Azure Cosmos DB
Dapr doesn’t transform state values while saving and retrieving states. Dapr requires all state store implementations to abide by a certain key format scheme (see the state management spec. You can directly interact with the underlying store to manipulate the state data, such as:
- Querying states.
- Creating aggregated views.
- Making backups.
NoteAzure Cosmos DB is a multi-modal database that supports multiple APIs. The default Dapr Cosmos DB state store implementation uses the Azure Cosmos DB SQL API.
Connect to Azure Cosmos DB
To connect to your Cosmos DB instance, you can either:
NoteWhen you configure an Azure Cosmos DB for Dapr, specify the exact database and collection to use. The following Cosmos DB SQL API samples assume you’ve already connected to the right database and a collection named “states”.
List keys by App ID
To get all state keys associated with application “myapp”, use the query:
SELECT * FROM states WHERE CONTAINS(states.id, 'myapp||')
The above query returns all documents with an id containing “myapp-”, which is the prefix of the state keys.
Get specific state data
To get the state data by a key “balance” for the application “myapp”, use the query:
SELECT * FROM states WHERE states.id = 'myapp||balance'
Read the value field of the returned document. To get the state version/ETag, use the command:
SELECT states._etag FROM states WHERE states.id = 'myapp||balance'
Read actor state
To get all the state keys associated with an actor with the instance ID “leroy” of actor type “cat” belonging to the application with ID “mypets”, use the command:
SELECT * FROM states WHERE CONTAINS(states.id, 'mypets||cat||leroy||')
And to get a specific actor state such as “food”, use the command:
SELECT * FROM states WHERE states.id = 'mypets||cat||leroy||food'
WarningYou should not manually update or delete states in the store. All writes and delete operations should be done via the Dapr runtime. The only exception: it is often required to delete actor records in a state store, once you know that these are no longer in use, to prevent a build up of unused actor instances that may never be loaded again.
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