Mechanic is a development and ecommerce automation platform for Shopify. :)
Useful for multiple price points, or for offering customizations of the same item, this task lets you offer multiple variant listings for what is ultimately the same stock. A purchase of a particular variant results in the inventory for all other variants, for the same product, being lowered by the amount ordered.
Runs Occurs when a user manually triggers the task, Occurs every 10 minutes, and Occurs whenever user/sync_variant_inventory/set_cache is triggered. Configuration includes product tags to monitor, product types to monitor, and only sync active products.
Useful for multiple price points, or for offering customizations of the same item, this task lets you offer multiple variant listings for what is ultimately the same stock. A purchase of a particular variant results in the inventory for all other variants, for the same product, being lowered by the amount ordered.
Mechanic is designed to benefit everybody: merchants, customers, developers, agencies, Shopifolks, everybody.
That’s why we make it easy to configure automation without code, why we make it easy to tweak the underlying code once tasks are installed, and why we publish it all here for everyone to learn from.
(By the way, have you seen our documentation? Have you joined the Slack community?)
mechanic/user/trigger mechanic/scheduler/10min user/sync_variant_inventory/set_cache
{% assign product_tags = options.product_tags_to_monitor__array %}
{% assign product_types = options.product_types_to_monitor__array %}
{% assign only_sync_active_products = options.only_sync_active_products__boolean %}
{% assign primary_location = shop.locations[shop.primary_location_id] %}
{% if product_tags == blank and product_types == blank %}
{% error "You must choose to monitor products either by tags or types." %}
{% elsif product_tags != blank and product_types != blank %}
{% error "Choose to monitor products either by tags or types, but not both." %}
{% endif %}
{% if event.topic == "mechanic/user/trigger" or event.topic contains "mechanic/scheduler/" %}
{% comment %}
-- run query for all variants matched by product tags or types
{% endcomment %}
{% assign variants_by_product = hash %}
{% assign cursor = nil %}
{% assign search_query_parts = array %}
{% for product_type in product_types %}
{% assign search_query_parts[search_query_parts.size] = product_type | json | prepend: "product_type:" %}
{% endfor %}
{% for product_tag in product_tags %}
{% assign search_query_parts[search_query_parts.size] = product_tag | json | prepend: "tag:" %}
{% endfor %}
{% capture search_query -%}
location_id:{{ shop.primary_location_id }} ({{ search_query_parts | join: " OR " }}) managed:true
{%- endcapture %}
{% if only_sync_active_products %}
{% assign search_query = search_query | append: " product_status:active" %}
{% endif %}
{% for n in (0..200) %}
{% capture query %}
query {
productVariants(
first: 150
query: {{ search_query | json }}
after: {{ cursor | json }}
) {
pageInfo {
hasNextPage
endCursor
}
nodes {
id
inventoryItem {
id
inventoryLevel(locationId: {{ primary_location.admin_graphql_api_id | json }}) {
quantities(names: "available") {
name
quantity
}
}
}
product {
id
}
}
}
}
{% endcapture %}
{% assign result = query | shopify %}
{% if event.preview %}
{% capture result_json %}
{
"data": {
"productVariants": {
"nodes": [
{
"id": "gid://shopify/ProductVariant/1234567890",
"inventoryItem": {
"id": "gid://shopify/InventoryItem/1234567890",
"inventoryLevel": {
"quantities": [
{
"name": "available",
"quantity": 30
}
]
}
},
"product": {
"id": "gid://shopify/Product/1234567890"
}
},
{
"id": "gid://shopify/ProductVariant/2345678901",
"inventoryItem": {
"id": "gid://shopify/InventoryItem/2345678901",
"inventoryLevel": {
"quantities": [
{
"name": "available",
"quantity": {% if event.topic == "mechanic/user/trigger" %}30{% else %}31{% endif %}
}
]
}
},
"product": {
"id": "gid://shopify/Product/1234567890"
}
}
]
}
}
}
{% endcapture %}
{% assign result = result_json | parse_json %}
{% endif %}
{% for variant in result.data.productVariants.nodes %}
{% assign variants_by_product[variant.product.id]
= variants_by_product[variant.product.id]
| default: array
| push: variant
%}
{% endfor %}
{% if result.data.productVariants.pageInfo.hasNextPage %}
{% assign cursor = result.data.productVariants.pageInfo.endCursor %}
{% else %}
{% break %}
{% endif %}
{% endfor %}
{% if variants_by_product == blank %}
{% error
message: "No matching product variants found! Check your product tag or type settings for this task.",
search_query: search_query
%}
{% break %}
{% endif %}
{% elsif event.topic == "user/sync_variant_inventory/set_cache" %}
{% comment %}
-- this user event is called from the scheduler event, to process any products without a cache entry
{% endcomment %}
{% if event.data.products_missing_cache == blank %}
{% error "No products with missing cache were passed to this event." %}
{% endif %}
{% assign variants_by_product = event.data.products_missing_cache %}
{% endif %}
