add extraTag directive

[j75689]

#463

1. add a custom directive to your schema

directive @extraTag on INPUT_FIELD_DEFINITION
    | FIELD_DEFINITION

type Customer {
    website: String @extraTag(gorm: "VARCHAR(255)")
}

2. execute gqlgen cli, and you got the model with tags

type Customer struct {
	Website *string `json:"website" gorm:"VARCHAR(255)"`
}

I have:

• Added tests covering the bug / feature (see testing)
• Updated any relevant documentation (see docs)

[mojtabacazi]

Is this going to be merged soon?

[frederikhors]

It would be amazing to use this today! Please, team, please.

[christian-heusel]

Whats is holding back the merge here? This would be a really great feature and is only approved so far 😊

[milosgajdos]

Oh this would be wonderful. It would open up gqlgen to many other codegen tools. The more code we can gen the better.

[novikov1337danil]

This is very important for many people!
Until this PR has not been adopted, please tell me how you implemented this?

[kfirufk]

@novikov1337danil - i was able to easy implement it using the modelgen hook.

https://gqlgen.com/recipes/modelgen-hook/

[novikov1337danil]

@novikov1337danil - i was able to easy implement it using the modelgen hook.

https://gqlgen.com/recipes/modelgen-hook/

Unfortunately I don't understand how I can specify custom tags for each field.
Could you tell how you did it?

[kfirufk]

@novikov1337danil - i created the following script to create a db tag using the name of the field. of course you can customize it any way you want. so i execute this script instead of executing gqlgen command line.

package main

import (
	"fmt"
	"os"

	"github.com/99designs/gqlgen/api"
	"github.com/99designs/gqlgen/codegen/config"
	"github.com/99designs/gqlgen/plugin/modelgen"
)

// Defining mutation function
func mutateHook(b *modelgen.ModelBuild) *modelgen.ModelBuild {
	for _, model := range b.Models {
		for _, field := range model.Fields {
			field.Tag += ` db:"` + field.Name + `"`
		}
	}

	return b
}

func main() {
	cfg, err := config.LoadConfigFromDefaultLocations()
	if err != nil {
		fmt.Fprintln(os.Stderr, "failed to load config", err.Error())
		os.Exit(2)
	}

	// Attaching the mutation function onto modelgen plugin
	p := modelgen.Plugin{
		MutateHook: mutateHook,
	}

	err = api.Generate(cfg,
		api.NoPlugins(),
		api.AddPlugin(&p),
	)
	if err != nil {
		fmt.Fprintln(os.Stderr, err.Error())
		os.Exit(3)
	}
}

[novikov1337danil]

@kfirufk Thanks for the example provided!
However I am looking for a way to specify my custom tags for EACH field in type (as suggested in PR).
I think this can be achieved using directives, however I do not yet understand how to do it. Do you have any no ideas?

[kfirufk]

@novikov1337danil - for a custom rule for each field, as far as i know, there isn't any easy way to implement that. you can save some sort of config that has the column name and it's related custom tags, and then loop between each field in the config and append the relevant tag/tags to each column.

[sooxt98]

May i know the estimate time for this PR to get merge?

[liam-lai]

bump!

[syssam]

@mtibben @lwc any news?

[johnmaguire]

Great to see this merged! This might be pedantic, but might this get renamed @goTags instead of @extraTag prior to release? gqlgen currently has two built-in directives: @goField and @goModel.

Directives can be used for many purposes, such as signalling constraints to clients. However, for all three built-in directives they're useful only for the Go code generation process. Denoting such with the @go prefix makes a lot of sense to me.

Also the feature seems to support multiple tags (i.e. goTags) not a single tag (goTag), which could be clarified in its name (currently @extraTag.)

cc @StevenACoffman since you merged this, not sure the best way to get eyes on this.

[wilhelmeek]

@johnmaguire very much agree with you. I'll put together a pull request to rename and explicitly support multiples.

[wilhelmeek]

@johnmaguire I've got a PR here if you're keen to have a look

• Rename @extraTag directive to @goTag and make repeatable #1680