README ¶
PostgreSQL client for Golang
Supports:
- Basic types: integers, floats, string, bool, time.Time.
- sql.NullBool, sql.NullString, sql.NullInt64 and sql.NullFloat64.
sql:",null"
struct tag which marshalls zero struct fields as SQLNULL
and completely omits them fromINSERT
queries.- sql.Scanner and sql/driver.Valuer interfaces.
- Structs, maps and arrays are marshalled as JSON by default.
- PostgreSQL multidimensional Arrays using array tag and Array wrapper.
- Hstore using hstore tag and Hstore wrapper.
- Transactions.
- Prepared statements.
- Notifications using
LISTEN
andNOTIFY
. - Copying data using
COPY FROM
andCOPY TO
. - Timeouts.
- Automatic connection pooling.
- Queries retries on network errors.
- Working with models using ORM and SQL.
- Scanning variables using ORM and SQL.
- SelectOrCreate using upserts.
- INSERT ... ON CONFLICT DO UPDATE using ORM.
- CountEstimate using
EXPLAIN
to get estimated number of matching rows. - HasOne, HasMany and ManyToMany.
- Migrations.
- Sharding.
API docs: http://godoc.org/gopkg.in/pg.v4. Examples: http://godoc.org/gopkg.in/pg.v4#pkg-examples.
Table of contents
Installation
Install:
go get gopkg.in/pg.v4
Quickstart
package pg_test
import (
"fmt"
"gopkg.in/pg.v4"
)
type User struct {
Id int64
Name string
Emails []string
}
func (u User) String() string {
return fmt.Sprintf("User<%d %s %v>", u.Id, u.Name, u.Emails)
}
type Story struct {
Id int64
Title string
AuthorId int64
Author *User
}
func (s Story) String() string {
return fmt.Sprintf("Story<%d %s %s>", s.Id, s.Title, s.Author)
}
func createSchema(db *pg.DB) error {
queries := []string{
`CREATE TEMP TABLE users (id serial, name text, emails jsonb)`,
`CREATE TEMP TABLE stories (id serial, title text, author_id bigint)`,
}
for _, q := range queries {
_, err := db.Exec(q)
if err != nil {
return err
}
}
return nil
}
func ExampleDB_Model() {
db := pg.Connect(&pg.Options{
User: "postgres",
})
err := createSchema(db)
if err != nil {
panic(err)
}
user1 := &User{
Name: "admin",
Emails: []string{"admin1@admin", "admin2@admin"},
}
err = db.Create(user1)
if err != nil {
panic(err)
}
err = db.Create(&User{
Name: "root",
Emails: []string{"root1@root", "root2@root"},
})
if err != nil {
panic(err)
}
story1 := &Story{
Title: "Cool story",
AuthorId: user1.Id,
}
err = db.Create(story1)
if err != nil {
panic(err)
}
// Select user by primary key.
user := User{Id: user1.Id}
err = db.Select(&user)
if err != nil {
panic(err)
}
// Select all users.
var users []User
err = db.Model(&users).Select()
if err != nil {
panic(err)
}
// Select story and associated author in one query.
var story Story
err = db.Model(&story).
Column("story.*", "Author").
Where("story.id = ?", story1.Id).
Select()
if err != nil {
panic(err)
}
fmt.Println(user)
fmt.Println(users)
fmt.Println(story)
// Output: User<1 admin [admin1@admin admin2@admin]>
// [User<1 admin [admin1@admin admin2@admin]> User<2 root [root1@root root2@root]>]
// Story<1 Cool story User<1 admin [admin1@admin admin2@admin]>>
}
Model definition
Models are defined using Go structs. Order of the struct fields usually does not matter with the only exception being primary key(s) that must be defined before any other fields. Otherwise table relationships can be recognized incorrectly.
Please note that most struct tags in following example are not needed and are included only for demonstration purposes.
type Genre struct {
// TableName is an optional field that specifies custom table name and alias.
// By default go-pg generates table name and alias from the struct name.
