> ## Documentation index
>
> Fetch the complete documentation index at: https://andesine.app/docs/llms.txt
> Use it to find all pages before you explore further.

# Schemas

> Give the entries of a collection the same properties and content areas.

A schema gives all entries in a collection the same structure. For example, a `Changelog` collection can give each entry a `Version` property, a `Release date`, and a `Summary` and `Content` area. The API and your sites then get the same fields from every entry.

![The schema editor with Description and Release date properties and Content fragment.](https://andesine.app/docs/_andesine/assets/9a57b010d5cd109a5ac15945c03dc5d49336b14dc31d6170526e44d9d54d2a1a.webp)

## Fields

A schema has two kinds of fields.

**Properties** hold one value:

| Type         | Value                                |
| ------------ | ------------------------------------ |
| Text         | A short text                         |
| Number       | A number                             |
| Checkbox     | On or off                            |
| Date         | A date                               |
| URL          | A link                               |
| Select       | One option from a list that you set  |
| Multi-select | Any options from a list that you set |

**Fragments** are named areas of rich content, such as `Summary` and `Content`. For each fragment, you can set:

- **Allowed blocks**: the blocks that writers can use in it, for example only paragraphs and lists. Paragraphs are always allowed.
- **Initial content**: content that new entries start with, such as a template with headings.

Each field is required unless you make it optional. Writers add optional fields to an entry from the slash menu, under **Optional fields**.

<Callout type="tip">
  All content of an entry must be inside a field. Give each schema at least one fragment, such as `Content`, for the body of the entry.
</Callout>

## Add or edit a schema

1. Open the menu of a collection and select **Add schema**, or **Edit schema** for a collection that has one.
2. Type `/` in the schema editor to add properties and fragments. Select a field to change its name, type, options, and settings.
3. Select **Save & apply**.

The schema editor is shared: other members who edit the same schema see your changes live. Entries do not change until you apply the schema.

## Apply a schema

When you apply a schema, Andesine converts all entries in the collection, and in the collections inside it, to the new structure. This is a schema migration. The explorer shows its progress: **Migration queued**, **Applying schema**, and then **Schema applied**. During the migration, you cannot change the entries of the collection.

Check the changes before you apply them:

- Renaming a field keeps its content.
- Removing a field removes its content from the entries.
- Changing the type of a property can remove values that do not fit the new type.
- Content that is not inside a field is removed.

Andesine saves a version of each entry before it converts the entry, so you can get removed content back from the entry's [versions](https://andesine.app/docs/organizing-content/versions/). If a migration fails, Andesine restores the converted entries and shows **Schema migration failed**.

You must be online to apply a schema.

## Inheritance

Collections inside a collection with a schema inherit its fields. Inherited fields show **Inherited from parent schema**. You cannot change inherited fields in a child collection, but you can add a schema to the child collection to add more fields.

When you remove a schema, the collection keeps the fields that it inherits from its parent collections.

## Schema versions

Andesine saves a version of the schema each time you apply it. In the versions of a schema, you can rename a version, or select **Revert & apply** to apply an earlier version again.

## Schemas in the API

The API returns each property by a key made from its name, for example `releaseDate` for **Release date**. Fragments return their content as a JSON document, or as MDX. To get TypeScript types for your schemas, see [Content types](https://andesine.app/docs/developers/content-types/).