foo.Bar") to deliberately ignore any slice or map accesses between Foo and Bar.

If you want a complete print of the path, then use Path.GoString, which was added later.

[dsnet]

Closing as working as intended. The output of Path.String isn't going to change and Path.GoString has what is requested.