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Schema tutorialLesson 14: Sending emails with pleasure

Lesson 14: Sending emails with pleasure

This tutorial lesson demonstrates several capabilities by Gato GraphQL to send emails.

Sending emails

We send emails via mutation _sendEmail provided by the Email Sender extension.

  • The email is sent with content type "text" or "HTML" depending on what property from the messageAs input is used
  • The from input is optional; if not provided, the settings stored in WordPress are used
  • _sendEmail executes WordPress wp_mail function, so it will use the configuration defined for sending emails in WordPress (such as the SMTP provider to use)
mutation {
  sendTextEmail: _sendEmail(
    input: {
      from: {
        email: "from@email.com"
        name: "Me myself"
      }
      replyTo: "replyTo@email.com"
 
      to: "target@email.com"
      cc: ["cc1@email.com", "cc2@email.com"]
      bcc: ["bcc1@email.com", "bcc2@email.com", "bcc3@email.com"]
      
      subject: "Email with text content"
      messageAs: {
        text: "Hello world!"
      }
    }
  ) {
    status
    errors {
      __typename
      ...on ErrorPayload {
        message
      }
    }
  }
  
  sendHTMLEmail: _sendEmail(
    input: {
      to: "target@email.com"
      subject: "Email with HTML content"
      messageAs: {
        html: "<p>Hello world!</p>"
      }
    }
  ) {
    status
    errors {
      __typename
      ...on ErrorPayload {
        message
      }
    }
  }
}

Composing the email using Markdown

Field _strConvertMarkdownToHTML from the Helper Function Collection extension converts Markdown to HTML.

We can use this field to compose the email using Markdown:

query GetEmailData {
  emailMessage: _strConvertMarkdownToHTML(
    text: """
 
We have great news: **Version 1.0 of our plugin will be released soon!**
 
If you'd like to help us beta test it, please complete [this form](https://forms.gle/FpXNromWAsZYC1zB8).
 
_Please reply by 30th June 🙏_
 
Thanks!
 
    """
  )
    @export(as: "emailMessage")
}
 
mutation SendEmail @depends(on: "GetEmailData") {
  _sendEmail(
    input: {
      to: "target@email.com"
      subject: "Great news!"
      messageAs: {
        html: $emailMessage
      }
    }
  ) {
    status
    errors {
      __typename
      ...on ErrorPayload {
        message
      }
    }
  }
}

Injecting dynamic data into the email

Using the function fields provided by the PHP Functions via Schema, we can create a message template containing placeholders, and replace them with dynamic data:

query GetPostData($postID: ID!) {
  post(by: {id: $postID}) {
    title @export(as: "postTitle")
    excerpt @export(as: "postExcerpt")
    url @export(as: "postLink")
    author {
      name @export(as: "postAuthorName")
      url @export(as: "postAuthorLink")
    }
  }
}
 
query GetEmailData @depends(on: "GetPostData") {
  emailMessageTemplate: _strConvertMarkdownToHTML(
    text: """
 
There is a new post by [{$postAuthorName}]({$postAuthorLink}):
 
**{$postTitle}**: {$postExcerpt}
 
[Read online]({$postLink})
 
    """
  )
  emailMessage: _strReplaceMultiple(
    search: ["{$postAuthorName}", "{$postAuthorLink}", "{$postTitle}", "{$postExcerpt}", "{$postLink}"],
    replaceWith: [$postAuthorName, $postAuthorLink, $postTitle, $postExcerpt, $postLink],
    in: $__emailMessageTemplate
  )
    @export(as: "emailMessage")
  subject: _sprintf(string: "New post created by %s", values: [$postAuthorName])
    @export(as: "emailSubject")
}
 
mutation SendEmail @depends(on: "GetEmailData") {
  _sendEmail(
    input: {
      to: "target@email.com"
      subject: $emailSubject
      messageAs: {
        html: $emailMessage
      }
    }
  ) {
    status
  }
}

Sending a notification email to the admin

We can retrieve the email of the admin user from the WordPress wp_options table, and inject this value into the to field:

query ExportData {
  adminEmail: optionValue(name: "admin_email")
    @export(as: "adminEmail")
}
 
mutation SendEmail @depends(on: "ExportData") {
  _sendEmail(
    input: {
      to: $adminEmail
      subject: "Admin notification"
      messageAs: {
        html: "There is a new post on the site, go check!"
      }
    }
  ) {
    status
  }
}

Alternatively, if Nested Mutations is enabled in the Schema Configuration, we can retrieve the admin email in the mutation operation already (and inject it into the mutation via Field to Input):

mutation SendEmail {
  adminEmail: optionValue(name: "admin_email")
  _sendEmail(
    input: {
      to: $__adminEmail
      subject: "Admin notification"
      messageAs: {
        html: "There is a new post on the site, go check!"
      }
    }
  ) {
    status
  }
}

Sending a personalized email to users

For this GraphQL query to work, the Schema Configuration applied to the endpoint needs to have Nested Mutations enabled

Because _sendEmail is a global field (or, more precisely, a global mutation), it can be executed on any type from the GraphQL schema, including User.

This query retrieves a list of users, obtains their data (name, email and number of remaining credits, which is stored as meta), and sends a personalized email to each of them:

mutation {
  users {
    email
    displayName
    credits: metaValue(key: "credits")
    
    # If the user does not have meta entry "credits", use `0` credits
    hasNoCreditsEntry: _isNull(value: $__credits)
    remainingCredits: _if(condition: $__hasNoCreditsEntry, then: 0, else: $__credits)
 
    emailMessageTemplate: _strConvertMarkdownToHTML(
      text: """
 
Hello %s,
 
Your have **%s remaining credits** in your account.
 
Would you like to [buy more](%s)?
 
      """
    )
    emailMessage: _sprintf(
      string: $__emailMessageTemplate,
      values: [
        $__displayName,
        $__remainingCredits,
        "https://mysite.com/buy-credits"
      ]
    )
 
    _sendEmail(
      input: {
        to: $__email
        subject: "Remaining credits alert"
        messageAs: {
          html: $__emailMessage
        }
      }
    ) {
      status
      errors {
        __typename
        ...on ErrorPayload {
          message
        }
      }
    }
  }
}