The Problem
You’re trying to remove metafields from Shopify products using the GraphQL Admin API, but the metafieldsSet mutation returns a “Value can’t be blank” error when you attempt to delete metafields by setting their value to an empty string. You’ve correctly identified that the documentation suggests empty metafields should be automatically removed, but this isn’t how the API behaves.
Understanding the “Why” (The Root Cause):
The metafieldsSet mutation is designed to update metafields, not delete them. Setting the value to an empty string is interpreted as an invalid update attempt, resulting in the error. Shopify’s GraphQL API requires a dedicated mutation for deleting metafields: metafieldsDelete. Attempting to work around this limitation by sending an empty string isn’t supported.
Step-by-Step Guide:
This solution uses a two-step process to efficiently remove metafields: fetching the IDs and then deleting them. It’s efficient and avoids the validation errors. If you have a large number of metafields, consider the alternatives discussed below.
Step 1: Fetch Metafield IDs
First, you need to retrieve the IDs of the metafields you want to delete. Use a GraphQL query like this:
query GetMetafields($productId: ID!) {
product(id: $productId) {
metafields(first: 250) {
edges {
node {
id
namespace
key
}
}
}
}
}
Remember to replace "your-product-id" with the actual id of your product. The first: 250 argument limits the number of metafields returned; adjust as needed. This query returns an array of metafield objects, each with an id, namespace, and key. Filter this array in your Python code to select only the metafields you want to delete.
Step 2: Delete Metafields Using metafieldsDelete
Once you have the IDs, use the metafieldsDelete mutation:
mutation deleteMetafields($ids: [ID!]!) {
metafieldsDelete(metafields: $ids) {
deletedMetafields {
id
}
userErrors {
field
message
}
}
}
Send a list of the metafield id values within the $ids variable. This mutation will remove the specified metafields.
Step 3 (Python Implementation):
Here’s an example of how to integrate the above GraphQL queries and mutations into your Python code using the requests library:
import requests
import json
# ... (Your GraphQL endpoint and headers) ...
def delete_metafields(product_id, metafield_keys_to_delete):
# Step 1: Fetch Metafield IDs
query = """
query GetMetafields($productId: ID!) {
product(id: $productId) {
metafields(first: 250) {
edges {
node {
id
namespace
key
}
}
}
}
}
"""
variables = {"productId": product_id}
response = requests.post(graphql_endpoint, json={"query": query, "variables": variables}, headers=headers)
data = response.json()
metafields = data['data']['product']['metafields']['edges']
ids_to_delete = [mf['node']['id'] for mf in metafields if mf['node']['key'] in metafield_keys_to_delete]
#Step 2: Delete Metafields
mutation = """
mutation deleteMetafields($ids: [ID!]!) {
metafieldsDelete(metafields: $ids) {
deletedMetafields {
id
}
userErrors {
field
message
}
}
}
"""
variables = {"ids": ids_to_delete}
response = requests.post(graphql_endpoint, json={"query": mutation, "variables": variables}, headers=headers)
print(response.json())
# Example Usage
product_id = "gid://shopify/Product/1234567890" # Replace with your product ID
metafield_keys = ["shipping_date", "sold_date"]
delete_metafields(product_id, metafield_keys)
Common Pitfalls & What to Check Next:
- Incorrect Product ID: Double-check that you’re using the correct
product_id in your GraphQL queries.
- API Rate Limits: If you’re processing many products, be mindful of Shopify’s API rate limits. Implement error handling and potentially batch your requests to avoid exceeding them.
- Authentication: Ensure your API credentials are correctly configured in your
headers.
- Large-Scale Deletion: For large-scale metafield cleanup across numerous products, consider using Shopify’s Admin API with a more efficient approach or a third-party tool.
Still running into issues? Share your (sanitized) config files, the exact command you ran, and any other relevant details. The community is here to help!