TableName struct{} `sql:"genres,alias:genre"` // default name and alias are the same
Id int // Id is automatically detected as primary key
Name string
Rating int `sql:"-"` // - is used to ignore field
Books []Book `pg:",many2many:book_genres"` // many to many relation
ParentId int `sql:",null"`
Subgenres []Genre `pg:",fk:Parent"` // fk specifies prefix for foreign key (ParentId)
}
type Author struct {
ID int // both "Id" and "ID" are detected as primary key
Name string
Books []Book // has many relation
}
type BookGenre struct {
TableName struct{} `sql:",alias:bg"` // custom table alias
BookId int `sql:",pk"` // pk tag is used to mark field as primary key
GenreId int `sql:",pk"`
Genre_Rating int // belongs to and is copied to Genre model
}
type Book struct {
Id int
Title string
AuthorID int
Author *Author // has one relation
EditorID int
Editor *Author // has one relation
CreatedAt time.Time `sql:",null"`
Genres []Genre `pg:",many2many:book_genres" gorm:"many2many:book_genres;"` // many to many relation
Translations []Translation // has many relation
Comments []Comment `pg:",polymorphic:Trackable"` // has many polymorphic relation
}
type Translation struct {
TableName struct{} `sql:",alias:tr"` // custom table alias
Id int
BookId int
Book *Book // belongs to relation
Lang string
Comments []Comment `pg:",polymorphic:Trackable"` // has many polymorphic relation
}
type Comment struct {
TrackableId int `sql:",pk"` // Book.Id or Translation.Id
TrackableType string `sql:",pk"` // "book" or "translation"
Text string
}
Writing queries
Select
// Select book by primary key.
err := db.Select(&book)
// SELECT * FROM "books" WHERE id = 1
// Select only book title and text.
err := db.Model(&book).Column("title", "text").Where("id = ?", 1).Select()
// SELECT "title", "text" FROM "books" WHERE id = 1
// Select only book title and text into variables.
var title, text string
err := db.Model(&Book{}).Column("title", "text").Where("id = ?", 1).Select(&title, &text)
// SELECT "title", "text" FROM "books" WHERE id = 1
// Select book using WHERE.
err := db.Model(&book).
Where("id > ?", 100).
Where("title LIKE ?", "my%").
Limit(1).
Select()
// SELECT * FROM "books" WHERE (id > 100) AND (title LIKE 'my%') LIMIT 1
// Select book using WHERE OR.
err := db.Model(&book).
WhereOr(
pg.SQL("id > ?", 100),
pg.SQL("title LIKE ?", "my%"),
).
Limit(1).
Select()
// SELECT * FROM "books" WHERE (id > 100 OR title LIKE 'my%') LIMIT 1
// Select first 20 books.
err := db.Model(&books).Order("id ASC").Limit(20).Select()
// SELECT * FROM "books" ORDER BY id ASC LIMIT 20
// Count books.
count, err := db.Model(&Book{}).Count()
// SELECT COUNT(*) FROM "books"
// Select 20 books and count all books.
count, err := db.Model(&books).Limit(20).SelectAndCount()
// SELECT * FROM "books" LIMIT 20
// SELECT COUNT(*) FROM "books"
// Select 20 books and count estimated number of books.
count, err := db.Model(&books).Limit(20).SelectAndCountEstimate(100000)
// SELECT * FROM "books" LIMIT 20
// EXPLAIN SELECT 2147483647 FROM "books"
// SELECT COUNT(*) FROM "books"
// Select author id and number of books.
var res []struct {
AuthorId int
BookCount int
}
err := db.Model(&Book{}).
Column("author_id").
ColumnExpr("count(*) AS book_count").
Group("author_id").
Order("book_count DESC").
