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docs: updates docs on unique index for fields #15969

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22 changes: 22 additions & 0 deletions docs/database/indexes.mdx
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Expand Up @@ -64,6 +64,28 @@ export const MyCollection: CollectionConfig = {
}
```

## Unique Fields

Setting `unique: true` on a field creates a **collection-wide** database unique index on that field's path. This means no two documents in the collection can share the same value for that field.

<Banner type="warning">
**Using `unique` on fields nested inside `array` or `blocks`** creates a
collection-wide unique index on the dotted path (e.g. `items.key`). This is
**not** the same as enforcing uniqueness within a single document's array rows
— it prevents *any two documents* from having the same value at that path.

Additionally, on **MongoDB**, documents that do not contain the array will all
share a `null` value at that path. Because unique indexes treat multiple
`null` values as duplicates, saving a second document without the array will
fail with a validation error.

If you need to enforce uniqueness _within_ a document's array rows (e.g. no
duplicate keys in the same document), use a custom
[`validate`](/docs/fields/overview#validation) function on the array field
instead.

</Banner>

## Localized fields and MongoDB indexes

When you set `index: true` or `unique: true` on a localized field, MongoDB creates one index **per locale path** (e.g., `slug.en`, `slug.da-dk`, etc.). With many locales and indexed fields, this can quickly approach MongoDB's per-collection index limit.
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52 changes: 31 additions & 21 deletions docs/fields/array.mdx
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Expand Up @@ -39,31 +39,41 @@ export const MyArrayField: Field = {

## Config Options

| Option | Description |
| ---------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **`name`** \* | To be used as the property name when stored and retrieved from the database. [More details](/docs/fields/overview#field-names). |
| **`label`** | Text used as the heading in the [Admin Panel](../admin/overview) or an object with keys for each language. Auto-generated from name if not defined. |
| **`fields`** \* | Array of field types to correspond to each row of the Array. |
| **`validate`** | Provide a custom validation function that will be executed on both the [Admin Panel](../admin/overview) and the backend. [More details](/docs/fields/overview#validation). |
| **`minRows`** | A number for the fewest allowed items during validation when a value is present. |
| **`maxRows`** | A number for the most allowed items during validation when a value is present. |
| **`saveToJWT`** | If this field is top-level and nested in a config supporting [Authentication](/docs/authentication/overview), include its data in the user JWT. |
| **`hooks`** | Provide Field Hooks to control logic for this field. [More details](../hooks/fields). |
| **`access`** | Provide Field Access Control to denote what users can see and do with this field's data. [More details](../access-control/fields). |
| **`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 an array of row data to be used for this field's default value. [More details](/docs/fields/overview#default-values). |
| **`localized`** | Enable localization for this field. Requires [localization to be enabled](/docs/configuration/localization) in the Base config. If enabled, a separate, localized set of all data within this Array will be kept, so there is no need to specify each nested field as `localized`. |
| **`required`** | Require this field to have a value. |
| **`labels`** | Customize the row labels appearing in the Admin dashboard. |
| **`admin`** | Admin-specific configuration. [More details](#admin-options). |
| **`custom`** | Extension point for adding custom data (e.g. for plugins) |
| **`interfaceName`** | Create a top level, reusable [Typescript interface](/docs/typescript/generating-types#custom-field-interfaces) & [GraphQL type](/docs/graphql/graphql-schema#custom-field-schemas). |
| **`dbName`** | Custom table name for the field when using SQL Database Adapter ([Postgres](/docs/database/postgres)). Auto-generated from name if not defined. |
| **`typescriptSchema`** | Override field type generation with providing a JSON schema |
| Option | Description |
| ---------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **`name`** \* | To be used as the property name when stored and retrieved from the database. [More details](/docs/fields/overview#field-names). |
| **`label`** | Text used as the heading in the [Admin Panel](../admin/overview) or an object with keys for each language. Auto-generated from name if not defined. |
| **`fields`** \* | Array of field types to correspond to each row of the Array. |
| **`validate`** | Provide a custom validation function that will be executed on both the [Admin Panel](../admin/overview) and the backend. [More details](/docs/fields/overview#validation). |
| **`minRows`** | A number for the fewest allowed items during validation when a value is present. |
| **`maxRows`** | A number for the most allowed items during validation when a value is present. |
