jinzhu/gorm

package gorm

import (
    "encoding/json"
    "fmt"
    "reflect"
    "strings"
    "time"
)

type postgres struct {
    commonDialect
}

func init() {
    RegisterDialect("postgres", &postgres{})
    RegisterDialect("cloudsqlpostgres", &postgres{})
}

func (postgres) GetName() string {
    return "postgres"
}

func (postgres) BindVar(i int) string {
    return fmt.Sprintf("$%v", i)
}

func (s *postgres) DataTypeOf(field *StructField) string {
    var dataValue, sqlType, size, additionalType = ParseFieldStructForDialect(field, s)

    if sqlType == "" {
        switch dataValue.Kind() {
        case reflect.Bool:
            sqlType = "boolean"
        case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uintptr:
            if s.fieldCanAutoIncrement(field) {
                field.TagSettingsSet("AUTO_INCREMENT", "AUTO_INCREMENT")
                sqlType = "serial"
            } else {
                sqlType = "integer"
            }
        case reflect.Int64, reflect.Uint32, reflect.Uint64:
            if s.fieldCanAutoIncrement(field) {
                field.TagSettingsSet("AUTO_INCREMENT", "AUTO_INCREMENT")
                sqlType = "bigserial"
            } else {
                sqlType = "bigint"
            }
        case reflect.Float32, reflect.Float64:
            sqlType = "numeric"
        case reflect.String:
            if _, ok := field.TagSettingsGet("SIZE"); !ok {
                size = 0 // if SIZE haven't been set, use `text` as the default type, as there are no performance different
            }

            if size > 0 && size < 65532 {
                sqlType = fmt.Sprintf("varchar(%d)", size)
            } else {
                sqlType = "text"
            }
        case reflect.Struct:
            if _, ok := dataValue.Interface().(time.Time); ok {
                sqlType = "timestamp with time zone"
            }
        case reflect.Map:
            if dataValue.Type().Name() == "Hstore" {
                sqlType = "hstore"
            }
        default:
            if IsByteArrayOrSlice(dataValue) {
                sqlType = "bytea"

                if isUUID(dataValue) {
                    sqlType = "uuid"
                }

                if isJSON(dataValue) {
                    sqlType = "jsonb"
                }
            }
        }
    }

    if sqlType == "" {
        panic(fmt.Sprintf("invalid sql type %s (%s) for postgres", dataValue.Type().Name(), dataValue.Kind().String()))
    }

    if strings.TrimSpace(additionalType) == "" {
        return sqlType
    }
    return fmt.Sprintf("%v %v", sqlType, additionalType)
}

func (s postgres) HasIndex(tableName string, indexName string) bool {
    var count int
    s.db.QueryRow("SELECT count(*) FROM pg_indexes WHERE tablename = $1 AND indexname = $2 AND schemaname = CURRENT_SCHEMA()", tableName, indexName).Scan(&count)
    return count > 0
}

func (s postgres) HasForeignKey(tableName string, foreignKeyName string) bool {
    var count int
    s.db.QueryRow("SELECT count(con.conname) FROM pg_constraint con WHERE $1::regclass::oid = con.conrelid AND con.conname = $2 AND con.contype='f'", tableName, foreignKeyName).Scan(&count)
    return count > 0
}

func (s postgres) HasTable(tableName string) bool {
    var count int
    s.db.QueryRow("SELECT count(*) FROM INFORMATION_SCHEMA.tables WHERE table_name = $1 AND table_type = 'BASE TABLE' AND table_schema = CURRENT_SCHEMA()", tableName).Scan(&count)
    return count > 0
}

func (s postgres) HasColumn(tableName string, columnName string) bool {
    var count int
    s.db.QueryRow("SELECT count(*) FROM INFORMATION_SCHEMA.columns WHERE table_name = $1 AND column_name = $2 AND table_schema = CURRENT_SCHEMA()", tableName, columnName).Scan(&count)
    return count > 0
}

func (s postgres) CurrentDatabase() (name string) {
    s.db.QueryRow("SELECT CURRENT_DATABASE()").Scan(&name)
    return
}

func (s postgres) LastInsertIDOutputInterstitial(tableName, key string, columns []string) string {
    return ""
}

func (s postgres) LastInsertIDReturningSuffix(tableName, key string) string {
    return fmt.Sprintf("RETURNING %v.%v", tableName, key)
}

func (postgres) SupportLastInsertID() bool {
    return false
}

func isUUID(value reflect.Value) bool {
    if value.Kind() != reflect.Array || value.Type().Len() != 16 {
        return false
    }
    typename := value.Type().Name()
    lower := strings.ToLower(typename)
    return "uuid" == lower || "guid" == lower
}

func isJSON(value reflect.Value) bool {
    _, ok := value.Interface().(json.RawMessage)
    return ok
}