Compare · 007

Enums as generated Go types, and your own types with go_type: PostgreSQL and MySQL

Every file of the PostgreSQL and MySQL versions side by side, with the lines that differ marked. 1 parameter or column types differ in Go.

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Configuration

sgl.yamldiffers
PostgreSQL
MySQL
1version: 1
1version: 1
2
2
3databases:
3databases:
4 - name: harbour
4 - name: menu
5 dialect: postgres
5 dialect: mysql
6 migrations: db/migrations
6 migrations: db/migrations
7 queries: db/queries
7 queries: db/queries
8 go:
8 go:
9 package: store
9 package: store
10 out: internal/store
10 out: internal/store
11 driver: database/sql
11 types:
12 overrides:
13 - column: menu_items.status
14 go: seagull.sh/seagull/examples/mysql/007_enums/internal/menu.Status

Migrations

db/migrations/0001_boats.up.sqldiffers
PostgreSQL
MySQL · db/migrations/0001_menu.up.sql
1CREATE TYPE boat_status AS ENUM ('moored', 'at_sea', 'dry_dock');
1CREATE TABLE menu_items (
2
2 id BIGINT NOT NULL AUTO_INCREMENT PRIMARY KEY,
3CREATE TABLE boats (
3 name VARCHAR(50) NOT NULL UNIQUE,
4 id BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
4 section ENUM('fish', 'sides', 'puddings') NOT NULL,
5 name TEXT NOT NULL,
5 status ENUM('available', 'sold_out') NOT NULL DEFAULT 'available'
6 status boat_status NOT NULL DEFAULT 'moored'
7);
6);
db/migrations/0001_boats.down.sqldiffers
PostgreSQL
MySQL · db/migrations/0001_menu.down.sql
1DROP TABLE boats;
1DROP TABLE menu_items;
2DROP TYPE boat_status;

Queries

AddBoatonly PostgreSQL
PostgreSQL · db/queries/boats.sql
MySQL · not in this version
1-- sgl.query(AddBoat, exec)
2INSERT INTO boats (name, status) VALUES ($1, $2);
SetStatusdiffers
PostgreSQL · db/queries/boats.sql
MySQL · db/queries/menu.sql
1-- sgl.query(SetStatus, execrows)
1-- sgl.query(SetStatus, execrows)
2UPDATE boats SET status = $1 WHERE name = $2;
2UPDATE menu_items SET status = ? WHERE name = ?;
ListBoatsonly PostgreSQL
PostgreSQL · db/queries/boats.sql
MySQL · not in this version
1-- sgl.query(ListBoats, many)
2SELECT name, status FROM boats ORDER BY id;
BoatsWithStatusonly PostgreSQL
PostgreSQL · db/queries/boats.sql
MySQL · not in this version
1-- sgl.query(BoatsWithStatus, many)
2-- sgl.column(status, go_type: "seagull.sh/seagull/examples/postgres/007_enums/internal/harbour.Status")
3SELECT name, status FROM boats WHERE status = $1 ORDER BY id;
AddItemonly MySQL
PostgreSQL · not in this version
MySQL · db/queries/menu.sql
1-- sgl.query(AddItem, exec)
2INSERT INTO menu_items (name, section) VALUES (?, ?);
ListMenuonly MySQL
PostgreSQL · not in this version
MySQL · db/queries/menu.sql
1-- sgl.query(ListMenu, many)
2SELECT name, section, status FROM menu_items ORDER BY section, name;
ItemsInSectiononly MySQL
PostgreSQL · not in this version
MySQL · db/queries/menu.sql
1-- sgl.query(ItemsInSection, many)
2-- sgl.column(section, go_type: "seagull.sh/seagull/examples/mysql/007_enums/internal/menu.Section")
3SELECT name, section, status FROM menu_items WHERE section = ? ORDER BY name;

