Connect entities with relationships

In the Anythink dashboard

1. Go to Settings › Data Model and select the entity that holds the link, such as orders.
2. Select Add Field. The Create New Field drawer opens.
3. Pick Many-to-One, or one of the other relationship types.
4. Under Related Entity, choose the entity to link to, such as customers.
5. Choose On Deletion (see What happens on delete).
6. Enter a Name, such as customer.
7. For One-to-Many only, choose a Foreign Key. It lists the many-to-one fields on the related entity. Choose + Create New Target Field to have Anythink create that many-to-one field, then give it a New Target Field Name.
8. Select Create Field.

Every control on the form, in order:

The related entity can't be changed afterwards, and neither can the field's name or type. To link to a different entity, add a new field.

With the CLI

anythink fields add orders customer --type many-to-one --target customers --on-delete "SET NULL"
anythink fields add profiles customer --type one-to-one --target customers
anythink fields add posts tags --type many-to-many --target tags

Other fields add flags work on relationship fields too: --label, --description, --default, --required, --unique, --indexed, --searchable, --public (publicly searchable) and --name-field. Run anythink fields add --help for the full list.

--target is the related entity's name, and --on-delete takes CASCADE (the default), SET NULL, SET DEFAULT or RESTRICT. Add --required to demand a value. A required field can't use SET NULL.

The CLI's fields add creates many-to-one, one-to-one and many-to-many fields. For the one-to-many side, add the many-to-one field on the child entity as above, then create the one-to-many field in the Anythink dashboard, or send the field to the API yourself. You need the related entity's ID (anythink entities get orders shows it) and the name of the many-to-one field it points back through:

anythink fetch /entities/customers/fields --method POST --body '{
  "name": "orders",
  "database_type": "one-to-many",
  "display_type": "relationship",
  "relationship": {
    "target_entity_id": 654,
    "target_field_name": "customer",
    "on_deletion": "CASCADE"
  }
}'

Check the result with anythink fields get customers orders.

With an AI assistant (MCP)

Link orders to customers: each order has one customer. If the customer is deleted, keep the order and clear the link.

The assistant uses the cli tool to run fields add orders customer --type many-to-one --target customers --on-delete "SET NULL". Ask for the reverse side too ("and let a customer show its orders") and it adds the one-to-many field through the API.

In the Anythink dashboard

1. Open the entity from the sidebar. Select the Add button, named after the entity (such as Add Order), to create a record.
2. For a many-to-one or one-to-one field, pick the related record from the list.
3. For a one-to-many or many-to-many field, select Add Existing to pick records, or Create New to make a new related record and link it.
4. Save the record.

The user needs orders:create to add records. See Roles and permissions.

With the CLI

Set the link when you create the record:

anythink data create orders --data '{"reference": "A-3", "total": 30, "customer": 1}'
anythink data create posts --data '{"title": "Hello", "tags": [1, 4]}'

A link to an id that doesn't exist is refused with 400, and a record that's locked can't be changed. The same body works over the REST API:

POST /org/{project_id}/entities/orders/items
Content-Type: application/json

{ "reference": "A-3", "total": 30, "customer": 1 }

See REST API reference for the record endpoints.

With an AI assistant (MCP)

Create an order A-3 for 30 pounds for customer 1, and tag post 7 with tags 1, 4 and 9.

The assistant uses the cli tool to run data create and data update with the ids. To find an id first, ask it to look the customer up by name.

In the Anythink dashboard

The record grid shows a related record by its name, and a count such as 3 items for one-to-many and many-to-many fields. Open a record to see the related records in full, and select one to open its details in a panel. The Select Fields picker above the grid lists the fields of related entities as paths such as customer.name, so you can add them as columns. See Records, views and CSV import.

With the CLI

anythink data get orders 3
anythink fetch "/entities/orders/items?fields=reference,total,customer.name&pageSize=5"
anythink fetch "/entities/customers/items/1?fields=name,orders.reference"

data get returns the record with its default expansion. Use fetch when you need fields.

With an AI assistant (MCP)

Show me order A-3 with its customer's name and email, and list the orders for customer 1.

The assistant uses the cli tool to call the records endpoint with fields and shows you the related records it gets back.

In the Anythink dashboard

Filtering across a relationship is a query on the records API, so use the CLI or REST API shown below. In the grid, add the related field as a column with Select Fields to see it beside each record.

With the CLI

anythink data list orders --filter 'customer.name=C:lovelace&status=paid'
anythink data list customers --filter '{"orders.status": "paid"}'

With an AI assistant (MCP)

Which orders belong to customers whose name contains Lovelace?

The assistant runs data list orders with a customer.name filter and shows the matching orders.

A path that names a field the entity doesn't have is ignored, so a misspelt path returns unfiltered records. Check the total if a result looks too big.

In the Anythink dashboard

1. In Settings › Data Model, create customers with a required, unique Small text field email and a Small text field name, marked as the name field.
2. Create orders with a Small text field reference (name field) and a Decimal field total.
3. On orders, add a Many-to-One field named customer. Choose customers as the Related Entity and Set Null for On Deletion.
4. On customers, add a One-to-Many field named orders. Choose orders as the Related Entity and customer as the Foreign Key. Set On Deletion to Set Null.
5. Open customers in the sidebar, add Ada Lovelace, then open orders and add an order with customer set to her.

With the CLI

anythink entities create customers
anythink fields add customers name --type varchar --required --name-field
anythink fields add customers email --type varchar --required --unique

anythink entities create orders
anythink fields add orders reference --type varchar --name-field
anythink fields add orders total --type decimal
anythink fields add orders customer --type many-to-one --target customers --on-delete "SET NULL"

anythink data create customers --data '{"name": "Ada Lovelace", "email": "ada@example.com"}'
anythink data create orders --data '{"reference": "A-3", "total": 30, "customer": 1}'

Add the reverse orders field on customers with the one-to-many request shown earlier, setting target_entity_id to the ID of orders and target_field_name to customer. Then read both directions:

anythink fetch "/entities/orders/items?fields=reference,customer.name"
anythink fetch "/entities/customers/items/1?fields=name,orders.reference,orders.total"
anythink data list orders --filter 'customer.name=C:lovelace'

With an AI assistant (MCP)

Set up customers and orders. A customer has a name and a unique email. An order has a reference and a total. Each order belongs to one customer, and a customer shows their orders. If a customer is deleted, keep their orders and clear the link. Then add Ada Lovelace with one order for 30 pounds, and show me the order with its customer.

The assistant creates both entities and their fields with the cli tool, adds the links, creates the two records and reads the order back with its customer expanded.

Before your app's users can read any of this, grant their role orders:read and customers:read. A user who can read orders but not customers sees the order without the customer's details.