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https://github.com/alveflo/tsmediator
Tiny flexible mediator implemented in TypeScript
https://github.com/alveflo/tsmediator
mediator typescript
Last synced: 14 days ago
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Tiny flexible mediator implemented in TypeScript
- Host: GitHub
- URL: https://github.com/alveflo/tsmediator
- Owner: alveflo
- License: mit
- Created: 2017-03-19T14:25:44.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2023-10-16T16:14:44.000Z (about 1 year ago)
- Last Synced: 2024-12-14T22:33:22.305Z (19 days ago)
- Topics: mediator, typescript
- Language: TypeScript
- Size: 383 KB
- Stars: 25
- Watchers: 3
- Forks: 4
- Open Issues: 8
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# TS Mediator
Tiny flexible mediator implemented in TypeScript
# Installation
## Production
```
$ npm install --save tsmediator
```
## Development
```
$ git clone https://github.com/alveflo/tsmediator.git
$ cd tsmediator
$ npm install && npm test
```
# Usage
## Setup
No setup is required per se, other than registering handlers for specific messages (commands/queries). However, this implemented relies on ES7 decorators and therefore `experimentalDecorators` needs to be set to `true` in your `tsconfig.json` file.
## API
`Mediator`
- `Mediator.Send(type: string, payload: T)` where `type` is the registered message type and payload is the data sent, where `T` is the datatype that the handler is expected to process.
## Registering handlers
Registering a handler is easy, simple add the decorator `Handler(message)` onto your class, and implement the `ICommandHandler` interface and you're ready to roll. Note that this automatic registration only works if you, somewhere in your code, is referring to the handlers type (e.g. `CmdHandler.Type` as shown below).
If you're not explicitly referring to the handlers type, the decorator will not be run automatically and the handler will not be registered. In this case you might want to register the handler manually. In that case, simply use
```TypeScript
import { Container } from 'tsmediator';
Container.RegisterHandler(YourHandler);
```
### Command handler example
```TypeScript
import { ICommandHandler, Handler } from 'tsmediator';
@Handler(CmdHandler.Type)
class CmdHandler implements ICommandHandler {
public static get Type():string { return "foo"; }
Log() {}
Validate(payload: string) {
if (payload !== 'foo bar') {
throw Error('Some error');
}
}
Handle(payload: string) {
return 5 * 5;
}
}
```
## Send example
The following example shows how you would send a command into the registered handlers above.
```TypeScript
import { Mediator } from 'tsmediator';
let mediator: Mediator = new Mediator();
mediator.Send(CmdHandler.Type, 5);
```
## Middlewares
The mediator also supports adding middleware to the mediator. This is used if you have any generic actions that you would like to be triggered every time a the mediator is used. What you need to do is create a class that implements `IMediatorMiddleware` and register the middleware with the mediator.
### Execution order
The order that you register the middlewares will also be the order that they will be executed.
If you have registered two middlewares they will be executed in this order: Middleware1 -> Middleware2 -> Handler -> Middleware2 -> Middleware1
### Example
As an example we can easily create a logging middleware:
```TypeScript
class LoggingMiddleware implements IMediatorMiddleware {
private logger: ILogger;
constructor() {
this.logger = new Logger();
}
public PreProcess(payload: any): void {
logger.Log(`Processing object ${JSON.stringify(payload)}`)
}
public PostProcess(payload: any, response: any): void {
logger.Log(`Was: ${JSON.stringify(payload)}, now is: ${JSON.stringify(response)}`);
}
}
```
To register the middleware, you do this:
```TypeScript
let loggingMiddleware = new LoggingMiddleware();
mediator.Use(loggingMiddleware);
```
## Overriding mediator behaviour
You can easily override the default mediator behaviour by extending the `BaseMediator`. The only thing you need to do is to resolve the registered handler class by calling `BaseMediator.Resolve(message)`. The message to handler connections are handled under the hood, so you don't need to worry about that at all.
```TypeScript
import { BaseMediator } from "./baseMediator";
export class MyCustomMediator extends BaseMediator {
public Send(command: string, payload: any) {
return this.Process(command, payload);
}
public Request(query: string, payload: any) {
return this.Process(query, payload);
}
private Process(msg: string, payload: any) {
let handler: any = super.Resolve(msg);
try {
handler.Validate(payload);
} catch (ex) {
throw ex;
}
handler.Log();
return handler.Handle(payload);
}
}
```
# Licence
MIT License
Copyright (c) 2017- Victor Alveflo
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.