forked from opengaussexamples/examples
127 lines
3.0 KiB
Go
127 lines
3.0 KiB
Go
package main
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import (
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"context"
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"database/sql"
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"fmt"
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"gitee.com/chentanyang/ogx"
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"gitee.com/chentanyang/ogx/dialect/ogdialect"
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"gitee.com/chentanyang/ogx/extra/ogxdebug"
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_ "gitee.com/opengauss/openGauss-connector-go-pq"
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)
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type Order struct {
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ID int64 `ogx:",pk,autoincrement"`
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// Order and Item in join:Order=Item are fields in OrderToItem model
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Items []Item `ogx:"m2m:order_to_items,join:Order=Item"`
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}
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type Item struct {
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ID int64 `ogx:",pk,autoincrement"`
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// Order and Item in join:Order=Item are fields in OrderToItem model
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Orders []Order `ogx:"m2m:order_to_items,join:Item=Order"`
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}
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type OrderToItem struct {
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OrderID int64 `ogx:",pk"`
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Order *Order `ogx:"rel:belongs-to,join:order_id=id"`
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ItemID int64 `ogx:",pk"`
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Item *Item `ogx:"rel:belongs-to,join:item_id=id"`
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}
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func main() {
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ctx := context.Background()
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connStr := "host=192.168.20.40 port=26000 user=cuih password=Gauss@123 dbname=test sslmode=disable"
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opengaussdb, err := sql.Open("opengauss", connStr)
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if err != nil {
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panic(err)
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}
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db := ogx.NewDB(opengaussdb, ogdialect.New())
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defer db.Close()
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db.AddQueryHook(ogxdebug.NewQueryHook(ogxdebug.WithVerbose(true)))
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// Register many to many model so ogx can better recognize m2m relation.
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// This should be done before you use the model for the first time.
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db.RegisterModel((*OrderToItem)(nil))
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if err := createSchema(ctx, db, (*Order)(nil), (*Item)(nil), (*OrderToItem)(nil)); err != nil {
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panic(err)
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}
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defer func() {
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_ = dropSchema(ctx, db, (*Item)(nil), (*Order)(nil), (*Item)(nil), (*OrderToItem)(nil))
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}()
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order := new(Order)
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if err := db.NewSelect().
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Model(order).
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Relation("Items").
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Order("order.id ASC").
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Limit(1).
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Scan(ctx); err != nil {
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panic(err)
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}
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fmt.Println("Order", order.ID, "Items", order.Items[0].ID, order.Items[1].ID)
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fmt.Println()
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order = new(Order)
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if err := db.NewSelect().
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Model(order).
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Relation("Items", func(q *ogx.SelectQuery) *ogx.SelectQuery {
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q = q.OrderExpr("item.id DESC")
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return q
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}).
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Limit(1).
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Scan(ctx); err != nil {
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panic(err)
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}
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fmt.Println("Order", order.ID, "Items", order.Items[0].ID, order.Items[1].ID)
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fmt.Println()
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item := new(Item)
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if err := db.NewSelect().
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Model(item).
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Relation("Orders").
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Order("item.id ASC").
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Limit(1).
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Scan(ctx); err != nil {
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panic(err)
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}
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fmt.Println("Item", item.ID, "Order", item.Orders[0].ID)
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}
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func createSchema(ctx context.Context, db *ogx.DB, models ...interface{}) error {
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for _, model := range models {
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if _, err := db.NewCreateTable().Model(model).Exec(ctx); err != nil {
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return err
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}
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}
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values := []interface{}{
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&Item{ID: 1},
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&Item{ID: 2},
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&Order{ID: 1},
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&OrderToItem{OrderID: 1, ItemID: 1},
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&OrderToItem{OrderID: 1, ItemID: 2},
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}
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for _, value := range values {
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if _, err := db.NewInsert().Model(value).Exec(ctx); err != nil {
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return err
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}
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}
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return nil
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}
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func dropSchema(ctx context.Context, db *ogx.DB, models ...interface{}) error {
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for _, model := range models {
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if _, err := db.NewDropTable().Model(model).IfExists().Cascade().Exec(ctx); err != nil {
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return err
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}
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}
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return nil
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}
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