feathers/docs/api/schema/index.md
2022-10-17 12:49:03 -07:00

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outline: deep
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# Schema Overview
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`@feathersjs/schema` provides a way to define data models and to dynamically resolve them. It comes in two main parts:
- [Schema](./schema.md) - Uses [JSON schema](https://json-schema.org/) to define a data model with TypeScript types and basic validations. This allows us to:
- Ensure data is valid and always in the right format
- Automatically get TypeScript types from schema definitions
- Automatically generate API documentation
- Create [database adapter](../databases/common.md) models without duplicating the data format
- Validate query string queries and convert them to the right type
- [Resolvers](./resolvers.md) - Resolve schema properties based on a context (usually the [hook context](../hooks.md)). This can be used for many different things like:
- Populating associations
- Securing queries and e.g. limiting requests to a user
- Removing protected properties for external requests
- Ability to add read- and write permissions on the property level
- Hashing passwords and validating dynamic password policies
Here is an example of a user schema definition and resolver:
```ts
import { HookContext } from './definitions';
import { schema, resolve, type Infer } from '@feathersjs/schema';
export const userSchema = schema({
$id: 'User',
type: 'object',
additionalProperties: false,
required: ['email', 'password'],
properties: {
id: { type: 'number' },
email: { type: 'string' },
password: { type: 'string' }
}
} as const);
export type User = Infer<typeof userSchema>;
export const userDataResolver = resolve<User, HookContext>({
properties: {
password: async (value) => {
// Return a hashed version of the password before storing it in the database
return bcrypt(value);
}
}
});
export const userResultResolver = resolve<User, HookContext>({
properties: {
password: async (value, _user, context) => {
// Do not return the password for external requests
if (context.params.provider) {
return undefined;
}
return value;
}
}
});
```