From 35d0a7f1a7fdd74988495061919e60ac609e3e1d Mon Sep 17 00:00:00 2001
From: Muhsin Keloth <muhsinkeramam@gmail.com>
Date: Thu, 21 Aug 2025 16:44:51 +0530
Subject: [PATCH] feat: Add liquid template support for WhatsApp template
 parameters (#12227)

Extends liquid template processing to WhatsApp `template_params`,
allowing dynamic variable substitution in template parameter values.

Users can now use liquid variables in WhatsApp template parameters:

```
{
  "template_params": {
    "name": "greet",
    "category": "MARKETING",
    "language": "en",
    "processed_params": {
      "body": {
        "customer_name": "{{contact.name}}",
        "customer_email": "{{contact.email | default: 'no-email@example.com'}}"
      }
    }
  }
}

```

When the message is saved, {{contact.name}} gets replaced with the
actual contact name.

Supported Variables

- {{contact.name}}, {{contact.email}}, {{contact.phone_number}}
- {{agent.name}}, {{agent.first_name}}
- {{account.name}}, {{inbox.name}}
- {{conversation.display_id}}
- Custom attributes: {{contact.custom_attribute.key_name}}
- Liquid filters: {{ contact.email | default: "fallback@example.com" }}
---
 app/models/concerns/liquidable.rb         |  58 ++++++++
 spec/models/concerns/liquidable_shared.rb | 155 ++++++++++++++++++++++
 2 files changed, 213 insertions(+)

diff --git a/app/models/concerns/liquidable.rb b/app/models/concerns/liquidable.rb
index 8a30977a7..8a90f5f9f 100644
--- a/app/models/concerns/liquidable.rb
+++ b/app/models/concerns/liquidable.rb
@@ -3,6 +3,7 @@ module Liquidable
 
   included do
     before_create :process_liquid_in_content
+    before_create :process_liquid_in_template_params
   end
 
