gabrielmoreira Shopify Metafields & Metaobjects
Overview
Metafields attach key-value custom data to existing resources (products, variants, orders, customers). Metaobjects define entirely new content types with custom schemas. Together they replace the need for external databases for most custom data needs.
Prerequisites
- Completed
shopify-install-authsetup - Access scopes:
read_metaobjects,write_metaobjects,read_metaobject_definitions,write_metaobject_definitions - Metafield scopes per resource:
read_products/write_productsfor product metafields, etc.
Instructions
Step 1: Define a Metafield on Products
Use metafieldDefinitionCreate with namespace, key, type, and ownerType:
await client.request(METAFIELD_DEFINITION_CREATE, {
variables: {
definition: {
namespace: "custom",
key: "care_instructions",
name: "Care Instructions",
type: "multi_line_text_field", // See references/metafield-types.md
ownerType: "PRODUCT",
pin: true, // Show in admin UI
},
},
});
// Always check userErrors — Shopify returns 200 even on validation failures
Step 2: Set Values in Batch with metafieldsSet
await client.request(METAFIELDS_SET, {
variables: {
metafields: [
{
ownerId: "gid://shopify/Product/123456",
namespace: "custom",
key: "care_instructions",
value: "Machine wash cold.\nTumble dry low.",
type: "multi_line_text_field",
},
// Up to 25 metafields per call
],
},
});
Step 3: Create a Metaobject Definition
Define a custom content type (e.g., "Designer" with typed fields):
await client.request(METAOBJECT_DEFINITION_CREATE, {
variables: {
definition: {
type: "$app:designer",
displayNameKey: "name",
fieldDefinitions: [
{ key: "name", name: "Name", type: "single_line_text_field" },
{ key: "bio", name: "Bio", type: "multi_line_text_field" },
{ key: "photo", name: "Photo", type: "file_reference" },
],
access: { storefront: "PUBLIC_READ" },
},
},
});
Step 4: Create Metaobject Instances
await client.request(METAOBJECT_CREATE, {
variables: {
metaobject: {
type: "$app:designer",
handle: "jane-doe",
fields: [
{ key: "name", value: "Jane Doe" },
{ key: "bio", value: "Award-winning textile designer." },
],
},
},
});
See metafield-types.md for all types, toml-config.md for app config, and bulk-metafield-ops.md for bulk operations.
Output
- Metafield definitions registered on target resource types
- Metafield values set on individual resources (batch supported, max 25 per call)
- Custom metaobject types with typed field schemas
- Metaobject instances queryable via Storefront and Admin APIs
Error Handling
| Error | Cause | Solution |
|---|---|---|
TAKEN |
Namespace + key already exists on this owner type | Use metafieldDefinitionUpdate or choose a different key |
INVALID_TYPE |
Type string not in Shopify's registry | Check metafield-types.md |
INVALID_VALUE |
Value doesn't match declared type | Cast value to correct format before setting |
TOO_LONG |
Value exceeds type limit (512KB for text types) | Truncate or switch to multi_line_text_field |
Examples
Adding Care Instructions to All Products
Define a "care_instructions" metafield on the PRODUCT owner type, then bulk-set values across hundreds of products in batches of 25.
See Bulk Metafield Ops for the batch set/delete operations.
Choosing the Right Metafield Type
You need to store a color swatch, a date range, or a product reference. Pick the correct type from Shopify's type registry.
See Metafield Types for the complete type list with value format examples.
Declaring Metafields in App Configuration
Define metafield and metaobject schemas in shopify.app.toml so they deploy automatically with the app instead of making API calls.
See TOML Config for the app configuration syntax.
Resources
- Metafield Definition API
- metafieldsSet Mutation
- Metaobject API Guide
- Metafield Types Reference