util.go

package mo

import (
	xerr "github.com/goclub/error"
	"go.mongodb.org/mongo-driver/bson"
	"reflect"
)
func ProjectByStructTag(v interface{}) bson.M {
	data := bson.M{}
	fields := scanProject(v)
	for _, field := range fields {
		data[field] = 1
	}
	return data
}
func autoScanProject(projection *interface{}, v interface{}) {
	if _, ok := v.(Document); ok == false {
		if *projection == nil {
			*projection = ProjectByStructTag(v)
		}
	}
}

func scanProject(v interface{}) (fields []string) {
	rValue := reflect.ValueOf(v)
	rValue = reflect.Indirect(rValue)
	rType := rValue.Type()
	tier := 0
	coreScanProject(rValue, rType, &fields, &tier)
	return
}
func coreScanProject(rValue reflect.Value, rType reflect.Type, fields *[]string, tier *int) {
	if *tier > 10 {
		panic(xerr.New("goclub/sql: Too many structures are nested"))
	}
	for i:=0;i<rType.NumField();i++ {
		structField := rType.Field(i)
		tag, has := structField.Tag.Lookup("bson")
		if !has {
			if structField.Type.Kind() == reflect.Struct {
				fieldValue := rValue.Field(i)
				coreScanProject(fieldValue, structField.Type, fields, tier)
				// fieldValue
			}
			continue
		}
		if tag != "" {
			*fields = append(*fields, tag)
		}
	}
}