# IStreamIdMapper.GetGrainKeyId(GrainBindings, StreamId)

[Type overview](/orleans/docs/api/csharp/microsoft.orleans.streaming/orleans.streams.istreamidmapper/) | [Methods](/orleans/docs/api/csharp/microsoft.orleans.streaming/orleans.streams.istreamidmapper/methods/)

```csharp
public abstract IdSpan GetGrainKeyId(GrainBindings grainBindings, StreamId streamId)
```

Gets the [GrainId](/orleans/docs/api/csharp/microsoft.orleans.core.abstractions/orleans.runtime.grainid/) which maps to the provided [StreamId](/orleans/docs/api/csharp/microsoft.orleans.streaming/orleans.runtime.streamid/)

### Parameters

- `grainBindings` (`GrainBindings`): The grain bindings.
- `streamId` (`StreamId`): The stream identifier.

### Returns

The [GrainId](/orleans/docs/api/csharp/microsoft.orleans.core.abstractions/orleans.runtime.grainid/) component.