Custom Mapper — advanced data mapping and fallback logic

Updated May 4, 2026

The standard Junipeer configuration covers the most common data mapping scenarios out of the box. For cases that require more control — custom field routing, fallback logic, or data pulled from metafields — Junipeer provides the Custom Mapper (also called the Rule Builder).

The Custom Mapper is configured by the Junipeer team based on your requirements. You describe what you need; we set it up.

What it handles

Fallback logic for missing data

Some integrations encounter orders where expected fields are missing or empty. A common example is a B2B order that has no billing address in the sales order.

The Fortnox API requires a valid billing address to create an invoice. When the billing address is absent, the Custom Mapper can define a fallback sequence — for example:

  1. Use the billing address if present

  2. Fall back to the shipping address

  3. Fall back to a specific metafield on the order

This logic runs automatically on every order, so your sync does not break when data is incomplete.

Metafield mapping to ERP fields

Shopify and other e-commerce platforms store additional data in metafields — structured custom attributes attached to orders, customers, or products. This data is not mapped by default but can be routed to specific fields in your ERP or accounting system via the Custom Mapper.

Common use cases:

  • Invoice field population — pull a value from an order metafield and write it to a specific field in a Fortnox invoice template

  • Custom reference fields — map an internal reference, purchase order number, or project code from a metafield to the corresponding field in Fortnox

  • Dual email routing — if your B2B customers have both a buyer/seller contact email and a separate finance department email, the Custom Mapper can route each to the correct field. For example, the buyer email goes to the customer card in Fortnox, while the finance email is written to the invoice recipient field

Other Custom Mapper use cases

The Custom Mapper is flexible and handles a wide range of non-standard requirements. Other examples include:

  • Conditional logic based on order tags, customer type, or market

  • Data transformation (e.g. reformatting a date, splitting a field, concatenating values)

  • Writing a fixed value to a field regardless of what comes from the source system

How to request Custom Mapper configuration

Custom Mapper setups are handled by the Junipeer team during onboarding or as a post-go-live configuration request. To get started:

  1. Describe the field or data you want to map and where it should go

  2. Include any relevant metafield keys, field names, or example values

  3. Send the request to your Junipeer onboarding contact or support@junipeer.io

We will confirm the specific setup before applying it to your live integration.


For general configuration, see Fortnox — Configuration in Junipeer. For troubleshooting, contact support@junipeer.io.

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