ruby 41 lines · 6 steps

Previewing Rails mailers with sample data

An ActionMailer::Preview builds throwaway in-memory records so you can view every email variant in the browser.

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Rails Beginner mailer-previews test-fixtures in-memory-objects email
1class OrderMailerPreview < ActionMailer::Preview
2 def confirmation
3 OrderMailer.confirmation(sample_order)
4 end
5 
6 def shipped
7 order = sample_order
8 order.shipment = Shipment.new(
9 carrier: "UPS",
10 tracking_number: "1Z999AA10123456784",
11 estimated_delivery: 3.business_days.from_now
12 )
13 
14 OrderMailer.shipped(order)
15 end
16 
17 def refunded
18 OrderMailer.refunded(sample_order, amount: Money.new(2_499, "USD"))
19 end
20 
21 private
22 
23 def sample_order
24 Order.new(
25 id: 42,
26 number: "ORD-2024-000042",
27 placed_at: Time.current,
28 customer: Customer.new(name: "Ada Lovelace", email: "ada@example.com"),
29 line_items: [
30 LineItem.new(name: "Mechanical Keyboard", quantity: 1, unit_price: Money.new(12_900, "USD")),
31 LineItem.new(name: "USB-C Cable", quantity: 2, unit_price: Money.new(1_500, "USD"))
32 ],
33 shipping_address: Address.new(
34 line1: "1 Analytical Way",
35 city: "London",
36 postal_code: "EC1A 1BB",
37 country: "GB"
38 )
39 )
40 end
41end
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Mailer previews let you render real email templates in the browser without sending anything or hitting the database.
  2. 2Each public method maps to a preview URL, so one class documents every variant of a mailer.
  3. 3A private factory method keeps sample data in one place and lets each preview tweak just what it needs.

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