Tutorial/cascade delete #70
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| --- | ||
| title: "Cascading Delete" | ||
| description: "In this tutorial we will show you how to perform a cascading delete on the client." | ||
| keywords: ["data", "cascade", "delete"] | ||
| --- | ||
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| # Introduction | ||
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| Since PowerSync utilizes SQLite views instead of standard tables, SQLite features like constraints, foreign keys, or cascading deletes are not available. | ||
| Currently, there is no direct support for cascading deletes on the client. However, you can achieve this by either: | ||
| 1. Manually deleting all the relevant tables within a **single transaction**, OR | ||
| <Note> | ||
| Every local mutation performed against SQLite via the PowerSync SDK will be returned in `uploadData`. So as long as you are using `.execute()` for the mutation, | ||
| the operation will be present in the upload queue. | ||
| </Note> | ||
| 2. Implementing triggers (which is more complex) | ||
| <Note> | ||
| You create triggers on the internal tables (not the views defined by the client schema), similar to what is | ||
| done [here](https://github.com/powersync-ja/powersync-js/blob/e77b1abfbed91988de1f4c707c24855cd66b2219/demos/react-supabase-todolist/src/app/utils/fts_setup.ts#L50) | ||
| </Note> | ||
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| # Example | ||
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| The following example is taken from the [React Native To-Do List example app](https://github.com/powersync-ja/powersync-js/tree/main/demos/react-native-supabase-todolist). | ||
| It showcases how to delete a `list` and all its associated `todos` in a single transaction. | ||
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| ```typescript | ||
| const deleteList = async (id: string) => { | ||
| await system.powersync.writeTransaction(async (tx) => { | ||
| // Delete associated todos | ||
| await tx.execute(`DELETE FROM ${TODO_TABLE} WHERE list_id = ?`, [id]); | ||
| // Delete list record | ||
| await tx.execute(`DELETE FROM ${LIST_TABLE} WHERE id = ?`, [id]); | ||
| }); | ||
| }; | ||
| ``` | ||
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| <Note> | ||
| An important thing to note is that the local SQLite database will always match the online database, as long as the tables are in the publication, when online. | ||
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| For example, if you delete a record from the `lists` table and Supabase cascade deletes a record from the `todo` table, PowerSync will also delete the `todo` record when online. | ||
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| </Note> | ||
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| --- | ||
| title: "Overview" | ||
| description: "A collection of tutorials showcasing various data management strategies and use cases." | ||
| --- | ||
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| <CardGroup> | ||
| <Card title="Cascading Delete" icon="database" href="/tutorials/client/data/cascading-delete" horizontal/> | ||
| </CardGroup> |
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Maybe worth linking to https://docs.powersync.com/architecture/client-architecture#schema so they can get more details about the internal tables vs views thing