Select(&res)
// SELECT "author_id", count(*) AS book_count
// FROM "books" AS "book"
// GROUP BY author_id
// ORDER BY book_count DESC
// Select book ids as PostgreSQL array.
var ids []int
err := db.Model(&Book{}).ColumnExpr("array_agg(id)").Select(pg.Array(&ids))
// SELECT array_agg(id) FROM "books"
Reusing queries
// pager retrieves page number from the req and sets query LIMIT and OFFSET.
func pager(req *http.Request) func(*orm.Query) *orm.Query {
const pageSize = 20
return func(q *orm.Query) *orm.Query {
param := req.URL.Query().Get("page")
if param == "" {
return q
}
page, err := strconv.Atoi(param)
if err == nil {
q = q.Offset((page - 1) * pageSize).Limit(pageSize)
}
return q
}
}
var books []Book
err := db.Model(&books).Apply(pager(req)).Select()
// SELECT * FROM "books" LIMIT 20
Insert
// Insert new book returning primary keys.
err := db.Create(&book)
// INSERT INTO "books" (title, text) VALUES ('my title', 'my text') RETURNING "id"
// Insert new book returning all columns.
err := db.Model(&book).Returning("*").Create()
// INSERT INTO "books" (title, text) VALUES ('my title', 'my text') RETURNING *
// Select existing book by name or create new book.
err := db.Model(&book).
Where("title = ?title").
OnConflict("DO NOTHING"). // optional
SelectOrCreate()
// 1. SELECT * FROM "books" WHERE title = 'my title'
// 2. INSERT INTO "books" (title, text) VALUES ('my title', 'my text') RETURNING "id"
// 3. go to step 1 on error
// Create new book or update existing one.
_, err := db.Model(book).
OnConflict("(id) DO UPDATE").
Set("title = ?title").
Create()
// INSERT INTO "books" ("id", "title") VALUES (100, 'my title')
// ON CONFLICT (id) DO UPDATE SET title = 'title version #1'
Update
// Update all columns except primary keys.
err := db.Update(&book)
// UPDATE "books" SET title = 'my title', text = 'my text' WHERE id = 1
// Update only column "title".
res, err := db.Model(&book).Set("title = ?title").Where("id = ?id").Update()
// UPDATE "books" SET title = 'my title' WHERE id = 1
// Update only column "title".
res, err := db.Model(&book).Column("title").Update()
// UPDATE "books" SET title = 'my title' WHERE id = 1
Delete
// Delete book by primary key.
err := db.Delete(&book)
// DELETE FROM "books" WHERE id = 1
// Delete book by title.
res, err := db.Model(&book).Where("title = ?title").Delete()
// DELETE FROM "books" WHERE title = 'my title'
Has one
Following example selects all items and their subitems using LEFT JOIN and sub_id
column.
type Item struct {
Id int
Sub *Item
SubId int
}
var items []Item
err := db.Model(&items).
Column("item.*", "Sub").
Where("item.sub_id IS NOT NULL").
Select()
// SELECT "item".*, "sub"."id" AS "sub__id", "sub"."sub_id" AS "sub__sub_id"
// FROM "items" AS "item"
// LEFT JOIN "items" AS "sub" ON "sub"."id" = item."sub_id"
// WHERE (item.sub_id IS NOT NULL)
Has many
Following example selects one item and all subitems using parent_id
column.
type Item struct {
Id int
Items []Item `pg:",fk:Parent"`
ParentId int
}
var item Item
err := db.Model(&item).Column("item.*", "Items").First()
// SELECT "item".* FROM "items" AS "item" ORDER BY "item"."id" LIMIT 1
//
// SELECT "item".* FROM "items" AS "item" WHERE (("item"."parent_id") IN ((1)))
Has many to many
Following example selects one item and all subitems using itermediary item_to_items
table.
type Item struct {
Id int
Items []Item `pg:",many2many:item_to_items,joinFK:Sub"`
}
err := db.Model(&item).Column("item.*", "Items").First()
// SELECT "item".* FROM "items" AS "item" ORDER BY "item"."id" LIMIT 1
//
// SELECT * FROM "items" AS "item"
// JOIN "item_to_items" ON ("item_to_items"."item_id") IN ((1))
// WHERE ("item"."id" = "item_to_items"."sub_id")
Howto
Please go through examples to get the idea how to use this package.
