go-bo4e

README

go-bo4e

Business Objects for Energy (BO4E) Implementation in Go. Highlights are

• includes json tags for easy (un)marshalling
• comes with builtin validator logic
• is linted and has decent test coverage

This package (as of November 2021) implements

• BO Ansprechpartner
• BO Bilanzierung (not official BO4E Standard yet)
• BO Energiemenge
• BO Geschaeftspartner
• BO Handelsunstimmigkeit (not official BO4E Standard yet)
• BO Lastgang
• BO Marktlokation
• BO Marktteilnehmer
• BO Messlokation
• BO Preisblatt
• BO Rechnung
• BO Reklamation (not official BO4E Standard yet)
• BO Vertrag
• BO Zaehler

so far.

Installation

go get github.com/hochfrequenz/go-bo4e

Minimal Working Example

package main

import (
	"encoding/json"
	"fmt"
	"github.com/go-playground/validator/v10"
	"github.com/hochfrequenz/go-bo4e/bo"
	"github.com/hochfrequenz/go-bo4e/com"
	"github.com/hochfrequenz/go-bo4e/enum/botyp"
	"github.com/hochfrequenz/go-bo4e/enum/landescode"
	"github.com/hochfrequenz/go-bo4e/enum/sparte"
)

func main() {
	melo := bo.Messlokation{
		Geschaeftsobjekt: bo.Geschaeftsobjekt{
			BoTyp:             botyp.MESSLOKATION,
			VersionStruktur:   "1",
			ExterneReferenzen: nil,
		},
		MesslokationsId: "DE0000011111222223333344444555556",
		Sparte:          sparte.STROM,
		Messadresse: &com.Adresse{
			Postleitzahl: "82031",
			Ort:          "Grünwald",
			Strasse:      "Nördliche Münchner Straße",
			Hausnummer:   "27A",
			Landescode:   landescode.DE,
		},
	}
	vali := validator.New()
	err := vali.Struct(melo)
	if err == nil {
		fmt.Println("The MeLo is valid.")
	}
	meloBytes, err := json.Marshal(melo)
	meloJson := string(meloBytes)
	fmt.Print(meloJson)
}

Use this in the Go Playground.

Caveats

When serializing decimals (e.g. Zaehlwerk.Wandlerfaktor) you'll notice that the decimals are by default serialized as strings

{
  "wandlerfaktor": "0.8"
}

instead of a number like

{
  "wandlerfaktor": 0.8
}

This is the default behaviour defined in the decimal package . You can change the behaviour by setting

decimal.MarshalJSONWithoutQuotes = true

as described f.e. in issue 21 there.

Version Notes

Handling Unknown Fields in (Un)Marshaling since v0.0.36

If you're unmarshaling a Business Object that contains fields which are not defined in the BO structs, they'll be deserialized into the Geschaeftsobjekt.ExtensionData map. This behaviour is achieved by implementing a custom UnmarshalJSON func. The ExtensionData, if not empty, will also be marshalled on root level by default.

⚠ This feature is experimental and for now only works for the Marktlokation.

General Default Value Marshalling Behaviour since v0.0.22

Since v0.0.22 default values are no longer marshalled/included in serialized Business Objects or COMponents. Prior to v0.0.22 default values of required fields serialized as f.e. empty string, null or empty slice. For enums this behaviour had already been introduced in v0.0.19 (see below). This is a step towards decoupling of serialization and validation.

Default Enum Marshalling Behaviour since v0.0.19

Since version v0.0.19 default enum values are no longer serialized/marshalled. Prior to v0.0.19 fields with an enum type that are required but were uninitialized had been serialized as NameOfEnum(0). This change is a step towards decoupling of serialization and validation.

Breaking Changes introduced in v0.0.13 and v0.0.14:

• The struct that is embedded in all BusinessObjects is now called Geschaeftsobjekt (was BusinessObject <=v0.0.12)to be consistent with the official documentation
• BusinessObject is now the name of the interface that all structs with embedded Geschaeftsobjekt implement
• Enums are consistently written in upper case (PR 32)

Other Noteworthy BO4E Implementations

• C# / .NET
• Python
• Kotlin
• TypeScript

Contributing

Contributions are welcome. Feel free to open a Pull Request against the main branch of this repository. Please provide unit tests if you contribute logic beyond bare bare business object definitions. We do track our modification proposals to the official BO4E standard in a separate repository: BO4E-modification-proposals.

Adding Enums

When adding Enums there are two packages (stringer , jsonenums) needed to go-generate additional files, which contain an implementation of the fmt.Stringer and json.Marshaler interface for the respective enum. Since they are just needed for the code generation, but not a real dependency we don't want them in the go.mod file. One way to install them is outside of your directory with:

go install github.com/campoy/jsonenums@latest
go install golang.org/x/tools/cmd/stringer@latest

Hochfrequenz

Hochfrequenz Unternehmensberatung GmbH is a Grünwald (near Munich) based consulting company with offices in Berlin and Bremen. We're not only the main contributor to open source BO4E software but, according to Kununu ratings, also among the most attractive employers within the German energy market. Applications of talented developers are welcome at any time! Please consider visiting our career page ( German only).