hermes

package module
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 Go to latest Published: Sep 1, 2022 License: Apache-2.0 Imports: 7 Imported by: 0

README

Hermes

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Hermes is the Go port of the great mailgen engine for Node.js. Check their work, it's awesome! It's a package that generates clean, responsive HTML e-mails for sending transactional e-mails (welcome e-mails, reset password e-mails, receipt e-mails and so on), and associated plain text fallback.

Demo

Usage

First install the package:

go get -u github.com/matcornic/hermes/v2

Starting from release v2.0.0, Hermes uses Go modules. The latest version of Hermes requires at least Go 1.11 with gomodules enabled. You can still use an Hermes release compatible with prior Go versions by using v1.2.0 release

Then, start using the package by importing and configuring it:

// Configure hermes by setting a theme and your product info
h := hermes.Hermes{
    // Optional Theme
    // Theme: new(Default) 
    Product: hermes.Product{
        // Appears in header & footer of e-mails
        Name: "Hermes",
        Link: "https://example-hermes.com/",
        // Optional product logo
        Logo: "http://www.duchess-france.org/wp-content/uploads/2016/01/gopher.png",
    },
}

Next, generate an e-mail using the following code:

email := hermes.Email{
    Body: hermes.Body{
        Name: "Jon Snow",
        Intros: []string{
            "Welcome to Hermes! We're very excited to have you on board.",
        },
        Actions: []hermes.Action{
            {
                Instructions: "To get started with Hermes, please click here:",
                Button: hermes.Button{
                    Color: "#22BC66", // Optional action button color
                    Text:  "Confirm your account",
                    Link:  "https://hermes-example.com/confirm?token=d9729feb74992cc3482b350163a1a010",
                },
            },
        },
        Outros: []string{
            "Need help, or have questions? Just reply to this email, we'd love to help.",
        },
    },
}

// Generate an HTML email with the provided contents (for modern clients)
emailBody, err := h.GenerateHTML(email)
if err != nil {
    panic(err) // Tip: Handle error with something else than a panic ;)
}

// Generate the plaintext version of the e-mail (for clients that do not support xHTML)
emailText, err := h.GeneratePlainText(email)
if err != nil {
    panic(err) // Tip: Handle error with something else than a panic ;)
}

// Optionally, preview the generated HTML e-mail by writing it to a local file
err = ioutil.WriteFile("preview.html", []byte(emailBody), 0644)
if err != nil {
    panic(err) // Tip: Handle error with something else than a panic ;)
}

This code would output the following HTML template:

And the following plain text:


------------
Hi Jon Snow,
------------

Welcome to Hermes! We're very excited to have you on board.

To get started with Hermes, please click here: https://hermes-example.com/confirm?token=d9729feb74992cc3482b350163a1a010

Need help, or have questions? Just reply to this email, we'd love to help.

Yours truly,
Hermes - https://example-hermes.com/

Copyright © 2017 Hermes. All rights reserved.

Theme templates will be embedded in your application binary. If you want to use external templates (for configuration), use your own theme by implementing hermes.Theme interface with code searching for your files.

More Examples

To run the examples, go to examples folder, then run go run -a *.go. HTML and Plaintext example should be created in given theme folders.

Optionaly you can set the following variables to send automatically the emails to one your mailbox. Nice for testing template in real email clients.

  • HERMES_SEND_EMAILS=true
  • HERMES_SMTP_SERVER=<smtp_server> : for Gmail it's smtp.gmail.com
  • HERMES_SMTP_PORT=<smtp_port> : for Gmail it's 465
  • HERMES_SENDER_EMAIL=<your_sender_email>
  • HERMES_SENDER_IDENTITY=<the sender name>
  • HERMES_SMTP_USER=<smtp user> : usually the same than HERMES_SENDER_EMAIL
  • HERMES_TO=<recipients emails>: split by commas like myadress@test.com,somethingelse@gmail.com

The program will ask for your SMTP password. If needed, you can set it with HERMES_SMTP_PASSWORD variable (but be careful where you put this information !)

Plaintext E-mails

To generate a plaintext version of the e-mail, simply call GeneratePlainText function:

// Generate plaintext email using hermes
emailText, err := h.GeneratePlainText(email)
if err != nil {
    panic(err) // Tip: Handle error with something else than a panic ;)
}

Supported Themes

The following open-source themes are bundled with this package:

RTL Support

To change the default text direction (left-to-right), simply override it as follows:

// Configure hermes by setting a theme and your product info
h := hermes.Hermes {
    // Custom text direction
    TextDirection: hermes.TDRightToLeft,
}

Language Customizations

To customize the e-mail's greeting ("Hi") or signature ("Yours truly"), supply custom strings within the e-mail's Body:

email := hermes.Email{
    Body: hermes.Body{
        Greeting: "Dear",
        Signature: "Sincerely",
    },
}

To use a custom title string rather than a greeting/name introduction, provide it instead of Name:

email := hermes.Email{
    Body: hermes.Body{
        // Title will override `Name`
        Title: "Welcome to Hermes",
    },
}

To customize the Copyright, override it when initializing Hermes within your Product as follows:

