---
title: Publishers.MapKeyPath
framework: combine
role: symbol
role_heading: Structure
path: combine/publishers/mapkeypath
---

# Publishers.MapKeyPath

A publisher that publishes the value of a key path.

## Declaration

```swift
struct MapKeyPath<Upstream, Output> where Upstream : Publisher
```

## Topics

### Declaring supporting types

- [Publishers.Output](combine/publishers/output.md)
- [Publishers.MapKeyPath.Failure](combine/publishers/mapkeypath/failure.md)

### Inspecting publisher properties

- [upstream](combine/publishers/mapkeypath/upstream.md)
- [keyPath](combine/publishers/mapkeypath/keypath.md)

## Relationships

### Conforms To

- [Publisher](combine/publisher.md)

## See Also

### Identifying properties with key paths

- [Publishers.MapKeyPath2](combine/publishers/mapkeypath2.md)
- [Publishers.MapKeyPath3](combine/publishers/mapkeypath3.md)