Simple struct to map[string]interface{}

mapper.go

package search

import (
	"reflect"
	"strings"
)

// Build creates a map[string]interface object from a given
// struct based on tags.
func Build(tagName string, model interface{}) map[string]interface{} {
	out := map[string]interface{}{}

	t := reflect.TypeOf(model)
	v := reflect.ValueOf(model)

	for i := 0; i < t.NumField(); i++ {
		field := v.Field(i)
		tag := t.Field(i).Tag.Get(tagName)

		if strings.Contains(tag, ":") {
			tag = strings.Split(tag, ":")[1]
		}

		kind := field.Kind()
		var value reflect.Value

		if kind == reflect.Ptr {
			if !field.IsNil() {
				value = field.Elem()
				kind = field.Elem().Kind()
			} else {
				continue
			}
		} else {
			value = field
		}

		switch kind {
		case reflect.String:
			out[tag] = value.String()
		case reflect.Int:
			out[tag] = value.Int()
		case reflect.Float64:
			out[tag] = value.Float()
		case reflect.Bool:
			out[tag] = value.Bool()
		}
	}
	return out
}

mapper_test.go

package search

import (
	"math"
	"testing"
)

func TestBuild(t *testing.T) {
	type TestType struct {
		FirstName string  `test:"Firstname" json:"testing"` // make sure multiple tags don't break it.
		LastName  string  `test:"Lastname"`
		Age       int     `test:"Age"`
		Meh       *bool   `test:"Meh"`
		Meh2      *int    `test:"Meh2"`
		Pi        float64 `test:"Pi"`
	}

	meh := true

	i := TestType{
		FirstName: "xealgo",
		LastName:  "test",
		Age:       25,
		Meh:       &meh,
		Pi:        math.Pi,
	}

	// "Meh2" will not even get added to the return value from Build...
	o := Build("test", i)

	keys := map[string]interface{}{
		"Firstname": i.FirstName,
		"Lastname":  i.LastName,
		"Age":       int64(i.Age),
		"Meh":       meh,
		"Pi":        i.Pi,
	}

	for ik, iv := range keys {
		if ov, ok := o[ik]; ok {
			if ov != iv {
				t.Errorf("%s value %s expected %s", ik, ov, iv)
			}
		} else {
			t.Errorf("%s not found in output", ik)
		}
	}
}