shopify-metafields

• Namespace: Grouping folder (e.g., my_app, global).
• Key: Specific field name (e.g., washing_instructions).
• Type: Data type (e.g., single_line_text_field, number_integer, json).
• Owner: The resource attaching the data (Product ID, Shop ID).

Always use Metafield Definitions (pinned metafields) when possible. This integrates them into the Admin UI and ensures standard processing.

• Create: Settings > Custom Data > [Resource] > Add definition.
• Access: namespace.key

To display metafield data on the Storefront:

```liquid

Washing: {{ product.metafields.my_app.washing_instructions }}

{% assign file = product.metafields.my_app.size_chart.value %}

{% if product.metafields.my_app.instructions != blank %}

...

{% endif %}

```

```graphql

query {

product(id: "gid://shopify/Product/123") {

title

metafield(namespace: "my_app", key: "instructions") {

value

type

}

}

}

```

To create or update a metafield, use metafieldsSet.

```graphql

mutation metafieldsSet($metafields: [MetafieldsSetInput!]!) {

metafieldsSet(metafields: $metafields) {

metafields {

id

namespace

key

value

}

userErrors {

field

message

}

}

}

/ Variables /

{

"metafields": [

{

"ownerId": "gid://shopify/Product/123",

"namespace": "my_app",

"key": "instructions",

"type": "single_line_text_field",

"value": "Wash cold, tumble dry."

}

]

}

```

If you want data to be hidden from other apps and the storefront, use Private Metafields. Note: These cannot be accessed via Liquid directly.

• Use privateMetafield queries/mutations.
• Requires explicit read_private_metafields / write_private_metafields scope (rarely used now, app_data metafields are preferred for app-specific valid storage).