FAQ
Why go-pg
-
No
rows.Close
to manually manage connections. -
go-pg automatically maps rows on Go structs and slice.
-
go-pg is 2x-10x faster than GORM on querying 100 rows from table.
BenchmarkQueryRowsGopgOptimized-4 10000 122138 ns/op 83472 B/op 625 allocs/op BenchmarkQueryRowsGopgReflect-4 10000 137208 ns/op 87488 B/op 736 allocs/op BenchmarkQueryRowsGopgORM-4 10000 142029 ns/op 87920 B/op 741 allocs/op BenchmarkQueryRowsStdlibPq-4 10000 162664 ns/op 161631 B/op 1324 allocs/op BenchmarkQueryRowsGORM-4 2000 569147 ns/op 415272 B/op 6966 allocs/op
-
go-pg generates much more effecient queries for joins.
Has one relationBenchmarkModelHasOneGopg-4 5000 273181 ns/op 62692 B/op 1080 allocs/op BenchmarkModelHasOneGORM-4 500 3320562 ns/op 1528489 B/op 71630 allocs/op
go-pg:
db.Model(&books).Column("book.*", "Author").Limit(100).Select()
SELECT "book".*, "author"."id" AS "author__id", "author"."name" AS "author__name" FROM "books" AS "book" LEFT JOIN "authors" AS "author" ON "author"."id" = "book"."author_id" LIMIT 100
GORM:
db.Preload("Author").Limit(100).Find(&books).Error
SELECT * FROM "books" LIMIT 100 SELECT * FROM "authors" WHERE ("id" IN ('1','2'...'100'))
Has many relationBenchmarkModelHasManyGopg-4 500 2825899 ns/op 311556 B/op 5501 allocs/op BenchmarkModelHasManyGORM-4 200 7538012 ns/op 3333023 B/op 71756 allocs/op
go-pg:
db.Model(&books).Column("book.*", "Translations").Limit(100).Select()
SELECT "book".* FROM "books" AS "book" LIMIT 100 SELECT "translation".* FROM "translations" AS "translation" WHERE ("translation"."book_id") IN ((100), (101), ... (199));
GORM:
db.Preload("Translations").Limit(100).Find(&books).Error
SELECT * FROM "books" LIMIT 100; SELECT * FROM "translations" WHERE ("book_id" IN (1, 2, ..., 100)); SELECT * FROM "authors" WHERE ("book_id" IN (1, 2, ..., 100));
Many to many relationBenchmarkModelHasMany2ManyGopg-4 500 3184262 ns/op 397883 B/op 7523 allocs/op BenchmarkModelHasMany2ManyGORM-4 200 8233222 ns/op 3686341 B/op 77236 allocs/op
go-pg:
db.Model(&books).Column("book.*", "Genres").Limit(100).Select()
SELECT "book"."id" FROM "books" AS "book" LIMIT 100; SELECT * FROM "genres" AS "genre" JOIN "book_genres" AS "book_genre" ON ("book_genre"."book_id") IN ((1), (2), ..., (100)) WHERE "genre"."id" = "book_genre"."genre_id";
GORM:
db.Preload("Genres").Limit(100).Find(&books).Error
SELECT * FROM "books" LIMIT 100; SELECT * FROM "genres" INNER JOIN "book_genres" ON "book_genres"."genre_id" = "genres"."id" WHERE ("book_genres"."book_id" IN ((1), (2), ..., (100)));
How can I view queries this library generates?
You can setup query logger like this:
pg.SetQueryLogger(log.New(os.Stdout, "", log.LstdFlags))
Or you can configure PostgreSQL to log every query by adding following lines to your postgresql.conf (usually /etc/postgresql/9.5/main/postgresql.conf):
log_statement = 'all'
log_min_duration_statement = 0
Then just tail the log file:
tail -f /var/log/postgresql/postgresql-9.5-main.log
Documentation ¶
Overview ¶
Package gopkg.in/pg.v4 implements a PostgreSQL client.