// Configure hermes by setting a theme and your product info
h := hermes.Hermes{
    // Optional Theme
    // Theme: new(Default)
    Product: hermes.Product{
        // Appears in header & footer of e-mails
        Name: "Hermes",
        Link: "https://example-hermes.com/",
        // Custom copyright notice
        Copyright: "Copyright © 2017 Dharma Initiative. All rights reserved."
    },
}

To use a custom fallback text at the end of the email, change the TroubleText field of the hermes.Product struct. The default value is If you’re having trouble with the button '{ACTION}', copy and paste the URL below into your web browser.. The {ACTION} placeholder will be replaced with the corresponding text of the supplied action button:

// Configure hermes by setting a theme and your product info
h := hermes.Hermes{
    // Optional Theme
    // Theme: new(Default)
    Product: hermes.Product{
        // Custom trouble text
        TroubleText: "If the {ACTION}-button is not working for you, just copy and paste the URL below into your web browser."
    },
}

Since v2.1.0, Hermes is automatically inlining all CSS to improve compatibility with email clients, thanks to Premailer. You can disable this feature by setting DisableCSSInlining of Hermes struct to true.

h := hermes.Hermes{
    ...
    DisableCSSInlining: true,
}

Elements

Hermes supports injecting custom elements such as dictionaries, tables and action buttons into e-mails.

Action

To inject an action button in to the e-mail, supply the Actions object as follows:

email := hermes.Email{
    Body: hermes.Body{
        Actions: []hermes.Action{
            {
                Instructions: "To get started with Hermes, please click here:",
                Button: hermes.Button{
                    Color: "#22BC66", // Optional action button color
                    Text:  "Confirm your account",
                    Link:  "https://hermes-example.com/confirm?token=d9729feb74992cc3482b350163a1a010",
                },
            },
        },
    },
}

Alternatively, instead of having a button, an action can be an invite code as follows:

email := hermes.Email{
    Body: hermes.Body{
        Actions: []hermes.Action{
            {
                Instructions: "To get started with Hermes, please use the invite code:",
                InviteCode: "123456",
            },
        },
    },
}

To inject multiple action buttons in to the e-mail, supply another struct in Actions slice Action.

Table

To inject a table into the e-mail, supply the Table object as follows:

email := hermes.Email{
    Body: hermes.Body{
        Table: hermes.Table{
            Data: [][]hermes.Entry{
                // List of rows
                {   
                    // Key is the column name, Value is the cell value
                    // First object defines what columns will be displayed
                    {Key: "Item", Value: "Golang"},
                    {Key: "Description", Value: "Open source programming language that makes it easy to build simple, reliable, and efficient software"},
                    {Key: "Price", Value: "$10.99"},
                },
                {
                    {Key: "Item", Value: "Hermes"},
                    {Key: "Description", Value: "Programmatically create beautiful e-mails using Golang."},
                    {Key: "Price", Value: "$1.99"},
                },
            },
            Columns: hermes.Columns{
                // Custom style for each rows
                CustomWidth: map[string]string{
                    "Item":  "20%",
                    "Price": "15%",
                },
                CustomAlignment: map[string]string{
                    "Price": "right",
                },
            },
        },
    },
}
Dictionary

To inject key-value pairs of data into the e-mail, supply the Dictionary object as follows:

email := hermes.Email{
    Body: hermes.Body{
        Dictionary: []hermes.Entry{
            {Key: "Date", Value: "20 November 1887"},
            {Key: "Address", Value: "221B Baker Street, London"},
        },
    },
}
Free Markdown

If you need more flexibility in the content of your generated e-mail, while keeping the same format than any other e-mail, use Markdown content. Supply the FreeMarkdown object as follows:

email := hermes.Email{
		Body: hermes.Body{
			FreeMarkdown: `
> _Hermes_ service will shutdown the **1st August 2017** for maintenance operations. 

Services will be unavailable based on the following schedule:

| Services | Downtime |
| :------:| :-----------: |
| Service A | 2AM to 3AM |
| Service B | 4AM to 5AM |
| Service C | 5AM to 6AM |

---

Feel free to contact us for any question regarding this matter at [support@hermes-example.com](mailto:support@hermes-example.com) or in our [Gitter](https://gitter.im/)

`,
		},
	}
}

This code would output the following HTML template:

And the following plaintext:

------------
Hi Jon Snow,
------------

> 
> 
> 
> Hermes service will shutdown the *1st August 2017* for maintenance
> operations.
> 
> 

Services will be unavailable based on the following schedule:

+-----------+------------+
| SERVICES  |  DOWNTIME  |
+-----------+------------+
| Service A | 2AM to 3AM |
| Service B | 4AM to 5AM |
| Service C | 5AM to 6AM |
+-----------+------------+

Feel free to contact us for any question regarding this matter at support@hermes-example.com ( support@hermes-example.com ) or in our Gitter ( https://gitter.im/ )

Yours truly,
Hermes - https://example-hermes.com/

Copyright © 2017 Hermes. All rights reserved.

Be aware that this content will replace existing tables, dictionary and actions. Only intros, outros, header and footer will be kept.

