To add Product documents to an Order document
To allow for an Order to feature a placedBy relationship to either an Organization or User collection
To assign Category documents to Post documents

Config

Option	Description
`name` *	To be used as the property name when stored and retrieved from the database. More
`relationTo` *	Provide one or many collection `slug`s to be able to assign relationships to.
`filterOptions`	A query to filter which options appear in the UI and validate against. More.
`hasMany`	Boolean when, if set to `true`, allows this field to have many relations instead of only one.
`minRows`	A number for the fewest allowed items during validation when a value is present. Used with `hasMany`.
`maxRows`	A number for the most allowed items during validation when a value is present. Used with `hasMany`.
`maxDepth`	Sets a number limit on iterations of related documents to populate when queried. Depth
`label`	Text used as a field label in the Admin panel or an object with keys for each language.
`unique`	Enforce that each entry in the Collection has a unique value for this field.
`validate`	Provide a custom validation function that will be executed on both the Admin panel and the backend. More
`index`	Build an index for this field to produce faster queries. Set this field to `true` if your users will perform queries on this field's data often.
`saveToJWT`	If this field is top-level and nested in a config supporting Authentication, include its data in the user JWT.
`hooks`	Provide field-based hooks to control logic for this field. More
`access`	Provide field-based access control to denote what users can see and do with this field's data. More
`hidden`	Restrict this field's visibility from all APIs entirely. Will still be saved to the database, but will not appear in any API or the Admin panel.
`defaultValue`	Provide data to be used for this field's default value. More
`localized`	Enable localization for this field. Requires localization to be enabled in the Base config.
`required`	Require this field to have a value.
`admin`	Admin-specific configuration. See the default field admin config for more details.
`custom`	Extension point for adding custom data (e.g. for plugins)

* An asterisk denotes that a property is required.

Admin config

In addition to the default field admin config, the Relationship field type also allows for the following admin-specific properties:

isSortable

Set to true if you'd like this field to be sortable within the Admin UI using drag and drop (only works when hasMany is set to true).

allowCreate

Set to false if you'd like to disable the ability to create new documents from within the relationship field (hides the "Add new" button in the admin UI).

sortOptions

The sortOptions property allows you to define a default sorting order for the options within a Relationship field's dropdown. This can be particularly useful for ensuring that the most relevant options are presented first to the user.

You can specify sortOptions in two ways:

As a string:

Provide a string to define a global default sort field for all relationship field dropdowns across different collections. You can prefix the field name with a minus symbol ("-") to sort in descending order.

Example:

1sortOptions: 'fieldName',

This configuration will sort all relationship field dropdowns by "fieldName" in ascending order.

As an object :

Specify an object where keys are collection slugs and values are strings representing the field names to sort by. This allows for different sorting fields for each collection's relationship dropdown.

Example:

1sortOptions: {
"pages"

"fieldName1",
  "posts"

"-fieldName2",
  "categories"

"fieldName3"
11}

In this configuration:

Dropdowns related to pages will be sorted by "fieldName1" in ascending order.
Dropdowns for posts will use "fieldName2" for sorting in descending order (noted by the "-" prefix).
Dropdowns associated with categories will sort based on "fieldName3" in ascending order.

Note: If sortOptions is not defined, the default sorting behavior of the Relationship field dropdown will be used.

Filtering relationship options

Options can be dynamically limited by supplying a query constraint, which will be used both for validating input and filtering available relationships in the UI.

The filterOptions property can either be a Where query, or a function returning true to not filter, false to prevent all, or a Where query. When using a function, it will be called with an argument object with the following properties:

Property	Description
`relationTo`	The `relationTo` to filter against (as defined on the field)
`data`	An object of the full collection or global document currently being edited
`siblingData`	An object of the document data limited to fields within the same parent to the field
`id`	The value of the collection `id`, will be `undefined` on create request
`user`	The currently authenticated user object

Example

1import { CollectionConfig } from 'payload/types'
2
3export const ExampleCollection: CollectionConfig = {
slug: 'example-collection',
fields: [
  {
    name: 'purchase',
    type: 'relationship',
    relationTo: ['products', 'services'],
    filterOptions: ({ relationTo, siblingData }) => {
      // returns a Where query dynamically by the type of relationship
      if (relationTo === 'products') {
        return {
          stock: { greater_than: siblingData.quantity },
        }
      }
17
      if (relationTo === 'services') {
        return {
          isAvailable: { equals: true },
        }
      }
    },
  },
],
26}

You can learn more about writing queries here.

