[Home](./index.md) > [@firebase/firestore](./firestore.md) > [lite](./firestore_lite.md) > [WriteBatch](./firestore_lite.writebatch.md) > [set](./firestore_lite.writebatch.set_1.md) ## WriteBatch.set() method Writes to the document referred to by the provided [DocumentReference](./firestore_.documentreference.md). If the document does not exist yet, it will be created. If you provide `merge` or `mergeFields`, the provided data can be merged into an existing document. Signature: ```typescript set(documentRef: DocumentReference, data: Partial, options: SetOptions): WriteBatch; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | documentRef | [DocumentReference](./firestore_lite.documentreference.md)<T> | A reference to the document to be set. | | data | Partial<T> | An object of the fields and values for the document. | | options | [SetOptions](./firestore_lite.setoptions.md) | An object to configure the set behavior. | Returns: [WriteBatch](./firestore_lite.writebatch.md) This `WriteBatch` instance. Used for chaining method calls.