Index ¶
- Variables
- func Array(v interface{}) *types.Array
- func F(field string, params ...interface{}) types.F
- func Hstore(v interface{}) *types.Hstore
- func Q(query string, params ...interface{}) types.Q
- func SQL(query string, params ...interface{}) *orm.SQL
- func Scan(values ...interface{}) orm.ColumnScanner
- func SetLogger(logger *log.Logger)
- func SetQueryLogger(logger *log.Logger)
- type DB
- func (db *DB) Begin() (*Tx, error)
- func (db *DB) Close() error
- func (db *DB) CopyFrom(reader io.Reader, query interface{}, params ...interface{}) (*types.Result, error)
- func (db *DB) CopyTo(writer io.Writer, query interface{}, params ...interface{}) (*types.Result, error)
- func (db *DB) Create(model ...interface{}) error
- func (db *DB) Delete(model interface{}) error
- func (db *DB) Exec(query interface{}, params ...interface{}) (res *types.Result, err error)
- func (db *DB) ExecOne(query interface{}, params ...interface{}) (*types.Result, error)
- func (db *DB) FormatQuery(dst []byte, query string, params ...interface{}) []byte
- func (db *DB) Listen(channels ...string) (*Listener, error)
- func (db *DB) Model(model interface{}) *orm.Query
- func (db *DB) Options() *Options
- func (db *DB) Prepare(q string) (*Stmt, error)
- func (db *DB) Query(model, query interface{}, params ...interface{}) (res *types.Result, err error)
- func (db *DB) QueryOne(model, query interface{}, params ...interface{}) (*types.Result, error)
- func (db *DB) RunInTransaction(fn func(*Tx) error) error
- func (db *DB) Select(model interface{}) error
- func (db *DB) Update(model interface{}) error
- func (db *DB) WithTimeout(d time.Duration) *DB
- type Error
- type IntSet
- type Ints
- type Listener
- type Options
- type Stmt
- func (stmt *Stmt) Close() error
- func (stmt *Stmt) Exec(params ...interface{}) (res *types.Result, err error)
- func (stmt *Stmt) ExecOne(params ...interface{}) (*types.Result, error)
- func (stmt *Stmt) Query(model interface{}, params ...interface{}) (res *types.Result, err error)
- func (stmt *Stmt) QueryOne(model interface{}, params ...interface{}) (*types.Result, error)
- type Strings
- type Tx
- func (tx *Tx) Commit() error
- func (tx *Tx) CopyFrom(r io.Reader, query string, params ...interface{}) (*types.Result, error)
- func (tx *Tx) Create(model ...interface{}) error
- func (tx *Tx) Delete(model interface{}) error
- func (tx *Tx) Exec(query interface{}, params ...interface{}) (*types.Result, error)
- func (tx *Tx) ExecOne(query interface{}, params ...interface{}) (*types.Result, error)
- func (tx *Tx) FormatQuery(dst []byte, query string, params ...interface{}) []byte
- func (tx *Tx) Model(model interface{}) *orm.Query
- func (tx *Tx) Prepare(q string) (*Stmt, error)
- func (tx *Tx) Query(model interface{}, query interface{}, params ...interface{}) (*types.Result, error)
- func (tx *Tx) QueryOne(model interface{}, query interface{}, params ...interface{}) (*types.Result, error)
- func (tx *Tx) Rollback() error
- func (tx *Tx) Select(model interface{}) error
- func (tx *Tx) Stmt(stmt *Stmt) *Stmt
- func (tx *Tx) Update(model interface{}) error
Examples ¶
- Array
- Connect
- DB.Begin
- DB.CopyFrom
- DB.Create
- DB.Create (BulkInsert)
- DB.Create (BulkInsert2)
- DB.Create (OnConflictDoNothing)
- DB.Create (OnConflictDoUpdate)
- DB.Create (SelectOrCreate)
- DB.Delete
- DB.Delete (MultipleRows)
- DB.Exec
- DB.Model
- DB.Model (ApplyFunc)
- DB.Model (Count)
- DB.Model (CountEstimate)
- DB.Model (HasMany)
- DB.Model (HasOne)
- DB.Model (HstoreStructTag)
- DB.Model (ManyToMany)
- DB.Model (NullEmptyValue)
- DB.Model (PostgresArrayStructTag)
- DB.Model (SelectAndCount)
- DB.Prepare
- DB.Query
- DB.QueryOne
- DB.QueryOne (Returning_id)
- DB.RunInTransaction
- DB.Select
- DB.Select (AllColumns)
- DB.Select (FirstRow)
- DB.Select (GroupBy)
- DB.Select (LastRow)
- DB.Select (SomeColumns)
- DB.Select (SomeColumnsIntoVars)
- DB.Select (SqlExpression)
- DB.Select (TableAlias)
- DB.Select (WhereOr)
- DB.Update
- DB.Update (SetValues)
- DB.Update (SomeColumns)
- DB.Update (SomeColumns2)
- DB.WithTimeout
- F
- Hstore
- Ints
- Ints (In)
- Listener
- Q
- Scan
- Strings
Constants ¶
This section is empty.