This is helpful when your application needs sending e-mails, wrote on-the-fly by adminstrators.

Markdown is rendered with Blackfriday, so every thing Blackfriday can do, Hermes can do it as well.

Troubleshooting

  1. After sending multiple e-mails to the same Gmail / Inbox address, they become grouped and truncated since they contain similar text, breaking the responsive e-mail layout.

Simply sending the X-Entity-Ref-ID header with your e-mails will prevent grouping / truncation.

Contributing

See CONTRIBUTING.md

License

Apache 2.0

FOSSA Status

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type Action 

type Action struct {
	Instructions string
	Button       Button
	InviteCode   string
}

Action is anything the user can act on (i.e., click on a button, view an invite code)

type Body 

type Body struct {
	Name         string   // The name of the contacted person
	Intros       []string // Intro sentences, first displayed in the email
	Dictionary   []Entry  // A list of key+value (useful for displaying parameters/settings/personal info)
	Tables       []Table  // Tables is a list of tables where you can put data (pricing grid, a bill, and so on)
	Actions      []Action // Actions are a list of actions that the user will be able to execute via a button click
	Outros       []string // Outro sentences, last displayed in the email
	Greeting     string   // Greeting for the contacted person (default to 'Hi')
	Signature    string   // Signature for the contacted person (default to 'Yours truly')
	Title        string   // Title replaces the greeting+name when set
	FreeMarkdown Markdown // Free markdown content that replaces all content other than header and footer
}

Body is the body of the email, containing all interesting data

type Button 

type Button struct {
	Color     string
	TextColor string
	Text      string
	Link      string
}

Button defines an action to launch

type Columns 

type Columns struct {
	CustomWidth     map[string]string
	CustomAlignment map[string]string
}

Columns contains meta-data for the different columns

type Default 

type Default struct{}

Default is the theme by default

func (*Default) HTMLTemplate 

func (dt *Default) HTMLTemplate() string

HTMLTemplate returns a Golang template that will generate an HTML email.

func (*Default) Name 

func (dt *Default) Name() string

Name returns the name of the default theme

func (*Default) PlainTextTemplate 

func (dt *Default) PlainTextTemplate() string

PlainTextTemplate returns a Golang template that will generate an plain text email.

type Email 

type Email struct {
	Body Body
}

Email is the email containing a body

type Entry 

type Entry struct {
	Key   string
	Value string
}

Entry is a simple entry of a map Allows using a slice of entries instead of a map Because Golang maps are not ordered

type Flat 

type Flat struct{}

Flat is a theme

func (*Flat) HTMLTemplate 

func (dt *Flat) HTMLTemplate() string

HTMLTemplate returns a Golang template that will generate an HTML email.

func (*Flat) Name 

func (dt *Flat) Name() string

Name returns the name of the flat theme

func (*Flat) PlainTextTemplate 

func (dt *Flat) PlainTextTemplate() string

PlainTextTemplate returns a Golang template that will generate an plain text email.

type Hermes 

type Hermes struct {
	Theme              Theme
	TextDirection      TextDirection
	Product            Product
	DisableCSSInlining bool
}

Hermes is an instance of the hermes email generator

func (*Hermes) GenerateHTML 

func (h *Hermes) GenerateHTML(email Email) (string, error)

GenerateHTML generates the email body from data to an HTML Reader This is for modern email clients

func (*Hermes) GeneratePlainText 

func (h *Hermes) GeneratePlainText(email Email) (string, error)

GeneratePlainText generates the email body from data This is for old email clients

type Markdown 

type Markdown template.HTML

Markdown is a HTML template (a string) representing Markdown content https://en.wikipedia.org/wiki/Markdown

func (Markdown) ToHTML 

func (c Markdown) ToHTML() template.HTML

ToHTML converts Markdown to HTML

type Product 

type Product struct {
	Name        string
	Link        string // e.g. https://matcornic.github.io
	Copyright   string // Copyright © 2019 Hermes. All rights reserved.
	TroubleText string // TroubleText is the sentence at the end of the email for users having trouble with the button (default to `If you’re having trouble with the button '{ACTION}', copy and paste the URL below into your web browser.`)
}

Product represents your company product (brand) Appears in header & footer of e-mails

type Table 

type Table struct {
	Title   string    //Table title
	Data    [][]Entry // Contains data
	Columns Columns   // Contains meta-data for display purpose (width, alignement)
}

Table is an table where you can put data (pricing grid, a bill, and so on)

type Template 

type Template struct {
	Hermes Hermes
	Email  Email
}

Template is the struct given to Golang templating Root object in a template is this struct

type TextDirection 

type TextDirection string

TextDirection of the text in HTML email 

const TDLeftToRight TextDirection = "ltr"

TDLeftToRight is the text direction from left to right (default) 

const TDRightToLeft TextDirection = "rtl"

TDRightToLeft is the text direction from right to left

type Theme 

type Theme interface {
	Name() string              // The name of the theme
	HTMLTemplate() string      // The golang template for HTML emails
	PlainTextTemplate() string // The golang templte for plain text emails (can be basic HTML)
}

Theme is an interface to implement when creating a new theme

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