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How I made a simplest and useful library in Golang by learning Reflection’s workby@imantumorang
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How I made a simplest and useful library in Golang by learning Reflection’s work

by Iman TumorangSeptember 7th, 2017
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A few a months ago, I was creating a simple library in golang, to help golang engineers when testing their function. It just a simple library that will generate fake and random data based on their struct. The idea comes when I was creating unit testing in every function I have, and making different struct , it’s a wasting time.

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Learn by doing: a reflection in Golang

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A few a months ago, I was creating a simple library in golang, to help golang engineers when testing their function. It just a simple library that will generate fake and random data based on their struct. The idea comes when I was creating unit testing in every function I have, and making different struct , it’s a wasting time.

The libary can seen here


bxcodec/faker_faker - Go (Golang) Fake Data Generator for Struct_github.com

How to use it :

$ go get github.com/bxcodec/faker

Then import into your test file.

This simple library I made with utilizing the reflection feature in golang. The work is simple , you only define you struct and my library will generate you a dummy data based on your struct.

Example :

When you run that your object will filled with random data :




$ go run main.go$ {Int:37 String:LOftACEPfclEWQDBqAaaqyVis Bool:false SString:[yWgdkZQtbTmi] Struct:{Number:36 Height:0.021622694665801242AnotherStruct:{Image:wUvHuSlyJYknWbqUbWtYGrMrZ}}}

Even you have a nested struct, as long as they do not pointer struct , they will safe to generated.

Good, How did you do that?

Reflection

In golang, there is a built in package that we can use for reflection data type it’s called reflect . You can see what reflect can do in the official documentations https://golang.org/pkg/reflect/

Basically , I just get the data type, then random data based on it’s type.

var a int64



ref :=reflect.ValueOf(&a) //will return reflect.Value objects ;//Pass with refferences for data//manipulation


ref=reflect.Indirect(ref) //accessing the value only that pointed by//ref

kind:= ref.Kind() // will return the kind of the reflected value

if kind == reflect.Int64{


val:= int64(100) //Data will assigned. For fake data, this//should randomized


ref.Set(reflect.ValueOf(val)) //Set the value}

fmt.Println("Value of a ", a) //Will print 100

Live example you could run here


The Go Playground_The playground service is used by more than just the official Go project ( Go by Example is one other instance) and we…_play.golang.org

Just as simple as it. Now I can generate a dummy data for my struct and help me when doing automation testing with random data.

But, this library still need more improvements, because it’s still can’t randomize data for array of struct. I’ve tried many ways, but still not good, maybe it’s impossible to do, or maybe I still need to learn more.

Happy coding…. :)

If you have a question , or need more explanation, or something, that I can not explain well here, you can ask me from my linkedin or email me. Thank you


Trying Clean Architecture on Golang_Independent, Testable , and Clean_hackernoon.com


Implementing gRPC service in Golang_Guide to make gRPC service using clean architecture in golang._toolbox.kurio.co.id


I’m Learning to Use Flatbuffer in Go (Golang) , Here What I Learn_Flatbuffer for serializing data._toolbox.kurio.co.id