---
lang: en
title: 'API docs: repository.createhasonerepositoryfactory'
keywords: LoopBack 4.0, LoopBack 4
sidebar: lb4_sidebar
editurl: https://github.com/strongloop/loopback-next/tree/master/packages/repository
permalink: /doc/en/lb4/apidocs.repository.createhasonerepositoryfactory.html
---

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[Home](./index.md) &gt; [@loopback/repository](./repository.md) &gt; [createHasOneRepositoryFactory](./repository.createhasonerepositoryfactory.md)

## createHasOneRepositoryFactory() function

Enforces a constraint on a repository based on a relationship contract between models. For example, if a Customer model is related to an Address model via a HasOne relation, then, the relational repository returned by the factory function would be constrained by a Customer model instance's id(s).

<b>Signature:</b>

```typescript
export declare function createHasOneRepositoryFactory<Target extends Entity, TargetID, ForeignKeyType>(relationMetadata: HasOneDefinition, targetRepositoryGetter: Getter<EntityCrudRepository<Target, TargetID>>): HasOneRepositoryFactory<Target, ForeignKeyType>;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  relationMetadata | <code>HasOneDefinition</code> | The relation metadata used to describe the relationship and determine how to apply the constraint. |
|  targetRepositoryGetter | <code>Getter&lt;EntityCrudRepository&lt;Target, TargetID&gt;&gt;</code> | The repository which represents the target model of a relation attached to a datasource. |

<b>Returns:</b>

`HasOneRepositoryFactory<Target, ForeignKeyType>`

The factory function which accepts a foreign key value to constrain the given target repository