Add --extra-templates option

[righ]

#755

This is a change to add the --extra-templates option.
It works the same way as --templates, but we don't need to specify original templates.

The following is a log of the test run.

Preparing:

# build a binary at my sqlboiler repository dir.
root@517e8bbfecb1:/sqlboiler# go build -o sqlboiler .
# copy
root@517e8bbfecb1:/sqlboiler# cp sqlboiler /root/
root@517e8bbfecb1:/sqlboiler# cd /root/

root@517e8bbfecb1:~# mkdir templates

root@517e8bbfecb1:~# cat << EOL > templates/99_tablename.go.tpl
> {{- \$alias := .Aliases.Table .Table.Name -}}
>
> // GetTableName returns the real table name.
> func (_ {{\$alias.UpSingular}}) GetTableName() string { return "{{.Table.Name}}" }
> EOL

root@517e8bbfecb1:~# cat templates/99_tablename.go.tpl
{{- $alias := .Aliases.Table .Table.Name -}}

// GetTableName returns the real table name.
func (_ {{$alias.UpSingular}}) GetTableName() string { return "{{.Table.Name}}" }

Execution:

root@517e8bbfecb1:~# ./sqlboiler
Error: must provide a driver name

SQL Boiler generates a Go ORM from template files, tailored to your database schema.
Complete documentation is available at http://github.com/volatiletech/sqlboiler

Usage:
  sqlboiler [flags] <driver>

Examples:
sqlboiler psql

Flags:
      --add-global-variants        Enable generation for global variants
      --add-panic-variants         Enable generation for panic variants
      --add-soft-deletes           Enable soft deletion by updating deleted_at timestamp
  -c, --config string              Filename of config file to override default lookup
  -d, --debug                      Debug mode prints stack traces on error
      --extra-templates strings    The additional templates directory, that does not override the bindata's template folders in sqlboiler
  -h, --help                       help for sqlboiler
      --no-auto-timestamps         Disable automatic timestamps for created_at/updated_at
      --no-back-referencing        Disable back referencing in the loaded relationship structs
      --no-context                 Disable context.Context usage in the generated code
      --no-driver-templates        Disable parsing of templates defined by the database driver
      --no-hooks                   Disable hooks feature for your models
      --no-rows-affected           Disable rows affected in the generated API
      --no-tests                   Disable generated go test files
  -o, --output string              The name of the folder to output to (default "models")
  -p, --pkgname string             The name you wish to assign to your generated package (default "models")
  -r, --relation-tag string        Relationship struct tag name (default "-")
      --struct-tag-casing string   Decides the casing for go structure tag names. camel, title or snake (default snake) (default "snake")
  -t, --tag strings                Struct tags to be included on your models in addition to json, yaml, toml
      --tag-ignore strings         List of column names that should have tags values set to '-' (ignored during parsing)
      --templates strings          A templates directory, overrides the bindata'd template folders in sqlboiler
      --version                    Print the version
      --wipe                       Delete the output folder (rm -rf) before generation to ensure sanity

root@517e8bbfecb1:~# ./sqlboiler mysql --output models_mysql --pkgname models_mysql --wipe --extra-templates ./templates/

root@517e8bbfecb1:~# tail models_mysql/jets.go  -n20
        var exists bool
        sql := "select exists(select 1 from `jets` where `id`=? limit 1)"

        if boil.IsDebug(ctx) {
                writer := boil.DebugWriterFrom(ctx)
                fmt.Fprintln(writer, sql)
                fmt.Fprintln(writer, iD)
        }
        row := exec.QueryRowContext(ctx, sql, iD)

        err := row.Scan(&exists)
        if err != nil {
                return false, errors.Wrap(err, "models_mysql: unable to check if jets exists")
        }

        return exists, nil
}

// GetTableName returns the real table name.
func (_ Jet) GetTableName() string { return "jets" }

[Darkclainer]

Don't you mind if I will amend README.md as additional commit in this PR?

[righ]

@Darkclainer Of cource I do not. Thanks!

[Darkclainer]

@righ
I have found that PR should be opened against dev branch: https://github.com/volatiletech/sqlboiler/blob/master/CONTRIBUTING.md

[righ]

Okay, thanks for letting me know.
I changed the base and rebased this branch onto dev.

And I fixed your commit slightly to match the current code.

[aarondl]

Hello @righ. I appreciate the PR! I don't think it's a good idea to add a second option for templates though. I quite like the explicitness of the current system and I think it's also important to ensure that sqlboiler upgrades don't change your main templates, since your overriding/extra templates can depend on things declared in those and there are many unexported things we could currently change that may break your templates.

I could possibly be convinced but as I see it there's no difference between:

--extra-templates my_dir

and

--templates my_sqlboiler_templates --templates my_dir

The second isn't really onerous enough for me to want to accept this. Besides if you're doing it from a Go module path then you can use: $GOPATH/pkg/mod/github.com/volatiletech/sqlboiler@version as a way of maintaining compatibility which is also nice.

Going to close for now.

[jaakkotuosa]

In case someone else is checking this issue, I would like to mention a more complete example of including the default templates:
--templates $GOPATH/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.1.2/templates --templates $GOPATH/pkg/mod/github.com/volatiletech/sqlboiler/v4@v4.1.2/templates_test