Variables ¶
var ( ErrNoRows = internal.ErrNoRows ErrMultiRows = internal.ErrMultiRows )
var Discard orm.Discard
Discard is used with Query and QueryOne to discard rows.
Functions ¶
func Array ¶
Array accepts a slice and returns a wrapper for working with PostgreSQL array data type.
Note that for struct fields you should use array tag:
Emails []string `pg:",array"`
Example ¶
Output: [one@example.com two@example.com]
func F ¶
F quotes a SQL identifier such as a table or column name replacing any placeholders found in the field.
Example ¶
Output: Book<Id=1 Title="book 1">
func Hstore ¶
Hstore accepts a map and returns a wrapper for working with hstore data type. Supported map types are:
- map[string]string
Note that for struct fields you should use hstore tag:
Attrs map[string]string `pg:",hstore"`
Example ¶
Output: map[hello:world]
func Q ¶
Q replaces any placeholders found in the query.
Example ¶
Output: Book<Id=1 Title="book 1">
func Scan ¶
func Scan(values ...interface{}) orm.ColumnScanner
Scan returns ColumnScanner that copies the columns in the row into the values.
Example ¶
Output: foo bar <nil>
func SetQueryLogger ¶
SetQueryLogger sets a logger that will be used to log generated queries.
Types ¶
type DB ¶
type DB struct {
// contains filtered or unexported fields
}
DB is a database handle representing a pool of zero or more underlying connections. It's safe for concurrent use by multiple goroutines.
func Connect ¶
Connect connects to a database using provided options.
The returned DB is safe for concurrent use by multiple goroutines and maintains its own connection pool.
Example ¶
Output: <nil>
func (*DB) Begin ¶
Begin starts a transaction. Most callers should use RunInTransaction instead.
Example ¶
Output: 1
func (*DB) Close ¶
Close closes the database client, releasing any open resources.
It is rare to Close a DB, as the DB handle is meant to be long-lived and shared between many goroutines.
func (*DB) CopyFrom ¶
func (db *DB) CopyFrom(reader io.Reader, query interface{}, params ...interface{}) (*types.Result, error)
CopyFrom copies data from reader to a table.
Example ¶
Output: hello,5 foo,3
func (*DB) CopyTo ¶
func (db *DB) CopyTo(writer io.Writer, query interface{}, params ...interface{}) (*types.Result, error)
CopyTo copies data from a table to writer.
func (*DB) Create ¶
Create inserts the model updating primary keys if they are empty.
Example ¶
Output: Book<Id=4 Title="new book">
Example (BulkInsert) ¶
Output: Book<Id=4 Title="new book 1"> Book<Id=5 Title="new book 2">
Example (BulkInsert2) ¶
Output: [Book<Id=4 Title="new book 1"> Book<Id=5 Title="new book 2">]
Example (OnConflictDoNothing) ¶
Output: created did nothing
Example (OnConflictDoUpdate) ¶
Output: Book<Id=100 Title="title version #0"> Book<Id=100 Title="title version #1">
Example (SelectOrCreate) ¶
Output: true Author<ID=2 Name="R. Scott Bakker">
func (*DB) Delete ¶
Delete deletes the model by primary key.
