Creating a Service
To build a service, start by creating a JavaScript file in your api/services/ folder. This file's job is to export a dictionary of functions, called helpers.
Make sure your service's filename ends in
Service.js. The first part of this filename (e.g.EmailService) will be used as the globally-accessible variable name for the service. We'll come back to that in a bit.
Services and their helper functions work best when you stick with strong conventions. In Sails apps, each helper exposed by a service expects either one or two arguments:
- The first argument (
options) is a dictionary of named customizations for our helper. In our example helpers above, we used options to pass in dynamic data likeemailAddressandname. - The second argument (
done) is a callback function, and it is only necessary if the helper is asynchronous. If a helper is asynchronous, then when it is called, a callback function must be passed in as the second argument. If truthy, the first argument of this callback (err) indicates that something went wrong (this is the asychronous equivalent of throwing an error). Otherwise, the first argument is set tonullorundefined. If there is a result (kind of the asynchronous equivalent of a return value), then it is passed through as the second argument.
For example, a service with a set of reusable email-related helpers might look something like this:
var Mailgun = require('machinepack-mailgun');
// api/services/EmailService.js
module.exports = {
/**
* Send a customized welcome email to the specified email address.
*
* @required {String} emailAddress
* The email address of the recipient.
* @required {String} firstName
* The first name of the recipient.
*/
sendWelcomeEmail: function (options, done) {
// Send an html email.
Mailgun.sendHtmlEmail({
apiKey: 'key-3432afa32e9401482aba183c13f3',
domain: 'sandbox5f89931913a9ab31130131350101.mailgun.og',
toEmail: options.emailAddress,
toName: options.firstName,
subject: 'Welcome, '+options.firstName+'!',
textMessage: options.firstName+',\nThanks for joining our community. If you have any questions, please don\'t hesitate to send them our way. Feel free to reply to this email directly.\n\nSincerely,\nThe Management',
htmlMessage: options.firstName+',<br><br><p>Thanks for joining our community. If you have any questions, please don\'t hesitate to send them our way. Feel free to reply to this email directly.</p><br/><span>Sincerely,</span><br/><strong>The Management</strong>',
fromEmail: '[email protected]',
fromName: 'Harold Greaseworthy',
}).exec(function (err) {
// If an unexpected error occurred...
if (err) { return done(err); }
// Otherwise, it worked!
return done();
});
},
/**
* Determine whether the specified email address is a valid internal email address (from within our company).
* Also, if "greaseworthy" was mispelled, correct the spelling. Harold REALLY hates when his name is mispelled.
* Finally, return the potentially-coerced email address.
*
* @required {String} emailAddress
* The email address to validate.
* @returns {String}
* The potentially coerced email address.
* @throws {Error} If this is not an internal email, or if Harold's last name is so badly misspelled
* that we couldn't fix it. (`code`==="notInternal").
*/
validateInternalEmailAddress: function (options){
var potentiallyFixedEmailAddress = options.emailAddress;
if (options.emailAddress.match(/@(greezeworthy|greeseworthy|greasworthy)\.enterprise$/i)) {
potentiallyFixedEmailAddress = options.emailAddress.replace(/@(.+)\.enterprise$/, '@greaseworthy.enterprise');
}
if (!potentiallyFixedEmailAddress.match(/@greaseworthy\.enterprise$/i)) {
var err = new Error('The specified email (`'+options.emailAddress+'`) is not a valid internal email address here at Greaseworthy enterprises. You probably misspelled Harold\'s last name. It is spelled "Greaseworthy".');
err.code = 'notInternal'
throw err;
}
return potentiallyFixedEmailAddress;
}
};
Using a Service
You can then call the helpers from this EmailService anywhere in your app, such as inside a controller action, or from within another service helper:
var potentiallyCorrectedEmail;
try {
potentiallyCorrectedEmail = EmailService.validateInternalEmailAddress({
emailAddress: req.param('email') // e.g. '[email protected]'
});
}
catch (err) {
if (err.code === 'notInternal') {
return res.badRequest('Failed to create account. The specified email address does not seem to be from Greaseworthy Enterprises.');
}
else { return res.serverError(err); }
}
User.create({
emailAddress: potentiallyCorrectedEmail,
firstName: req.param('firstName') // e.g. 'Mike'
}).exec(function (err) {
// If we made it here, we know we have a valid internal email address that satisfy all
// of Mr. Harold's most specific desires. So now we can send a welcome email.
EmailService.sendWelcomeEmail({
emailAddress: potentiallyCorrectedEmail,
firstName: req.param('firstName') // e.g. 'Mike'
}, function (err) {
if (err) { return res.serverError(err); }
// It worked! The welcome email was sent.
return res.ok();
});//</after EmailService.sendWelcomeEmail()>
});//</after User.create()>
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