mirror of https://github.com/go-gorm/gorm.git
104 lines
3.4 KiB
Go
104 lines
3.4 KiB
Go
package gorm
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import (
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"database/sql"
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"fmt"
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"reflect"
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"strconv"
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"strings"
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)
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// Dialect interface contains behaviors that differ across SQL database
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type Dialect interface {
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// GetName get dialect's name
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GetName() string
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// SetDB set db for dialect
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SetDB(db *sql.DB)
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// BindVar return the placeholder for actual values in SQL statements, in many dbs it is "?", Postgres using $1
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BindVar(i int) string
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// Quote quotes field name to avoid SQL parsing exceptions by using a reserved word as a field name
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Quote(key string) string
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// DataTypeOf return data's sql type
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DataTypeOf(field *StructField) string
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// HasIndex check has index or not
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HasIndex(tableName string, indexName string) bool
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// HasForeignKey check has foreign key or not
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HasForeignKey(tableName string, foreignKeyName string) bool
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// RemoveIndex remove index
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RemoveIndex(tableName string, indexName string) error
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// HasTable check has table or not
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HasTable(tableName string) bool
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// HasColumn check has column or not
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HasColumn(tableName string, columnName string) bool
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// LimitAndOffsetSQL return generated SQL with Limit and Offset, as mssql has special case
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LimitAndOffsetSQL(limit, offset int) string
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// SelectFromDummyTable return select values, for most dbs, `SELECT values` just works, mysql needs `SELECT value FROM DUAL`
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SelectFromDummyTable() string
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// LastInsertIdReturningSuffix most dbs support LastInsertId, but postgres needs to use `RETURNING`
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LastInsertIDReturningSuffix(tableName, columnName string) string
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// BuildForeignKeyName returns a foreign key name for the given table, field and reference
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BuildForeignKeyName(tableName, field, dest string) string
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}
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var dialectsMap = map[string]Dialect{}
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func newDialect(name string, db *sql.DB) Dialect {
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if value, ok := dialectsMap[name]; ok {
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dialect := reflect.New(reflect.TypeOf(value).Elem()).Interface().(Dialect)
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dialect.SetDB(db)
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return dialect
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}
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fmt.Printf("`%v` is not officially supported, running under compatibility mode.\n", name)
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commontDialect := &commonDialect{}
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commontDialect.SetDB(db)
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return commontDialect
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}
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// RegisterDialect register new dialect
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func RegisterDialect(name string, dialect Dialect) {
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dialectsMap[name] = dialect
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}
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// ParseFieldStructForDialect parse field struct for dialect
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func ParseFieldStructForDialect(field *StructField) (fieldValue reflect.Value, sqlType string, size int, additionalType string) {
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// Get redirected field type
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var reflectType = field.Struct.Type
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for reflectType.Kind() == reflect.Ptr {
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reflectType = reflectType.Elem()
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}
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// Get redirected field value
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fieldValue = reflect.Indirect(reflect.New(reflectType))
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// Get scanner's real value
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var getScannerValue func(reflect.Value)
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getScannerValue = func(value reflect.Value) {
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fieldValue = value
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if _, isScanner := reflect.New(fieldValue.Type()).Interface().(sql.Scanner); isScanner && fieldValue.Kind() == reflect.Struct {
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getScannerValue(fieldValue.Field(0))
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}
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}
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getScannerValue(fieldValue)
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// Default Size
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if num, ok := field.TagSettings["SIZE"]; ok {
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size, _ = strconv.Atoi(num)
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} else {
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size = 255
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}
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// Default type from tag setting
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additionalType = field.TagSettings["NOT NULL"] + " " + field.TagSettings["UNIQUE"]
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if value, ok := field.TagSettings["DEFAULT"]; ok {
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additionalType = additionalType + " DEFAULT " + value
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}
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return fieldValue, field.TagSettings["TYPE"], size, strings.TrimSpace(additionalType)
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}
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