   private
@@ -35,4 +36,61 @@ module Liquidable
     # We don't want to process liquid in code blocks
     content.gsub(/`(.*?)`/m, '{% raw %}`\\1`{% endraw %}')
   end
+
+  def process_liquid_in_template_params
+    return unless template_params_present? && liquid_processable_template_params?
+
+    processed_params = process_liquid_in_hash(template_params_data['processed_params'])
+
+    # Update the additional_attributes with processed template_params
+    self.additional_attributes = additional_attributes.merge(
+      'template_params' => template_params_data.merge('processed_params' => processed_params)
+    )
+  rescue Liquid::Error
+    # If there is an error in the liquid syntax, we don't want to process it
+  end
+
+  def template_params_present?
+    additional_attributes&.dig('template_params', 'processed_params').present?
+  end
+
+  def liquid_processable_template_params?
+    message_type == 'outgoing' || message_type == 'template'
+  end
+
+  def template_params_data
+    additional_attributes['template_params']
+  end
+
+  def process_liquid_in_hash(hash)
+    return hash unless hash.is_a?(Hash)
+
+    hash.transform_values { |value| process_liquid_value(value) }
+  end
+
+  def process_liquid_value(value)
+    case value
+    when String
+      process_liquid_string(value)
+    when Hash
+      process_liquid_in_hash(value)
+    when Array
+      process_liquid_array(value)
+    else
+      value
+    end
+  end
+
+  def process_liquid_array(array)
+    array.map { |item| process_liquid_value(item) }
+  end
+
+  def process_liquid_string(string)
+    return string if string.blank?
+
+    template = Liquid::Template.parse(string)
+    template.render(message_drops)
+  rescue Liquid::Error
+    string
+  end
 end
diff --git a/spec/models/concerns/liquidable_shared.rb b/spec/models/concerns/liquidable_shared.rb
index 8df526a2f..7b9f856cd 100644
--- a/spec/models/concerns/liquidable_shared.rb
+++ b/spec/models/concerns/liquidable_shared.rb
@@ -69,4 +69,159 @@ shared_examples_for 'liqudable' do
       end
     end
   end
+
+  context 'when liquid is present in template_params' do
+    let(:contact) do
+      create(:contact, name: 'john', email: 'john@example.com', phone_number: '+912883', custom_attributes: { customer_type: 'platinum' })
+    end
+    let(:conversation) { create(:conversation, id: 1, contact: contact, custom_attributes: { priority: 'high' }) }
+
+    context 'when message is outgoing with template_params' do
+      let(:message) { build(:message, conversation: conversation, message_type: 'outgoing') }
+
+      it 'replaces liquid variables in template_params body' do
+        message.additional_attributes = {
+          'template_params' => {
+            'name' => 'greet',
+            'category' => 'MARKETING',
+            'language' => 'en',
+            'processed_params' => {
+              'body' => {
+                'customer_name' => '{{contact.name}}',
+                'customer_email' => '{{contact.email}}'
+              }
+            }
+          }
+        }
+        message.save!
+
+        body_params = message.additional_attributes['template_params']['processed_params']['body']
+        expect(body_params['customer_name']).to eq 'John'
+        expect(body_params['customer_email']).to eq 'john@example.com'
+      end
+
+      it 'replaces liquid variables in nested template_params' do
+        message.additional_attributes = {
+          'template_params' => {
+            'name' => 'test_template',
+            'processed_params' => {
+              'header' => {
+                'media_url' => 'https://example.com/{{contact.name}}.jpg'
+              },
+              'body' => {
+                'customer_name' => '{{contact.name}}',
+                'priority' => '{{conversation.custom_attribute.priority}}'
+              },
+              'footer' => {
+                'company' => '{{account.name}}'
+              }
+            }
+          }
+        }
+        message.save!
+
+        processed = message.additional_attributes['template_params']['processed_params']
+        expect(processed['header']['media_url']).to eq 'https://example.com/John.jpg'
+        expect(processed['body']['customer_name']).to eq 'John'
+        expect(processed['body']['priority']).to eq 'high'
+        expect(processed['footer']['company']).to eq conversation.account.name
+      end
+
+      it 'handles arrays in template_params' do
+        message.additional_attributes = {
+          'template_params' => {
+            'name' => 'test_template',
+            'processed_params' => {
+              'buttons' => [
+                { 'type' => 'url', 'parameter' => 'https://example.com/{{contact.name}}' },
+                { 'type' => 'text', 'parameter' => 'Hello {{contact.name}}' }
+              ]
+            }
+          }
+        }
+        message.save!
+
+        buttons = message.additional_attributes['template_params']['processed_params']['buttons']
+        expect(buttons[0]['parameter']).to eq 'https://example.com/John'
+        expect(buttons[1]['parameter']).to eq 'Hello John'
+      end
+
+      it 'handles custom attributes in template_params' do
+        message.additional_attributes = {
+          'template_params' => {
+            'name' => 'test_template',
+            'processed_params' => {
+              'body' => {
+                'customer_type' => '{{contact.custom_attribute.customer_type}}',
+                'priority' => '{{conversation.custom_attribute.priority}}'
+              }
+            }
+          }
+        }
+        message.save!
+
+        body_params = message.additional_attributes['template_params']['processed_params']['body']
+        expect(body_params['customer_type']).to eq 'platinum'
+        expect(body_params['priority']).to eq 'high'
+      end
+
+      it 'handles missing email with default filter in template_params' do
+        contact.update!(email: nil)
+        message.additional_attributes = {
+          'template_params' => {
+            'name' => 'test_template',
+            'processed_params' => {
+              'body' => {
+                'customer_email' => '{{ contact.email | default: "no-email@example.com" }}'
+              }
+            }
+          }
+        }
+        message.save!
+
+        body_params = message.additional_attributes['template_params']['processed_params']['body']
+        expect(body_params['customer_email']).to eq 'no-email@example.com'
+      end
+
+      it 'handles broken liquid syntax in template_params gracefully' do
+        message.additional_attributes = {
+          'template_params' => {
+            'name' => 'test_template',
+            'processed_params' => {
+              'body' => {
+                'broken_liquid' => '{{contact.name}  {{invalid}}'
+              }
+            }
+          }
+        }
+        message.save!
+
+        body_params = message.additional_attributes['template_params']['processed_params']['body']
+        expect(body_params['broken_liquid']).to eq '{{contact.name}  {{invalid}}'
+      end
+
+      it 'does not process template_params when message is incoming' do
+        incoming_message = build(:message, conversation: conversation, message_type: 'incoming')
+        incoming_message.additional_attributes = {
+          'template_params' => {
+            'name' => 'test_template',
+            'processed_params' => {
+              'body' => {
+                'customer_name' => '{{contact.name}}'
+              }
+            }
+          }
+        }
+        incoming_message.save!
+
+        body_params = incoming_message.additional_attributes['template_params']['processed_params']['body']
+        expect(body_params['customer_name']).to eq '{{contact.name}}'
+      end
+
+      it 'does not process template_params when not present' do
+        message.additional_attributes = { 'other_data' => 'test' }
+        expect { message.save! }.not_to raise_error
+      end
+    end
+  end
 end