| **`saveToJWT`** | If this field is top-level and nested in a config supporting [Authentication](/docs/authentication/overview), include its data in the user JWT. |
| **`hooks`** | Provide Field Hooks to control logic for this field. [More details](../hooks/fields). |
| **`access`** | Provide Field Access Control to denote what users can see and do with this field's data. [More details](../access-control/fields). |
| **`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 an array of row data to be used for this field's default value. [More details](/docs/fields/overview#default-values). |
| **`localized`** | Enable localization for this field. Requires [localization to be enabled](/docs/configuration/localization) in the Base config. If enabled, a separate, localized set of all data within this Array will be kept, so there is no need to specify each nested field as `localized`. |
| **`required`** | Require this field to have a value. |
| **`labels`** | Customize the row labels appearing in the Admin dashboard. |
| **`admin`** | Admin-specific configuration. [More details](#admin-options). |
| **`custom`** | Extension point for adding custom data (e.g. for plugins) |
| **`interfaceName`** | Create a top level, reusable [Typescript interface](/docs/typescript/generating-types#custom-field-interfaces) & [GraphQL type](/docs/graphql/graphql-schema#custom-field-schemas). |
| **`dbName`** | Custom table name for the field when using SQL Database Adapter ([Postgres](/docs/database/postgres)). Auto-generated from name if not defined. |
| **`typescriptSchema`** | Override field type generation with providing a JSON schema |
| **`virtual`** | Provide `true` to disable field in the database, or provide a string path to [link the field with a relationship](/docs/fields/overview#string-path-virtual-fields). See [Virtual Fields](https://payloadcms.com/blog/learn-how-virtual-fields-can-help-solve-common-cms-challenges) |

_\* An asterisk denotes that a property is required._

<Banner type="warning">
Setting `unique: true` on a field **inside** an Array creates a
collection-wide database unique index — not a per-document one. No two
documents in the collection can share the same value at that nested path, and
on MongoDB, documents without the array will collide on `null`. To enforce
uniqueness within a single document's rows, use a custom
[`validate`](/docs/fields/overview#validation) function on this Array field.
[More details](/docs/database/indexes#unique-fields).
</Banner>

## Admin Options

To customize the appearance and behavior of the Array Field in the [Admin Panel](../admin/overview), you can use the `admin` option:
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14 changes: 12 additions & 2 deletions docs/fields/blocks.mdx
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Expand Up @@ -56,7 +56,7 @@ This page is divided into two parts: first, the settings of the Blocks Field, an
| **`hidden`** | Restrict this field's visibility from all APIs entirely. Will still be saved to the database, but will not appear in any API response or the Admin Panel. |
| **`defaultValue`** | Provide an array of block data to be used for this field's default value. [More details](/docs/fields/overview#default-values). |
| **`localized`** | Enable localization for this field. Requires [localization to be enabled](/docs/configuration/localization) in the Base config. If enabled, a separate, localized set of all data within this field will be kept, so there is no need to specify each nested field as `localized`. |
| **`unique`** | Enforce that each entry in the Collection has a unique value for this field. |
| **`unique`** | Enforce that each entry in the Collection has a unique value for this field. This creates a database-level unique index on the field's path. [More details](/docs/database/indexes#unique-fields). |
| **`labels`** | Customize the block row labels appearing in the Admin dashboard. |
| **`admin`** | Admin-specific configuration. [More details](#admin-options). |
| **`custom`** | Extension point for adding custom data (e.g. for plugins) |
Expand All @@ -65,6 +65,16 @@ This page is divided into two parts: first, the settings of the Blocks Field, an

_\* An asterisk denotes that a property is required._

<Banner type="warning">
Setting `unique: true` on a field **inside** a Block creates a collection-wide
database unique index — not a per-document one. No two documents in the
collection can share the same value at that nested path, and on MongoDB,
documents without the block will collide on `null`. To enforce uniqueness
within a single document's blocks, use a custom
[`validate`](/docs/fields/overview#validation) function on this Blocks field.
[More details](/docs/database/indexes#unique-fields).
</Banner>

### Block Admin Options

To customize the appearance and behavior of the Blocks Field in the [Admin Panel](../admin/overview), you can use the `admin` option:
Expand Down Expand Up @@ -506,7 +516,7 @@ Blocks can be conditionally enabled using the `filterOptions` property on the bl
- `filterOptions` is re-evaluated as part of the form state request, whenever the document data changes.
- If a block is present in the field but no longer allowed by `filterOptions`, a validation error will occur when saving.

### Example
### filterOptions Example

```ts
{
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