64 lines
1.5 KiB
Go
64 lines
1.5 KiB
Go
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package ddl
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import (
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"bytes"
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"database/sql/driver"
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"encoding/binary"
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"fmt"
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)
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// Location is a database type that stores a geographic
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// point on the earth with a longitude and latitude.
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// It can currently only used for Mariadb!
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type Location struct {
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Longitude float64
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Latitude float64
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}
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// Scan handles the scanning of the custom location type
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// for a MariaDb datbase
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func (g *Location) Scan(src interface{}) error {
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switch src.(type) {
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case []byte:
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var b = src.([]byte)
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if len(b) != 25 {
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return fmt.Errorf("expected []bytes with length 25, got %d", len(b))
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}
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var longitude float64
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var latitude float64
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buf := bytes.NewReader(b[9:17])
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err := binary.Read(buf, binary.LittleEndian, &longitude)
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if err != nil {
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return err
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}
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buf = bytes.NewReader(b[17:25])
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err = binary.Read(buf, binary.LittleEndian, &latitude)
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if err != nil {
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return err
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}
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*g = Location{longitude, latitude}
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default:
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return fmt.Errorf("expected []byte for Location type, got %T", src)
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}
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return nil
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}
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// Value transforms the latitude and longitude into the
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// "WKB" format the database understands.
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// See https://dev.mysql.com/doc/refman/8.0/en/gis-data-formats.html
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func (g Location) Value() (driver.Value, error) {
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buf := new(bytes.Buffer)
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// Padding
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binary.Write(buf, binary.LittleEndian, []byte{0, 0, 0, 0})
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// Point
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binary.Write(buf, binary.LittleEndian, []byte{1, 1, 0, 0, 0})
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// Data
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binary.Write(buf, binary.LittleEndian, g.Longitude)
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binary.Write(buf, binary.LittleEndian, g.Latitude)
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return buf.Bytes(), nil
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}
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