{% if event.topic == "mechanic/user/trigger" or event.topic == "user/sync_variant_inventory/set_cache" %}
{% comment %}
-- this event is run manually for initial setup, but will also be triggered via a custom event to handle any products that don't yet have a cache setting (typically new products, but can be existing ones if their cache expires or if the task configuration is changed)
{% endcomment %}
{% assign products_out_of_sync = array %}
{% for pair in variants_by_product %}
{% assign product_id = pair[0] %}
{% assign variants = pair[1] %}
{% assign available_quantites = array %}
{% for variant in variants %}
{% assign available_quantites = available_quantites | push: variant.inventoryItem.inventoryLevel.quantities.first.quantity %}
{% endfor %}
{% assign inventory_total = available_quantites | sum %}
{% assign expected_inventory_total = available_quantites.first | times: available_quantites.size %}
{% if inventory_total != expected_inventory_total %}
{% assign product_out_of_sync = hash %}
{% assign product_out_of_sync["product_id"] = product_id %}
{% assign product_out_of_sync["expected_inventory_total"] = expected_inventory_total %}
{% assign product_out_of_sync["current_inventory_total"] = inventory_total %}
{% assign product_out_of_sync["available_quantites"] = available_quantites %}
{% assign products_out_of_sync = products_out_of_sync | push: product_out_of_sync %}
{% else %}
{% assign cache_key = "inventory_by_product:" | append: product_id %}
{% action "cache", "set", cache_key, available_quantites.first %}
{% endif %}
{% endfor %}
{% if products_out_of_sync != blank %}
{% action "echo"
__error: "Variant inventory levels are not in sync for these products. Manually ensure everything is at the same level so they may be managed by this task.",
products_out_of_sync: products_out_of_sync
%}
{% endif %}
{% elsif event.topic contains "mechanic/scheduler/" %}
{% assign inventory_adjustments = array %}
{% assign products_missing_cache = hash %}
{% for pair in variants_by_product %}
{% assign product_id = pair[0] %}
{% assign variants = pair[1] %}
{% assign cache_key = "inventory_by_product:" | append: product_id %}
{% assign inventory_old = cache[cache_key] %}
{% if event.preview %}
{% assign inventory_old = 30 %}
{% endif %}
{% if inventory_old == blank %}
{% comment %}
-- if no cache has been set for this product yet, then save it for later processing and move to next product
{% endcomment %}
{% assign products_missing_cache[product_id] = variants %}
{% continue %}
{% endif %}
{% assign available_quantites = array %}
{% for variant in variants %}
{% assign available_quantites = available_quantites | push: variant.inventoryItem.inventoryLevel.quantities.first.quantity %}
{% endfor %}
{% assign inventory_total_old = inventory_old | times: available_quantites.size %}
{% assign inventory_total_new = available_quantites | sum %}
{% assign inventory_total_diff = inventory_total_new | minus: inventory_total_old %}
{% assign inventory_new = inventory_old | plus: inventory_total_diff %}
{% if inventory_new == inventory_old %}
{% log
message: "No inventory adjustments needed for this product.",
product_id: product_id
%}
{% continue %}
{% endif %}
{% log
message: "Adjusting inventory for this product.",
inventory_old: inventory_old,
inventory_total_old: inventory_total_old,
inventory_total_new: inventory_total_new,
inventory_total_diff: inventory_total_diff,
inventory_new: inventory_new,
product_id: product_id,
variants_count: variants.size
%}
{% action "cache", "set", cache_key, inventory_new %}
{% for variant in variants %}
{% assign inventory_adjustment = hash %}
{% assign inventory_adjustment["inventoryItemId"] = variant.inventoryItem.id %}
{% assign inventory_adjustment["locationId"] = primary_location.admin_graphql_api_id %}
{% assign inventory_adjustment["delta"] = inventory_new | minus: variant.inventoryItem.inventoryLevel.quantities.first.quantity %}
{% assign inventory_adjustments = inventory_adjustments | push: inventory_adjustment %}
{% endfor %}
{% endfor %}
{% if inventory_adjustments != blank %}
{% assign groups_of_inventory_adjustments = inventory_adjustments | in_groups_of: 250, fill_with: false %}
{% for group_of_inventory_adjustments in groups_of_inventory_adjustments %}
{% action "shopify" %}
mutation {
inventoryAdjustQuantities(
input: {
reason: "correction"
name: "available"
changes: {{ group_of_inventory_adjustments | graphql_arguments }}
}
) {
inventoryAdjustmentGroup {
reason
changes {
name
delta
quantityAfterChange
item {
id
sku
}
location {
name
}
}
}
userErrors {
code
field
message
}
}
}
{% endaction %}
{% endfor %}
{% endif %}
{% if products_missing_cache != blank %}
{% assign product_ids = products_missing_cache | keys %}
{% log
message: "Found these products without cache entries. Sending them to custom event to set caches if possible.",
product_ids: product_ids
%}
{% action "event" %}
{
"topic": "user/sync_variant_inventory/set_cache",
"task_id": {{ task.id | json }},
"data": {
"products_missing_cache": {{ products_missing_cache | json }}
}
}
{% endaction %}
{% endif %}
{% endif %}