What sgl generates

AddBoatonly PostgreSQL
PostgreSQL
MySQL · not in this version
1func (queries *Queries) AddBoat(ctx context.Context, params AddBoatParams) error
2
3type AddBoatParams struct {
4 Name string
5 Status BoatStatus
6}
7
8type BoatStatus string
SetStatusdiffers
PostgreSQL
MySQL
1func (queries *Queries) SetStatus(ctx context.Context, params SetStatusParams) (int64, error)
1func (queries *Queries) SetStatus(ctx context.Context, params SetStatusParams) (int64, error)
2
2
3type SetStatusParams struct {
3type SetStatusParams struct {
4 Status BoatStatus
4 Status menu.Status
5 Name string
5 Name string
6}
6}
7
8type BoatStatus string
ListBoatsonly PostgreSQL
PostgreSQL
MySQL · not in this version
1func (queries *Queries) ListBoats(ctx context.Context) ([]ListBoatsRow, error)
2
3type ListBoatsRow struct {
4 Name string `json:"name"`
5 Status BoatStatus `json:"status"`
6}
7
8type BoatStatus string
BoatsWithStatusonly PostgreSQL
PostgreSQL
MySQL · not in this version
1func (queries *Queries) BoatsWithStatus(ctx context.Context, status BoatStatus) ([]BoatsWithStatusRow, error)
2
3type BoatStatus string
4
5type BoatsWithStatusRow struct {
6 Name string `json:"name"`
7 Status harbour.Status `json:"status"`
8}
AddItemonly MySQL
PostgreSQL · not in this version
MySQL
1func (queries *Queries) AddItem(ctx context.Context, params AddItemParams) error
2
3type AddItemParams struct {
4 Name string
5 Section MenuItemsSection
6}
7
8type MenuItemsSection string
ListMenuonly MySQL
PostgreSQL · not in this version
MySQL
1func (queries *Queries) ListMenu(ctx context.Context) ([]ListMenuRow, error)
2
3type ListMenuRow struct {
4 Name string `json:"name"`
5 Section MenuItemsSection `json:"section"`
6 Status menu.Status `json:"status"`
7}
8
9type MenuItemsSection string
ItemsInSectiononly MySQL
PostgreSQL · not in this version
MySQL
1func (queries *Queries) ItemsInSection(ctx context.Context, section MenuItemsSection) ([]ItemsInSectionRow, error)
2
3type MenuItemsSection string
4
5type ItemsInSectionRow struct {
6 Name string `json:"name"`
7 Section menu.Section `json:"section"`
8 Status menu.Status `json:"status"`
9}

