Add Example: With DI

[one-aalam]

Bud's impressive and I understand it's just 0.1, so it would be highly ambitious(and very, very early) to expect a very good documentation, blog and example ecosystem. But, just to give it a consideration as a very low priority task - will it be possible for you to consider adding an example with DI(Env, DB, etc.) ? I'm not a seasoned Go dev, and I think seeing a good example with DI can help anybody like me, even the developers that Bud might inevitably attract due to its affinity towards modern FE frameworks.

[matthewmueller]

Thanks for opening this issue @one-aalam! I'll definitely need to add more examples.

Did you see: https://www.notion.so/Hey-Bud-4d81622cc49942f9917c5033e5205c69#976e4b0666f34d5eae6ccbce93111025? Could I improve the example in there?

One more example I can share now: In the demo video, I show, but don't explicitly mention the dependency injection.

That *hackernews.Client is automatically wired up. The function it calls is here: https://github.com/matthewmueller/hackernews/blob/6eef99e306e59c859d5e14e8ca655acb31cd5fe7/client.go#L23-L25

Basically DI looks for a way to provide a *hackernews.Client to the Controller, it finds that if it calls the New() function it will be able to provide it, so it generates the code to call the New() function.

(FYI I converted this issue to a discussion since it's not a bug)

[one-aalam]

Thanks @matthewmueller This should do for now.

I was looking for an example with DB, env, etc. that shows how something like a DB connection is established/released(for different environments), provided in main, injected in modules and later used for querying and updates(like a full CRUD example with DB)

[matthewmueller]

Ah, so you can do this manually or wait for v0.3 which will ship with environment support.

To do it manually, you can use https://github.com/caarlos0/env and do the following (untested):

1. Create an env/env.go file:

package env

import "github.com/caarlos0/env"

// Load the environment
func Load() (*Env, error) {
  var e Env
  if err := env.Parse(&env); err != nil {
    return err
  }
  return &e, nil
}


type Env struct {
  DatabaseURL string `env:DATABASE_URL`
}

Then in a db/db.go file:

package db

import "app.com/env"
import "github.com/jackc/pgx"

func Dial(env *env.Env) (*Client, error) {
  return pgx.Dial(env.DatabaseURL)
}

type Client = pgx.Client

Finally in your controller/controller.go:

package controller

import "app.com/db"

type Controller struct {
  DB *db.Client
}

type User struct {
  Name string
}

func (c *Controller) Index() ([]*User, error) {
  rows, err := c.DB.Query("select * from users")
  if err != nil {
    return nil, err
  }
  // TODO: turn rows into users
  return users, nil
}

With that you can now switch out your development database with your production database using:

DATABASE_URL="..." bud run

In v0.3, Bud will ship with 4 default environments and a bit more structure around how to do environment management. This example is the basis for the support though.

Please give it a try and let me know if you run into anything or have anymore questions!

[one-aalam]

Thank you, @matthewmueller that's all! :-)

Looking forward to 0.3 which will have the env support baked in, but this is more than enough for me for now.