Metafields

Overview

Metafields provide a flexible, type-safe system for adding custom structured data to Spree resources. Unlike metadata which is simple JSON storage, metafields are schema-defined with strong typing, validation, and visibility controls.

Use metafields for:

• Product specifications (manufacturer, material, dimensions)
• Custom business logic fields
• Integration data from external systems
• Order-specific custom attributes

Architecture

erDiagram
    MetafieldDefinition ||--o{ Metafield : "defines schema for"
    Product ||--o{ Metafield : "has many"
    Variant ||--o{ Metafield : "has many"
    Order ||--o{ Metafield : "has many"

    MetafieldDefinition {
        string namespace
        string key
        string name
        string metafield_type
        string resource_type
        string display_on
    }

    Metafield {
        string type
        text value
        string resource_type
    }

flowchart LR
    subgraph Definition
        A[MetafieldDefinition] --> B["namespace: properties"]
        A --> C["key: manufacturer"]
        A --> D["type: ShortText"]
        A --> E["resource_type: Product"]
        A --> F["display_on: both"]
    end

    subgraph Instance
        G[Metafield] --> H["value: Wilson"]
        G --> I["resource: Product #1"]
    end

    A -.->|"defines schema"| G

• MetafieldDefinition — the blueprint that defines the data type, target resource, and visibility
• Metafield — stores the actual value for a specific resource instance

Data Types

Visibility Control

Metafields support three visibility levels via the display_on attribute:

Supported Resources

Metafields can be attached to most Spree resources including Products, Variants, Orders, Line Items, Taxons, Payments, Shipments, Gift Cards, Store Credits, and more.

Namespaces

Namespaces organize metafields into logical groups and prevent key conflicts:

Store API

Metafields with display_on set to both or front_end are included in Store API responses when you request the custom_fields expand:

const product = await client.products.get('spree-tote', {
  expand: ['custom_fields'],
})

product.custom_fields?.forEach(field => {
  console.log(field.key)   // "properties.manufacturer"
  console.log(field.label) // "Manufacturer"
  console.log(field.value) // "Wilson"
  console.log(field.type)  // "short_text"
})

curl 'https://api.mystore.com/api/v3/store/products/spree-tote?expand=custom_fields' \
  -H 'X-Spree-Api-Key: pk_xxx'

Response:

{
  "id": "prod_86Rf07xd4z",
  "name": "Spree T-Shirt",
  "custom_fields": [
    {
      "id": "cf_k5nR8xLq",
      "label": "Manufacturer",
      "key": "properties.manufacturer",
      "type": "short_text",
      "value": "Wilson"
    },
    {
      "id": "cf_m3Rp9wXz",
      "label": "Material",
      "key": "properties.material",
      "type": "short_text",
      "value": "100% Cotton"
    }
  ]
}

Admin Panel Management

Managing Definitions

Navigate to Settings → Metafield Definitions in the Admin Panel to create and manage metafield definitions. Select the resource type, enter namespace and key, choose the data type, and set visibility.

Managing Values

When editing a resource (e.g., a product), metafields appear in a dedicated section. The admin panel automatically builds forms for all defined metafields.

Metafields vs Metadata

Spree has two permanent, complementary systems for custom data — metadata for machines, metafields for humans. They serve different purposes and are not interchangeable. Neither is going away.

Use Metafields when you need type validation, visibility control, admin UI forms, or organized namespacing.

Use Metadata for external system IDs, tracking attribution, syncing with integrations, or simple write-and-forget data that only backend systems need to read.

Related Documentation

• Metadata — Simple key-value metadata
• Products — Product catalog
• Events — Subscribe to metafield events