How to get path from config file

Question

I would like to get path to my sqlite DB from a config file. How could I do that in Go?

This is a code, which I wrote before:

database, _ := sql.Open("sqlite3", "C:\\Users\\username\\project\\source.db")

In this case my path is "hard coded" directly in code. I would like to set a variable, which takes a path from a config data.

What format is your config file? is it JSON, or XML, YAML perhaps? or something else? — mkopriva, Nov 23 '19 at 13:04
@mkopriva i would like to do it with YAML. I founded some modules for it (Viper and go-yaml). — Egor Kado, Nov 23 '19 at 13:07
Those two packages work in different ways, so it is important to know which one of them you chose so that we can provide accurate solutions. — mkopriva, Nov 23 '19 at 13:15
@mkopriva, ok, could you please tell me then, how could i implement it with go-yaml? — Egor Kado, Nov 23 '19 at 13:24

score 0 · Accepted Answer · edited Nov 23 '19 at 18:26

My first suggestion is that you use a JSON file rather than a YAML file for configuration, since Go supports it natively; you don't need to use any external packages.

type DBConfig struct {
    Path string `json:"path"`
}

func loadConfig(path string) (*DBConfig, error) {
    data, err := ioutil.ReadFile(path)
    if err != nil {
        return nil, err
    }

    var conf DBConfig
    err = json.Unmarshal(data, &conf)
    if err != nil {
        return nil, err
    }

    return &conf, nil   
}

My second suggestion is that you pass in the path to this config file in as a flag. You can supply a flag when you run your application like this:

$ go build . -o MyApp
$ ./MyApp --config=path/to/config/file

Flags are very powerful and allow you to easily configure your applications without changing much code. Using flags in Golang is simple.

var configPath = flag.String("config", "", "Path to file containing app config")

Just make sure that you add flag.Parse to the top of your main function in order to access them.

Here's a full example.

Good luck!

Go has excellent support for YAML, too. No reason to use JSON if you prefer YAML (and I generally do prefer YAML, or better, TOML, for configuration) — Jonathan Hall, Nov 23 '19 at 18:27
Of course, you should go with what's best for your project and what you're most comfortable. But for the sake of simplicity, it's often handy to use what's build into the languages standard lib rather than relying on a third party lib. — Nick Corin, Nov 23 '19 at 18:53

How to get path from config file

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