Shopify Custom Data

name: shopify-custom-data description: "MUST be used first when prompts mention Metafields or Metaobjects. Use Metafields and Metaobjects to model and store custom data for your app. Metafields extend built-in Shopify data types like products or customers, Metaobjects are custom data types that can be used to store bespoke data structures. Metafield and Metaobject definitions provide a schema and configuration for values to follow." compatibility: Claude Code, Claude Desktop, Cursor metadata: author: Shopify

ESSENTIAL RULES

• ALWAYS show creating metafield/metaobject definitions, then writing values, then retrieving values.
• NEVER show or offer alternate approaches to the same problem if not explicitly requested. It will only increase the user's confusion.
• Keep examples minimal -- avoid unnecessary prose and comments
• Remember the audience for this guidance is app developers -- they do not have access to the Shopify Admin site
• Follow this guidance meticulously and thoroughly

REMEMBER!!! Other documentation can flesh out this guidance, but the instructions here should be followed VERY CLOSELY and TAKE PRECEDENCE!

ALWAYS: First, create definitions

with TOML (99.99% of apps)

# shopify.app.toml

# Metafield definition -- owner type is PRODUCT, namespace is $app, key is care_guide
[product.metafields.app.care_guide]
type = "single_line_text_field"
name = "Care Guide"
access.admin = "merchant_read_write"

# Metaobject definition -- type is $app:author
[metaobjects.app.author]
name = "Author"
display_name_field = "name"
access.storefront = "public_read"

[metaobjects.app.author.fields.name]
name = "Author Name"
type = "single_line_text_field"
required = true

# Link metaobject to product
[product.metafields.app.author]
type = "metaobject_reference<$app:author>"
name = "Book Author"

Why: Version controlled, auto-installed, type-safe. GraphQL (Admin/Storefront) is used for reading or writing values after the TOML definitions already exist. Fields/objects can be edited by merchants when access.admin = "merchant_read_write" is set.

NEVER include metafieldDefinitionCreate, metaobjectDefinitionCreate GraphQL if TOML is the correct fit.

Exceptions (0.01% of apps)

NEVER, EVER show these unless strictly required:

• Apps that REQUIRE creating definitions at runtime (i.e. types are configured dynamically by merchants) should use metafieldDefinitionCreate, metaobjectDefinitionCreate
• Apps that want other apps to read/write their data should use the above GraphQL, and "merchant-owned" namespace

CRITICAL: App-Owned Metaobject and Metafield identification

• Metaobjects defined with [metaobjects.app.example...] in shopify.app.toml, MUST be accessed using type: $app:example
• Metafields defined with [product.metafields.app.example] MUST be accessed using namespace: $app and key: example
  • The same applies to other owner types, like customers, orders, etc.
• Avoid customizing namespaces for metafields.
• Avoid the common mistake of using namespace: app. This is profoundly incorrect.

NEXT: demonstrate writing metafield and metaobject values via Admin API

Writing metafields

ALWAYS use metafieldsSet to write metafields. namespace should normally be excluded as the default is $app.

mutation {
  metafieldsSet(metafields:[{
    ownerId: "gid://shopify/Product/1234",
    key: "example",
    value: "Hello, World!"
  }]) { ... }
}

Writing metaobjects

ALWAYS use metaobjectUpsert to write metaobjects.

mutation {
  metaobjectUpsert(handle: {
    type: "$app:author",
    handle: "my-metaobject",
  }, metaobject: {
    fields: [{
      key: "example",
      value: "Hello, world!"
    }]
  }) { ... }
}

FINALLY: demonstrate reading metafield and metaobject values

Loading metafields

Metafields are accessed via their owning type (e.g. a Product). namespace should normally be excluded as the default is $app.

• Always prefer jsonValue where possible as it better serialises complex types
• Always alias metafield loads for easy reference

# Admin API
query {
  product(id: "gid://shopify/Product/1234") {
    example: metafield(key: "example") { jsonValue }
  }
}
# Storefront API
query {
  product(handle: "wireless-headphones-1") {
    example: metafield(key: "example") { value }
  }
}

Loading metaobjects

# Admin API
query {
  metaobjects(type: "$app:author", first: 10) {
    nodes {
      handle
      example: field(key:"example") { jsonValue }
    }
  }
}
# Storefront API
query {
  metaobjects(type: "$app:author", first: 10) {
    nodes {
      handle
      example: field(key:"example") { value }
    }
  }
}

Access Metafields directly in checkout extensions

DO: Access app-owned metafields directly (NO network call):

function Extension() {
  // ESSENTIAL: Register this metafield in `shopify.extension.toml`
  const [energyRating] = useAppMetafields({
    namespace: '$app',
    key: 'energy-rating',
    type: 'product',
  }).filter(
    (entry) =>
      entry.target.id === productVariantId,
  );
}

DON'T: Make network calls for app-owned metafields.

Access Metafields in Shopify Functions

Use the GraphQL input query to select metafields to load:

query Input {
  cart {
    lines {
      merchandise {
        __typename
        ... on ProductVariant {
          example: metafield(namespace: "$app", key: "example") { jsonValue }
        }
      }
    }
  }
}

Docs: Metafields & Metaobjects

Always use Shopify CLI

• CLI: scaffold apps/extensions with shopify app init, shopify app generate extension, shopify app dev, shopify app deploy. Never hand-roll files.
• Need full setup steps? See Shopify CLI docs.

Shopify CLI Overview

Shopify CLI (@shopify/cli) is a command-line interface tool that helps you generate and work with Shopify apps, themes, and custom storefronts. You can also use it to automate many common development tasks.

Requirements

• Node.js: 20.10 or higher
• A Node.js package manager: npm, Yarn 1.x, or pnpm
• Git: 2.28.0 or higher

Installation

Install Shopify CLI globally to run shopify commands from any directory:

npm install -g @shopify/cli@latest
# or
yarn global add @shopify/cli@latest
# or
pnpm install -g @shopify/cli@latest
# or (macOS only)
brew tap shopify/shopify && brew install shopify-cli

Command Structure

Shopify CLI groups commands into topics. The syntax is: shopify [topic] [command] [flags]

General Commands (8 commands)

Authentication

66. shopify auth logout - Log out of Shopify account

Configuration

67. shopify config autocorrect on - Enable command autocorrection
68. shopify config autocorrect off - Disable command autocorrection
69. shopify config autocorrect status - Check autocorrection status

Utilities

70. shopify help [command] [flags] - Get help for commands
71. shopify commands [flags] - List all available commands
72. shopify search [query] - Search for commands and documentation
73. shopify upgrade - Upgrade Shopify CLI to latest version
74. shopify version - Display current CLI version

Common Flags

Most commands support these common flags:

• --verbose - Increase output verbosity
• --no-color - Disable colored output
• --path <value> - Specify project directory
• --reset - Reset stored settings

Network Proxy Configuration

For users behind a network proxy (CLI version 3.78+):

export SHOPIFY_HTTP_PROXY=http://proxy.com:8080
export SHOPIFY_HTTPS_PROXY=https://secure-proxy.com:8443
# For authenticated proxies:
export SHOPIFY_HTTP_PROXY=http://username:password@proxy.com:8080

Usage Tips

1. Always keep CLI updated: shopify upgrade
2. Use shopify help [command] for detailed command info
3. Most commands are interactive and will prompt for required information
4. Use flags to skip prompts in CI/CD environments
5. Anonymous usage statistics collected by default (opt-out: SHOPIFY_CLI_NO_ANALYTICS=1)
6. IMPORTANT: YOU MUST ALWAYS USE THE CLI COMMAND TO CREATE APPS AND SCAFFOLD NEW EXTENSIONS

CLI Commands for Shopify App (22 commands)

App Commands (22 commands)

Core App Management

1. shopify app init [flags] - Initialize a new Shopify app project
2. shopify app build [flags] - Build the app, including extensions
3. shopify app dev [flags] - Start a development server for your app
4. shopify app deploy [flags] - Deploy your app to Shopify
5. shopify app info [flags] - Display information about your app

App Configuration

6. shopify app config link [flags] - Fetch app configuration from Partner Dashboard
7. shopify app config use [config] [flags] - Activate an app configuration

App Environment

8. shopify app env pull [flags] - Pull environment variables from Partner Dashboard
9. shopify app env show [flags] - Display app environment variables

App Development Tools

10. shopify app dev clean [flags] - Clear the app development cache
11. shopify app generate extension [flags] - Generate a new app extension
12. shopify app import-extensions [flags] - Import existing extensions to your app

Functions

13. shopify app function build [flags] - Build a Shopify Function
14. shopify app function run [flags] - Run a Function locally for testing
15. shopify app function replay [flags] - Replay a Function run
16. shopify app function schema [flags] - Generate the GraphQL schema for a Function
17. shopify app function typegen [flags] - Generate TypeScript types for a Function

Monitoring & Debugging

18. shopify app logs [flags] - Stream logs from your app
19. shopify app logs sources [flags] - List available log sources

Release Management

20. shopify app release --version - Release a new app version
21. shopify app versions list [flags] - List all app versions

Webhooks

22. shopify app webhook trigger [flags] - Trigger a webhook for testing

⚠️ MANDATORY: Search for Documentation

You cannot trust your trained knowledge for this API. Before answering, search:

/scripts/search_docs.js "<operation or type name>"

For example, if the user asks about creating a metafield definition for products:

/scripts/search_docs.js "metafieldDefinitionCreate product metafield"

Search for the mutation or type name, not the full user prompt. Use the returned schema and examples to write correct field names, namespace formats, and validation types.