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5f0d5f4255
pgtype.Row() was optimized for a single line use without much ceremony at a cost of OID registration, which is cumbersome. In practice it so much incovnenience to create new Composite just before making a query. So now there is just a Composite type and 2 helper methods: - SetFields sets composite fields to values passed. This assignment fails if types passed are not assignable to Values pgtype is made of. - Scan acts exactly like query.Scan, but for a composite value. Passed values are set to values from SQL composite.
56 lines
1.3 KiB
Go
56 lines
1.3 KiB
Go
package pgtype_test
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import (
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"context"
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"fmt"
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"os"
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"github.com/jackc/pgtype"
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pgx "github.com/jackc/pgx/v4"
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)
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//ExampleComposite demonstrates use of Row() function to pass and receive
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// back composite types without creating boilderplate custom types.
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func Example_composite() {
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conn, err := pgx.Connect(context.Background(), os.Getenv("PGX_TEST_DATABASE"))
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E(err)
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defer conn.Close(context.Background())
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_, err = conn.Exec(context.Background(), `drop type if exists mytype;
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create type mytype as (
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a int4,
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b text
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);`)
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E(err)
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defer conn.Exec(context.Background(), "drop type mytype")
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var isNull bool
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var a int
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var b *string
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c := pgtype.NewComposite(&pgtype.Int4{}, &pgtype.Text{})
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c.SetFields(2, "bar")
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err = conn.QueryRow(context.Background(), "select $1::mytype", c).
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Scan(c.Scan(&isNull, &a, &b))
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E(err)
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fmt.Printf("First: isNull=%v a=%d b=%s\n", isNull, a, *b)
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err = conn.QueryRow(context.Background(), "select (1, NULL)::mytype").Scan(c.Scan(&isNull, &a, &b))
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E(err)
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fmt.Printf("Second: isNull=%v a=%d b=%v\n", isNull, a, b)
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err = conn.QueryRow(context.Background(), "select NULL::mytype").Scan(c.Scan(&isNull, &a, &b))
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E(err)
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fmt.Printf("Third: isNull=%v\n", isNull)
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// Output:
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// First: isNull=false a=2 b=bar
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// Second: isNull=false a=1 b=<nil>
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// Third: isNull=true
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}
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