# mr-use-case
> A perfect way to wrap your business logic fast and properly.
Latest version **0.8.1** (published 2022-01-06) · ISC license · 0 weekly downloads
## Install
```sh
npm install mr-use-case
pnpm add mr-use-case
yarn add mr-use-case
bun add mr-use-case
```
## Health
**Score 25/100 (F)** — status: abandoned.
Positive: has types; no vulnerabilities; high quality score.
Warnings: low downloads; no esm support; pre 1.0.
Negative: abandoned; low maintenance score.
## Facts
| | |
|---|---|
| Version | 0.8.1 |
| Published | 2022-01-06 |
| First published | 2021-01-31 |
| Weekly downloads | 0 |
| License | ISC |
| TypeScript types | bundled |
| Module format | CommonJS |
| Dependencies | 1 |
| Unpacked size | 11.4 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 0 |
| Author | Ilia Donskikh |
| Maintainers | donivnpm |
| Keywords | usecase, typescript |
## Links
- npm: https://www.npmjs.com/package/mr-use-case
- Repository: https://github.com/IlyaDonskikh/mr-use-case
- Homepage: https://github.com/IlyaDonskikh/mr-use-case#readme
- Issues: https://github.com/IlyaDonskikh/mr-use-case/issues
- npm.io page: https://npm.io/package/mr-use-case
## Dependencies (1)
- [mr-error](https://npm.io/package/mr-error.md) ^0.7.2
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## Recent versions
- 0.8.1 (latest) — 2022-01-06
- 0.8.0 — 2021-05-25
- 0.7.0 — 2021-05-18
- 0.6.3 — 2021-05-16
- 0.6.2 — 2021-04-03
- 0.6.1 — 2021-01-31
- 0.6.0 — 2021-01-31
- 0.5.0 — 2021-01-31
## README
# Mr.UseCase
The perfect way to wrap your business logic fast and properly.
## Introduction
> These use cases orchestrate the flow of data to and from the entities, and direct those entities to use their Critical Business Rules to achieve the goals of the use case.
[📖 Clean Architecture book](http://www.plainionist.net/Clean-Architecture/)
The UseCase layer allows you to achieve significant benefits in the following parts of writing code:
- Make development process clear for all participants
- Speed up the development of production-ready projects
- Avoid complexity
- Reduce coupling
So, developers and use cases have to be friends🤝 forever at least for reasons outlined above.
## Installation
Just one step.
```shell
npm i mr-use-case
```
And use it where you need it.
```typescript
import { MrUseCase } from 'mr-use-case';
```
#### Localization
As well you have an option to localize errors through error builder customization:
```typescript
import { MrUseCase } from 'mr-use-case';
import { ErrorsBuilder } from './errors.builder';
export function UseCase() {
return MrUseCase({ errorsBuilder: ErrorsBuilder });
}
```
Read more about it on [🥞 Mr.Error page](https://github.com/IlyaDonskikh/mr-error).
## Overview
This section contains a simple use case that shows us an example of `Mr.UseCase` implementation. Let's take a quick look at the following piece of code:
```typescript
import { MrUseCase } from 'mr-use-case';
import { User } from '$path';
import { isEmail } from '$path';
interface Request {
email: string;
}
interface Response {
user: User;
}
export class UserCreateCase extends MrUseCase() {
private position?: UserPosition;
private positionValidated: UserPosition;
// process
async process() {
await this.assignVariables();
await this.validate(); // calls checks()
const user = await User.create({
email: this.request.email,
positionId: this.positionValidated.id,
});
return { user };
}
// private
protected async checks() {
if (!this.request.email) {
this.errors.add('email', 'presence');
}
if (!isEmail(this.request.email)) {
this.errors.add('email', 'format');
}
if (!this.position) {
this.errors.add('email', 'positionFind');
return;
}
this.positionValidated = this.position;
}
private async assignVariables() {
this.position = await findAvailablePosition();
}
private async findAvailablePosition() {
// ...
}
}
```
As you can see, the code is split into four parts:
1. Assigning a variable area
2. Validation
3. Execution
4. Packing response
Keep in mind that one use case must fullfil only one business purpose and give a straight answer about the success of the operation after the call.
Now let's see how we may use it in the positive scenario:
```typescript
const email = 'example@example.com';
const { user } = await UserCreateCase.call({ email });
return user; // => created user
```
However, what happens if the passed value is not an email? Let's change our code and see.
```typescript
const email = 'wrongemail';
try {
const { user } = await UserCreateCase.call({ email });
} catch (err) {
if (err instanceof MrError) {
debug(err.errors.messages());
return;
}
throw err;
}
```
In this scenario our use case throws an exception containing all errors that were caught by the validation process. You may read more about the errors format at [🥞 Mr.Error page](https://github.com/IlyaDonskikh/mr-error).
Let's make a conclusion.
> ⚠️ At this moment you probably would like to see an integration of the module to something more ready to use. And specifically for this purpose [🐨 Mr.Koa boilerplate](https://github.com/IlyaDonskikh/mrkoa) exists.
## Conclusion
The use cases make your work much simpler, more structured and efficient. And `Mr.UseCase` pleasantly provides an interface to enjoy these advantages with no headache.
Give it a try!
---
_Source: https://npm.io/package/mr-use-case · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._