Postgres arrays returned as string

[ghost]

I have this table:

create table sessions (
    id uuid primary key default gen_random_uuid(),
    user_id uuid not null references users(id) on delete cascade,
    identifier text not null default '',
    scopes text[] not null default '{}'
);

However, it generates this code:

type Sessions struct {
	ID         uuid.UUID `sql:"primary_key"`
	UserID     uuid.UUID
	Identifier string
	Scopes     string
}

scopes has been emitted as string rather than []string, and results in the funny Postgres {foo, bar} string. Is it possible to scan directly into an array?

[go-jet]

Jet currently doesn't have support for arrays.
Until it gets support you can do something like this:

type Session struct {
    model.Sessions
}

func (s Session) GetScopes() []string {
  return ... convert s.Scopes to []string
}

func (s* Session) SetScopes(scopes []string) {
   s.Scopes = ... convert []string into postgres array representation.
}

[ghost]

Thanks, here's my sketchy workaround for pgx:

package pg

import (
	"github.com/jackc/pgtype"
)

func DecodeTextArray(s string) ([]string, error) {
	ta := &pgtype.TextArray{}
	if err := ta.Scan(s); err != nil {
		return nil, err
	}

	arr := make([]string, len(ta.Elements))
	for i, text := range ta.Elements {
		arr[i] = text.String
	}

	return arr, nil
}

func EncodeTextArray(arr []string) (string, error) {
	elements := make([]pgtype.Text, len(arr))
	for i, s := range arr {
		elements[i] = pgtype.Text{
			Status: pgtype.Present,
			String: s,
		}
	}

	v, err := (&pgtype.TextArray{
		Elements: elements,
		Dimensions: []pgtype.ArrayDimension{
			{Length: int32(len(arr)), LowerBound: 1},
		},
		Status: pgtype.Present,
	}).Value()
	if err != nil {
		return "", err
	}

	if v == nil {
		return "{}", nil
	}

	return v.(string), nil
}

[go-jet]

Ability to change field type of generated model type is now added to develop branch. Sample usage can be seen here.
For jet to be able to handle string arrays correctly a new type is needed. This type will handle conversion from and to db array format.
For instance:

type StringArray []string

func (s StringArray) Scan(value interface{}) error {
   ...
}

func (s StringArray) Value() (driver.Value, error) {
  ...
}

[go-jet]

Ability to change field type of generated model type is included in v2.6.0 release.

[sadensmol]

Hi @go-jet can you please clarify , how this could be used with cli generator?

[go-jet]

It can't be used from cli generator, only from Generator customization.

[sadensmol]

thanks for the clarification! :(

[Hetch3t]

For anyone looking for implementation, here what works for me:

import (
	"database/sql/driver"
	"strings"
)

type StringArray []string

func (s *StringArray) Scan(value interface{}) error {
	input := strings.Trim(value.(string), "{}")
	*s = StringArray(strings.Split(input, ","))

	return nil
}

func (s StringArray) Value() (driver.Value, error) {
	return "{" + strings.Join(s, ",") + "}", nil
}

And in your custom generator you should add:

func useArray(f *template.TableModelField, t metadata.Table, c metadata.Column) {
	if c.DataType.Kind == metadata.ArrayType {
		if c.DataType.Name == "text" {
			// Note that StringArray should be in separate package
			f.Type = template.NewType(typings.StringArray{})
		}
	}
}

And a few lines of code later:

...

UseModel(template.DefaultModel().
	UseTable(func(t metadata.Table) template.TableModel {
		return template.DefaultTableModel(t).
			UseField(func(c metadata.Column) template.TableModelField {
				defaultTableModelField := template.DefaultTableModelField(c)

				useArray(&defaultTableModelField, t, c)

				return defaultTableModelField
			})
	})

...

[adriantofan]

instead of defining a new type it is possible to use directly pq.StringArray in the generator, which is a bit more sophisticated at the implementation level