在Golang中将结构转换为地图的函数

Question

I want to convert a struct to map in Golang. It would also be nice if I could use the JSON tags as keys in the created map (otherwise defaulting to field name).

Edit TL;DR version, Jun 15, 2015

If you want the fast solution for converting a structure to map, see the accepted answer, upvote it and use that package.

Happy coding! :)

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Original Post

So far I have this function, I am using the reflect package but I don't understand well how to use the package, please bear with me.

func ConvertToMap(model interface{}) bson.M {
    ret := bson.M{}

    modelReflect := reflect.ValueOf(model)

    if modelReflect.Kind() == reflect.Ptr {
        modelReflect = modelReflect.Elem()
    }

    modelRefType := modelReflect.Type()
    fieldsCount := modelReflect.NumField()

    var fieldData interface{}

    for i := 0; i < fieldsCount; i++ {
        field := modelReflect.Field(i)

        switch field.Kind() {
        case reflect.Struct:
            fallthrough
        case reflect.Ptr:
            fieldData = ConvertToMap(field.Interface())
        default:
            fieldData = field.Interface()
        }

        ret[modelRefType.Field(i).Name] = fieldData
    }

    return ret
}

Also I looked at JSON package source code, because it should contain my needed implementation (or parts of it) but don't understand too much.

Answer 1

I also had need for something like this. I was using an internal package which was converting a struct to a map. I decided to open source it with other struct based high level functions. Have a look:

https://github.com/fatih/structs

It has support for:

• Convert struct to a map
• Extract the fields of a struct to a []string
• Extract the values of a struct to a []values
• Check if a struct is initialized or not
• Check if a passed interface is a struct or a pointer to struct

You can see some examples here: http://godoc.org/github.com/fatih/structs#pkg-examples For example converting a struct to a map is a simple:

type Server struct {
    Name    string
    ID      int32
    Enabled bool
}

s := &Server{
    Name:    "gopher",
    ID:      123456,
    Enabled: true,
}

// => {"Name":"gopher", "ID":123456, "Enabled":true}
m := structs.Map(s)

The structs package has support for anonymous (embedded) fields and nested structs. The package provides to filter certain fields via field tags.