How the data is saved

Given the variety of options possible within the relationship field type, the shape of the data needed for creating and updating these fields can vary. The following sections will describe the variety of data shapes that can arise from this field.

Has One

The most simple pattern of a relationship is to use hasMany: false with a relationTo that allows for only one type of collection.

1{
slug: 'example-collection',
  fields

[
  {
    name: 'owner', // required
    type: 'relationship', // required
    relationTo: 'users', // required
    hasMany: false,
  }
]
13}

The shape of the data to save for a document with the field configured this way would be:

1{
2  // ObjectID of the related user
3  "owner": "6031ac9e1289176380734024"
4}

When querying documents in this collection via REST API, you could query as follows:

?where[owner][equals]=6031ac9e1289176380734024.

Has One - Polymorphic

Also known as dynamic references, in this configuration, the relationTo field is an array of Collection slugs that tells Payload which Collections are valid to reference.

1{
slug: 'example-collection',
  fields

[
  {
    name: 'owner', // required
    type: 'relationship', // required
    relationTo: ['users', 'organizations'], // required
    hasMany: false,
  }
]
13}

The shape of the data to save for a document with more than one relationship type would be:

1{
2  "owner": {
3    "relationTo": "organizations",
4    "value": "6031ac9e1289176380734024"
5  }
6}

Here is an example for how to query documents by this data (note the difference in referencing the owner.value):

?where[owner.value][equals]=6031ac9e1289176380734024.

You can also query for documents where a field has a relationship to a specific Collection:

?where[owners.relationTo][equals]=organizations.

This query would return only documents that have an owner relationship to organizations.

Has Many

The hasMany tells Payload that there may be more than one collection saved to the field.

1{
slug: 'example-collection',
  fields

[
  {
    name: 'owners', // required
    type: 'relationship', // required
    relationTo: 'users', // required
    hasMany: true,
  }
]
13}

To save the to hasMany relationship field we need to send an array of IDs:

1{
2  "owners": [
3    "6031ac9e1289176380734024",
4    "602c3c327b811235943ee12b"
5  ]
6}

When querying documents, the format does not change for arrays:

?where[owners][equals]=6031ac9e1289176380734024.

Has Many - Polymorphic

1{
slug: 'example-collection',
  fields

[
  {
    name: 'owners', // required
    type: 'relationship', // required
    relationTo: ['users', 'organizations'], // required
    hasMany: true,
    required: true,
  }
]
14}

Relationship fields with hasMany set to more than one kind of collections save their data as an array of objects—each containing the Collection slug as the relationTo value, and the related document id for the value:

1{
"owners": [
  {
    "relationTo": "users",
    "value": "6031ac9e1289176380734024"
  },
  {
    "relationTo": "organizations",
    "value": "602c3c327b811235943ee12b"
  }
]
12}

Querying is done in the same way as the earlier Polymorphic example:

?where[owners.value][equals]=6031ac9e1289176380734024.

Querying and Filtering Polymorphic Relationships

Polymorphic and non-polymorphic relationships must be queried differently because of how the related data is stored and may be inconsistent across different collections. Because of this, filtering polymorphic relationship fields from the Collection List admin UI is limited to the id value.

For a polymorphic relationship, the response will always be an array of objects. Each object will contain the relationTo and value properties.

The data can be queried by the related document ID:

?where[field.value][equals]=6031ac9e1289176380734024.

Or by the related document Collection slug:

?where[field.relationTo][equals]=your-collection-slug.

However, you cannot query on any field values within the related document. Since we are referencing multiple collections, the field you are querying on may not exist and break the query.

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Relationship Field