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Templates and Data Binding

Overview

Build a Doc uses a template-driven approach to document generation. Templates define the structure and layout of your documents, while data binding connects your data sources to placeholders within the template.

What is a Template?

A template is a document that serves as a blueprint for your generated output. It contains:

  • Static Content - Text, images, tables, and formatting that remain unchanged
  • Template Expressions - Placeholders that are replaced with data at runtime
  • Control Logic - Conditionals and loops that control document flow

Supported Template Types

Template TypeFile FormatsTemplate Syntax
Word.doc, .docx<<[expression]>>
Excel.xls, .xlsx<<[expression]>>
HTML.html{{expression}}

For additional information on template syntax, see the relevant template-language guides:

Data Binding Fundamentals

Data binding is the process of connecting template expressions to values in your data source.

Basic Binding

The simplest binding references a property directly:

Data Source:

[
  {
    "Name": "Customer",
    "Data": {
      "CustomerName": "John Smith"
    }
  }
]

Template:

Customer: <<[CustomerName]>>

Output:

Customer: John Smith

Nested Property Binding

Access properties within objects using dot notation:

Data Source:

[
  {
    "Name": "Customer",
    "Data": {
      "Name": "John Smith",
      "Address": {
        "City": "London"
      }
    }
  }
]

Template:

<<[Customer.Name]>> lives in <<[Customer.Address.City]>>

Output:

John Smith lives in London

Data Source Naming

When calling a Build a Doc action, you specify:

  • Data source Name - The identifier used in templates
  • Data source Data - The actual data
  • Data source Format - JSON, XML, or CSV

For detailed guidance on formatting your JSON data correctly, see Structure JSON Data.

The Name becomes the root accessor in your template:

Action Configuration:

Name: Invoice
Data: { "Number": "INV-001", "Total": 500 }

Template Access:

Invoice #<<[Invoice.Number]>> - Total: £<<[Invoice.Total]>>

Multiple Data Sources

You can provide multiple data sources to a single action:

NameData
Company{ "Name": "Acme Ltd" }
Invoice{ "Number": "001", "Items": [...] }
Metadata{ "GeneratedDate": "2025-01-22" }

Template:

<<[Company.Name]>>
Invoice: <<[Invoice.Number]>>
Generated: <<[Metadata.GeneratedDate]>>

Array Binding

Bind to arrays using loops:

Data Source:

[
  {
    "Name": "Catalogue",
    "Data": {
      "Products": [
        { "Name": "Widget A", "Price": 10.0 },
        { "Name": "Widget B", "Price": 15.0 }
      ]
    }
  }
]

Template:

<<foreach [product in Catalogue]>>
- <<[product.Name]>>: £<<[product.Price]>>
<</foreach>>

Output:

- Widget A: £10.00
- Widget B: £15.00

Null and Missing Values

When a referenced property doesn’t exist or is null:

  • Default behaviour - Missing or null values evaluate to null/undefined; if blocks that reference them will not render and standalone placeholders produce no output.
  • With Error Display - When inline error display is enabled, template errors are shown in the output document to help debugging.

For handling optional data, use conditionals and null-coalescing operators: