# Hermes
[](https://travis-ci.org/matcornic/hermes)
[](https://goreportcard.com/report/github.com/matcornic/hermes)
[](https://codecov.io/github/matcornic/hermes/)
[](https://godoc.org/github.com/matcornic/hermes)
Hermes is the Go port of the great [mailgen](https://github.com/eladnava/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
```
Then, start using the package by importing and configuring it:
```go
// 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:
```go
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
* [Welcome](examples/welcome.go)
* [Receipt](examples/receipt.go)
* [Password Reset](examples/reset.go)
* [Maintenance](examples/maintenance.go)
To run the examples, go to `examples` folder, then run `go run *.go`. HTML and Plaintext example should be created in given theme folders.
## Plaintext E-mails
To generate a [plaintext version of the e-mail](https://litmus.com/blog/best-practices-for-plain-text-emails-a-look-at-why-theyre-important), simply call `GeneratePlainText` function:
```go
// 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:
* `default` by [Postmark Transactional Email Templates](https://github.com/wildbit/postmark-templates)
* `flat`, slightly modified from [Postmark Transactional Email Templates](https://github.com/wildbit/postmark-templates)
## RTL Support
To change the default text direction (left-to-right), simply override it as follows:
```go
// 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`:
```go
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`:
```go
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:
```go
// 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:
```go
// 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."
},
}
```
## 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:
```go
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",
},
},
},
},
}
```
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:
```go
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%",
},
CustomAlignement: map[string]string{
"Price": "right",
},
},
},
},
}
```
### Dictionary
To inject key-value pairs of data into the e-mail, supply the `Dictionary` object as follows:
```go
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:
```go
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, dictionnary 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](https://github.com/russross/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](CONTRIBUTING.md)
## License
Apache 2.0