The program

example.godiffers
PostgreSQL
MySQL
1package main
1package main
2
2
3import (
3import (
4 "context"
4 "context"
5 "database/sql"
5 "database/sql"
6 "errors"
6 "errors"
7 "fmt"
7 "fmt"
8 "io"
8 "io"
9
9
10 "seagull.sh/seagull/examples/postgres/007_enums/internal/store"
10 "seagull.sh/seagull/examples/mysql/007_enums/internal/menu"
11 "seagull.sh/seagull/examples/mysql/007_enums/internal/store"
11)
12)
12
13
13// run gives the harbour's boats a status from the boat_status enum and lists them twice.
14// run fills a chip shop menu whose section and status columns are MySQL ENUMs, marks an
14// The enum becomes a named Go type in the generated package: models.go declares
15// item sold out and reads the menu back. Each ENUM becomes a named Go type in the
15// store.BoatStatus, named after the enum type, with a constant for each label, such as
16// generated package unless an override names a type of your own:
16// store.BoatStatusMoored, and a Valid method. Every column and parameter of the enum
17// takes it, in models.go, in Params structs and in Row structs, as ListBoats shows. Valid
18// reports whether a value is one of the labels, and the server still enforces them, so a
19// status outside the enum is refused when the statement runs.
20//
17//
21// For a type of your own, here harbour.Status with a method that describes each label,
18// - section has no override, so models.go declares store.MenuItemsSection, named after
22// name it with a go_type override. BoatsWithStatus does that for one query with
19// the table and column that hold the ENUM, with a constant for each value, such as
23// sgl.column(status, go_type: ...); a types.overrides entry in sgl.yaml, naming the enum
20// store.MenuItemsSectionFish, and a Valid method; ListMenuRow.Section,
24// type boat_status or the column boats.status, would do it for every query, and for the
21// AddItemParams.Section and ItemsInSection's parameter are all a
25// parameters bound to the column too. A query's sgl.column override changes only that
22// store.MenuItemsSection;
26// query's returned column, so AddBoat, SetStatus and BoatsWithStatus's own parameter
23// - sgl.yaml's types.overrides names the column menu_items.status, so every query that
27// still take the generated store.BoatStatus.
24// returns it as it is gives menu.Status, as in ListMenuRow.Status, and so does every
25// parameter compared with or assigned to it, as in SetStatusParams.Status; models.go
26// uses it too, and the generated package declares no type for that ENUM;
27// - sgl.column(section, go_type: ...) in ItemsInSection gives that one query's returned
28// Section the type menu.Section; the parameter it compares with stays a
29// store.MenuItemsSection.
28//
30//
31// An ENUM sorts in the order its values are declared, not alphabetically, so ORDER BY
32// section lists fish, then sides, then puddings. Valid reports whether a value is one the
33// ENUM declares, so the shop can check a section before it binds it. In strict mode, the
34// default since MySQL 5.7, a value the ENUM does not list is refused as it is stored as
35// well; MySQL keeps an ENUM as the index of its value, and its error says the value was
36// truncated.
37//
29// Takes database (*sql.DB) which is a migrated database.
38// Takes database (*sql.DB) which is a migrated database.
30// Takes output (io.Writer) which receives both listings.
39// Takes output (io.Writer) which receives the menu, the fish section and the refusal.
31//
40//
32// Returns error when a query fails or a status outside the enum is accepted.
41// Returns error when a query fails other than as the example expects.
33func run(ctx context.Context, database *sql.DB, output io.Writer) error {
42func run(ctx context.Context, database *sql.DB, output io.Writer) error {
34 queries := store.New(database)
43 queries := store.New(database)
35
44
36 boats := []store.AddBoatParams{
45 items := []store.AddItemParams{
37 {Name: "Kittiwake", Status: store.BoatStatusMoored},
46 {Name: "cod", Section: store.MenuItemsSectionFish},
38 {Name: "Salty Chip", Status: store.BoatStatusAtSea},
47 {Name: "haddock", Section: store.MenuItemsSectionFish},
39 {Name: "Gull Wing", Status: store.BoatStatusDryDock},
48 {Name: "chips", Section: store.MenuItemsSectionSides},
40 {Name: "Driftwood", Status: store.BoatStatusMoored},
49 {Name: "mushy peas", Section: store.MenuItemsSectionSides},
50 {Name: "sticky toffee pudding", Section: store.MenuItemsSectionPuddings},
41 }
51 }
42 for _, boat := range boats {
52 for _, item := range items {
43 if err := queries.AddBoat(ctx, boat); err != nil {
53 if err := queries.AddItem(ctx, item); err != nil {
44 return fmt.Errorf("adding %s: %w", boat.Name, err)
54 return fmt.Errorf("adding %s: %w", item.Name, err)
45 }
55 }
46 }
56 }
47
57 if _, err := queries.SetStatus(ctx, store.SetStatusParams{Status: menu.SoldOut, Name: "haddock"}); err != nil {
48 sunk := store.BoatStatus("sunk")
58 return fmt.Errorf("selling out of haddock: %w", err)
49 if err := queries.AddBoat(ctx, store.AddBoatParams{Name: "Wreck", Status: sunk}); err == nil {
50 return errors.New("adding a boat with status sunk: got no error, want the enum to refuse it")
51 }
52 fmt.Fprintf(output, "status %q: Valid() is %t, and the server refuses it, as it is not a boat_status label\n", sunk, sunk.Valid())
53
54 if _, err := queries.SetStatus(ctx, store.SetStatusParams{Status: store.BoatStatusAtSea, Name: "Kittiwake"}); err != nil {
55 return fmt.Errorf("sending Kittiwake to sea: %w", err)
56 }
59 }
57
60
58 listed, err := queries.ListBoats(ctx)
61 listed, err := queries.ListMenu(ctx)
59 if err != nil {
62 if err != nil {
60 return fmt.Errorf("listing boats: %w", err)
63 return fmt.Errorf("listing the menu: %w", err)
61 }
64 }
62 fmt.Fprintln(output, "\nListBoats, where status is the generated store.BoatStatus:")
65 var menuRow store.ListMenuRow
63 for _, boat := range listed {
66 fmt.Fprintf(output, "ListMenu: section %T, status %T\n", menuRow.Section, menuRow.Status)
64 fmt.Fprintf(output, " %-10s %-8s %T\n", boat.Name, boat.Status, boat.Status)
67 for _, item := range listed {
68 fmt.Fprintf(output, " %-9s %s%s\n", item.Section, item.Name, soldOut(item.Status))
65 }
69 }
66
70
67 atSea, err := queries.BoatsWithStatus(ctx, store.BoatStatusAtSea)
71 fish, err := queries.ItemsInSection(ctx, store.MenuItemsSectionFish)
68 if err != nil {
72 if err != nil {
69 return fmt.Errorf("listing boats at sea: %w", err)
73 return fmt.Errorf("listing the fish: %w", err)
70 }
74 }
71 fmt.Fprintln(output, "\nBoatsWithStatus, where a go_type override makes status a harbour.Status:")
75 var sectionRow store.ItemsInSectionRow
72 for _, boat := range atSea {
76 fmt.Fprintf(output, "ItemsInSection: section %T, status %T\n", sectionRow.Section, sectionRow.Status)
73 fmt.Fprintf(output, " %-10s %-14s %T\n", boat.Name, boat.Status.Describe(), boat.Status)
77 for _, item := range fish {
78 fmt.Fprintf(output, " %-9s %s%s\n", item.Section, item.Name, soldOut(item.Status))
74 }
79 }
80
81 drinks := store.MenuItemsSection("drinks")
82 fmt.Fprintf(output, "section drinks is valid: %t\n", drinks.Valid())
83 err = queries.AddItem(ctx, store.AddItemParams{Name: "lemonade", Section: drinks})
84 if err == nil {
85 return errors.New("added an item to a section the enum does not list")
86 }
87 fmt.Fprintf(output, "refused section drinks: %v\n", err)
75 return nil
88 return nil
76}
89}
90
91// soldOut returns a note for an item that has sold out, comparing against the typed
92// constant rather than a string.
93//
94// Takes status (menu.Status) which is the item's status.
95//
96// Returns string which is the note, or empty when the item is available.
97func soldOut(status menu.Status) string {
98 if status == menu.SoldOut {
99 return " (sold out)"
100 }
101 return ""
102}

Go type differences

The same SQL types map to different Go types, because each database reports them differently.

QueryFieldPostgreSQLMySQL
SetStatusparameter statusBoatStatusmenu.Status