Example ¶
Output: pg: no rows in result set
Example (MultipleRows) ¶
Output: deleted 3 left 0
func (*DB) Exec ¶
Exec executes a query ignoring returned rows. The params are for any placeholder parameters in the query.
Example ¶
Output: -1 <nil>
func (*DB) ExecOne ¶
ExecOne acts like Exec, but query must affect only one row. It returns ErrNoRows error when query returns zero rows or ErrMultiRows when query returns multiple rows.
func (*DB) FormatQuery ¶
func (*DB) Model ¶
Model returns new query for the model.
Example ¶
Output: User<1 admin [admin1@admin admin2@admin]> [User<1 admin [admin1@admin admin2@admin]> User<2 root [root1@root root2@root]>] Story<1 Cool story User<1 admin [admin1@admin admin2@admin]>>
Example (ApplyFunc) ¶
Output: [Book<Id=1 Title="book 1"> Book<Id=2 Title="book 2">]
Example (Count) ¶
Output: 3
Example (CountEstimate) ¶
Output: 3
Example (HasMany) ¶
Output: Item 1 Subitems 2 3
Example (HasOne) ¶
Output: found 2 items item 2, subitem 1 item 4, subitem 2
Example (HstoreStructTag) ¶
Output: {1 map[hello:world]}
Example (ManyToMany) ¶
Output: Item 1 Subitems 2 3
Example (NullEmptyValue) ¶
Output: false
Example (PostgresArrayStructTag) ¶
Output: {1 [one@example.com two@example.com] [[1 2] [3 4]]}
Example (SelectAndCount) ¶
Output: 3 [Book<Id=1 Title="book 1"> Book<Id=2 Title="book 2">]
func (*DB) Prepare ¶
Prepare creates a prepared statement for later queries or executions. Multiple queries or executions may be run concurrently from the returned statement.
Example ¶
Output: foo bar <nil>
func (*DB) Query ¶
Query executes a query that returns rows, typically a SELECT. The params are for any placeholder parameters in the query.
Example ¶
Output: User<1 admin [admin1@admin admin2@admin]> [User<1 admin [admin1@admin admin2@admin]> User<2 root [root1@root root2@root]>] Story<1 Cool story User<1 admin [admin1@admin admin2@admin]>>
func (*DB) QueryOne ¶
QueryOne acts like Query, but query must return only one row. It returns ErrNoRows error when query returns zero rows or ErrMultiRows when query returns multiple rows.
Example ¶
Output: 1 {admin}
Example (Returning_id) ¶
Output: {1 admin}
func (*DB) RunInTransaction ¶
RunInTransaction runs a function in a transaction. If function returns an error transaction is rollbacked, otherwise transaction is committed.
Example ¶
Output: 1
func (*DB) Select ¶
Select selects the model by primary key.
Example ¶
Output: Book<Id=1 Title="book 1">
Example (AllColumns) ¶
Output: Book<Id=1 Title="book 1"> 1
Example (FirstRow) ¶
Output: Book<Id=1 Title="book 1">
Example (GroupBy) ¶
Output: len 2 author 1 has 2 books author 11 has 1 books
Example (LastRow) ¶
Output: Book<Id=3 Title="book 3">
Example (SomeColumns) ¶
Output: Book<Id=1 Title="book 1">
Example (SomeColumnsIntoVars) ¶
Output: 1 book 1
Example (SqlExpression) ¶
Output: [1 2 3]
Example (TableAlias) ¶
Output: Book<Id=1 Title="book 1">
Example (WhereOr) ¶
Output: [Book<Id=1 Title="book 1"> Book<Id=2 Title="book 2">]
func (*DB) Update ¶
Update updates the model by primary key.
