[Home](./index.md) > [@firebase/firestore](./firestore.md) > [lite](./firestore_lite.md) > [FirestoreDataConverter](./firestore_lite.firestoredataconverter.md) > [toFirestore](./firestore_lite.firestoredataconverter.tofirestore.md) ## FirestoreDataConverter.toFirestore() method Called by the Firestore SDK to convert a custom model object of type `T` into a plain Javascript object (suitable for writing directly to the Firestore database). Used with , and . Signature: ```typescript toFirestore(modelObject: T): DocumentData; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | modelObject | T | | Returns: [DocumentData](./firestore_lite.documentdata.md)