sqlchemy

A lightweight golang ORM library inspired by python sqlalchemy.

Features

Automatic creation and synchronization of table schema based on golang struct
Query syntax inpired by sqlalchemy
Support: MySQL/MariaDB with InnoDB engine / Sqlite (Exprimental) / ClickHouse / Dameng (Exprimental)
Support select, insert, update and insertOrupdate (no delete)

Quick Examples

Database initialization

Before using sqlchemy, database connection should be setup first.

Setup database of default backend(MySQL with InnoDB)

dbconn := sql.Open("mysql", "testgo:openstack@tcp(127.0.0.1:3306)/testgo?charset=utf8&parseTime")

sqlchemy.SetDefaultDB(dbconn)

Setup database of MySQL with InnoDB explicitly

dbconn := sql.Open("mysql", "testgo:openstack@tcp(127.0.0.1:3306)/testgo?charset=utf8&parseTime")

sqlchemy.SetDBWithNameBackend(dbconn, sqlchemy.DBName("mysqldb"), sqlchemy.MySQLBackend)

Setup database of SQLite

dbconn := sql.Open("sqlite3", "file:mydb.s3db?cache=shared&mode=rwc")

sqlchemy.SetDBWithNameBackend(dbconn, sqlchemy.DBName("sqlitedb"), sqlchemy.SQLiteBackend)

Setup database of ClickHouse

dbconn := sql.Open("clickhouse", "tcp://host1:9000?username=user&password=qwerty&database=clicks")

sqlchemy.SetDBWithNameBackend(dbconn, sqlchemy.DBName("clickhousedb"), sqlchemy.ClickhouseBackend)

Setup database of Dameng

dbconn := sql.Open("dm", "dm://username:password@host1:5246/schema")

sqlchemy.SetDBWithNameBackend(dbconn, sqlchemy.DBName("damengdb"), sqlchemy.DamengBackend)

Table Schema

Table schema is defined by struct field tags

type TestTable struct {
    Id        string               `primary:"true" width:"128" charset:"ascii" nullable:"false"`
    Name      string               `width:"64" charset:"utf8" index:"true"`
    Gender    string               `width:"10" charset:"ascii"`
    Age       uint8                `default:"18"`
    Info      jsonutils.JSONObject `nullable:"false"`
    Compond   *SCompondStruct      `width:1024`
    CreatedAt time.Time            `nullable:"false" created_at:"true"`
    UpdatedAt time.Time            `nullable:"false" updated_at:"true"`
    Version   int                  `default:"0" nullable:"false" auto_version:"true"`
    DeletedAt time.Time            ``
    Deleted   bool                 `nullable:"false" default:"false"`
    Notes     string               `default:"default notes"`
}

Table initialization

Create a table from a struct schema

tablespec := sqlchemy.NewTableSpecFromStruct(TestTable{}, "testtable")

tablespec := sqlchemy.NewTableSpecFromStructWithDBName(TestTable{}, "testtable", sqlchemy.DBName("mydb"))

Check whether table schema definition is consistent with schema in database.

if !tablespec.CheckSync() {
    log.Fatalf("table not in sync")
}

Synchronize database table schema and make it consistent with the struct defintion.

err := tablespec.Sync()
if err != nil {
    log.Fataf("synchronize table schema failed: %s", er)
}

Query

Construct query

ti := tablespec.Instance()

// select * from testtable
q := ti.Query()

// select * from testtable where id = '981b10ed-b6f9-4120-8a77-a3b03e343143'
// query by field name, in which the name is unique in the query
q := ti.Query().Equals("id", "981b10ed-b6f9-4120-8a77-a3b03e343143")

// query by field instance, in which the field name might be ambiguous
q := ti.Query().Filter(sqlchemy.Equals(ti.Field("id"), "981b10ed-b6f9-4120-8a77-a3b03e343143"))

// joint query

// select * from t1 join t2 on t1.id=t2.testtable_id where t2.created_at > '2019-11-02'
q := ti.Query("name").Join(t2, sqlchemy.Equals(ti.Field("id"), t2.Field("testtable_id"))).Filter(sqlchermy.GT(t2.Field("created_at"), '2019-11-02')

// union query
// select id, name from testtable where id = '981b10ed-b6f9-4120-8a77-a3b03e343143' union select id, name from testtable where id='6fcc87ca-c1da-40ab-849a-305ff2663901'
q1 := t1.Query("id", "name").Equals("id", "981b10ed-b6f9-4120-8a77-a3b03e343143")
q2 := t1.Query("id", "name").Equals("id", "6fcc87ca-c1da-40ab-849a-305ff2663901")
qu := sqlchemy.Union(q1, q2)

Fetch data

q := ti.Query().Equals("id", "e2bc9b659cec407590dc2f3fcb009acb")

// fetch single row into object
row := TestTable{}
err := q.First(&row)
if err != nil {
    log.Fatalf("fetch object error %s", err)
}

// fetch single row into a string map, where strMap is map[string]string
strMap, err := q.FirstStringMap()
if err != nil {
    log.Fatalf("fetch object error %s", err)
}

q := ti.Query().Startswith("id", "abc")
// fetch rows
rows := make([]TestTable, 0)
err := q.All(&rows)
if err != nil {
    log.Fatalf("query failure: %s", err)
}

// fetch rows into string maps, where maps is []map[string]string
maps, err := q.AllStringMap()
if err != nil {
    log.Fatalf("query failure: %s", err)
}

SubQuery

Query can be used as a subquery in other queries.

// derive a subquery from an ordinary query
subq := t1.Query("id").Equals("version", "v2.0").SubQuery()
// use subquery
q := t1.Query().In("id", subq)

Insert

// hook to initialize data field before insert
func (t *TestTable) BeforeInsert() {
    t.Id = uuid4()
}
// initialize data struct
dt1 := TestTable{
    Name: "Test",
}
// insert the data, primary key fields must be populated
// the primary key has been populated by the BeforeInsert hook
err = tablespec.Insert(&dt1)

// insert or update
// insert the object if no primary key conflict, otherwise, update the record
err = tablespec.InsertOrUpdate(&dt1)

Update

// update the field
_, err = tablespec.Update(&dt3, func() error {
    dt3.Name = "New name 4"
    dt3.Compond = &SCompondStruct{Id: "998822333", Age: 80}
    return nil
})

Please refer to sqltest/main.go for more examples.