Example ¶
Output: Book<Id=1 Title="updated book 1">
Example (SetValues) ¶
Output: Book<Id=1 Title="prefix book 1 suffix">
Example (SomeColumns) ¶
Output: Book<Id=1 Title="updated book 1"> 1
Example (SomeColumns2) ¶
Output: Book<Id=1 Title="updated book 1"> 1
type IntSet ¶
type IntSet map[int64]struct{}
func (*IntSet) NewModel ¶
func (set *IntSet) NewModel() orm.ColumnScanner
type Ints ¶
type Ints []int64
Example ¶
Output: [0 1 2 3 4 5 6 7 8 9 10] <nil>
Example (In) ¶
Output: SELECT * FROM table WHERE id IN (1,2,3)
func (*Ints) NewModel ¶
func (ints *Ints) NewModel() orm.ColumnScanner
type Listener ¶
type Listener struct {
// contains filtered or unexported fields
}
Not thread-safe.
Example ¶
Output: mychan "hello world" <nil>
type Options ¶
type Options struct { // The network type, either tcp or unix. // Default is tcp. Network string // TCP host:port or Unix socket depending on Network. Addr string User string Password string Database string // Whether to use secure TCP/IP connections (TLS). SSL bool // PostgreSQL run-time configuration parameters to be set on connection. Params map[string]interface{} // The maximum number of retries before giving up. // Default is to not retry failed queries. MaxRetries int // The deadline for establishing new connections. If reached, // dial will fail with a timeout. // Default is 5 seconds. DialTimeout time.Duration // The timeout for socket reads. If reached, commands will fail // with a timeout error instead of blocking. // Default is no timeout. ReadTimeout time.Duration // The timeout for socket writes. If reached, commands will fail // with a timeout error instead of blocking. // Default is no timeout. WriteTimeout time.Duration // The maximum number of open socket connections. // Default is 20 connections. PoolSize int // The amount of time client waits for free connection if all // connections are busy before returning an error. // Default is 5 seconds. PoolTimeout time.Duration // The amount of time after which client closes idle connections. // Default is to not close idle connections. IdleTimeout time.Duration // The frequency of idle checks. // Default is 1 minute. IdleCheckFrequency time.Duration }
Database connection options.
type Stmt ¶
type Stmt struct {
// contains filtered or unexported fields
}
Stmt is a prepared statement. Stmt is safe for concurrent use by multiple goroutines.
func (*Stmt) ExecOne ¶
ExecOne acts like Exec, but query must affect only one row. It returns ErrNoRows error when query returns zero rows or ErrMultiRows when query returns multiple rows.
type Strings ¶
type Strings []string
Example ¶
Output: [foo bar] <nil>
func (Strings) AppendValue ¶
func (*Strings) NewModel ¶
func (strings *Strings) NewModel() orm.ColumnScanner
type Tx ¶
type Tx struct {
// contains filtered or unexported fields
}
Tx is an in-progress database transaction.
A transaction must end with a call to Commit or Rollback.
After a call to Commit or Rollback, all operations on the transaction fail with ErrTxDone.
The statements prepared for a transaction by calling the transaction's Prepare or Stmt methods are closed by the call to Commit or Rollback.
func (*Tx) ExecOne ¶
ExecOne acts like Exec, but query must affect only one row. It returns ErrNoRows error when query returns zero rows or ErrMultiRows when query returns multiple rows.
func (*Tx) FormatQuery ¶
func (*Tx) Prepare ¶
Prepare creates a prepared statement for use within a transaction.
The returned statement operates within the transaction and can no longer be used once the transaction has been committed or rolled back.
To use an existing prepared statement on this transaction, see Tx.Stmt.
func (*Tx) Query ¶
func (tx *Tx) Query(model interface{}, query interface{}, params ...interface{}) (*types.Result, error)
Query executes a query with the given parameters in a transaction.
func (*Tx) QueryOne ¶
func (tx *Tx) QueryOne(model interface{}, query interface{}, params ...interface{}) (*types.Result, error)
QueryOne acts like Query, but query must return only one row. It returns ErrNoRows error when query returns zero rows or ErrMultiRows when query returns multiple rows.