writefreely/db/create.go
2019-12-28 15:15:47 -05:00

244 lines
4.8 KiB
Go

package db
import (
"fmt"
"strings"
)
type ColumnType int
type OptionalInt struct {
Set bool
Value int
}
type OptionalString struct {
Set bool
Value string
}
type SQLBuilder interface {
ToSQL() (string, error)
}
type Column struct {
Dialect DialectType
Name string
Nullable bool
Default OptionalString
Type ColumnType
Size OptionalInt
PrimaryKey bool
}
type CreateTableSqlBuilder struct {
Dialect DialectType
Name string
IfNotExists bool
ColumnOrder []string
Columns map[string]*Column
Constraints []string
}
const (
ColumnTypeBool ColumnType = iota
ColumnTypeSmallInt ColumnType = iota
ColumnTypeInteger ColumnType = iota
ColumnTypeChar ColumnType = iota
ColumnTypeVarChar ColumnType = iota
ColumnTypeText ColumnType = iota
ColumnTypeDateTime ColumnType = iota
)
var _ SQLBuilder = &CreateTableSqlBuilder{}
var UnsetSize OptionalInt = OptionalInt{Set: false, Value: 0}
var UnsetDefault OptionalString = OptionalString{Set: false, Value: ""}
func (d ColumnType) Format(dialect DialectType, size OptionalInt) (string, error) {
if dialect != DialectMySQL && dialect != DialectSQLite {
return "", fmt.Errorf("unsupported column type %d for dialect %d and size %v", d, dialect, size)
}
switch d {
case ColumnTypeSmallInt:
{
if dialect == DialectSQLite {
return "INTEGER", nil
}
mod := ""
if size.Set {
mod = fmt.Sprintf("(%d)", size.Value)
}
return "SMALLINT" + mod, nil
}
case ColumnTypeInteger:
{
if dialect == DialectSQLite {
return "INTEGER", nil
}
mod := ""
if size.Set {
mod = fmt.Sprintf("(%d)", size.Value)
}
return "INT" + mod, nil
}
case ColumnTypeChar:
{
if dialect == DialectSQLite {
return "TEXT", nil
}
mod := ""
if size.Set {
mod = fmt.Sprintf("(%d)", size.Value)
}
return "CHAR" + mod, nil
}
case ColumnTypeVarChar:
{
if dialect == DialectSQLite {
return "TEXT", nil
}
mod := ""
if size.Set {
mod = fmt.Sprintf("(%d)", size.Value)
}
return "VARCHAR" + mod, nil
}
case ColumnTypeBool:
{
if dialect == DialectSQLite {
return "INTEGER", nil
}
return "TINYINT(1)", nil
}
case ColumnTypeDateTime:
return "DATETIME", nil
case ColumnTypeText:
return "TEXT", nil
}
return "", fmt.Errorf("unsupported column type %d for dialect %d and size %v", d, dialect, size)
}
func (c *Column) SetName(name string) *Column {
c.Name = name
return c
}
func (c *Column) SetNullable(nullable bool) *Column {
c.Nullable = nullable
return c
}
func (c *Column) SetPrimaryKey(pk bool) *Column {
c.PrimaryKey = pk
return c
}
func (c *Column) SetDefault(value string) *Column {
c.Default = OptionalString{Set: true, Value: value}
return c
}
func (c *Column) SetType(t ColumnType) *Column {
c.Type = t
return c
}
func (c *Column) SetSize(size int) *Column {
c.Size = OptionalInt{Set: true, Value: size}
return c
}
func (c *Column) String() (string, error) {
var str strings.Builder
str.WriteString(c.Name)
str.WriteString(" ")
typeStr, err := c.Type.Format(c.Dialect, c.Size)
if err != nil {
return "", err
}
str.WriteString(typeStr)
if !c.Nullable {
str.WriteString(" NOT NULL")
}
if c.Default.Set {
str.WriteString(" DEFAULT ")
str.WriteString(c.Default.Value)
}
if c.PrimaryKey {
str.WriteString(" PRIMARY KEY")
}
return str.String(), nil
}
func (b *CreateTableSqlBuilder) Column(column *Column) *CreateTableSqlBuilder {
if b.Columns == nil {
b.Columns = make(map[string]*Column)
}
b.Columns[column.Name] = column
b.ColumnOrder = append(b.ColumnOrder, column.Name)
return b
}
func (b *CreateTableSqlBuilder) UniqueConstraint(columns ...string) *CreateTableSqlBuilder {
for _, column := range columns {
if _, ok := b.Columns[column]; !ok {
// This fails silently.
return b
}
}
b.Constraints = append(b.Constraints, fmt.Sprintf("UNIQUE(%s)", strings.Join(columns, ",")))
return b
}
func (b *CreateTableSqlBuilder) SetIfNotExists(ine bool) *CreateTableSqlBuilder {
b.IfNotExists = ine
return b
}
func (b *CreateTableSqlBuilder) ToSQL() (string, error) {
var str strings.Builder
str.WriteString("CREATE TABLE ")
if b.IfNotExists {
str.WriteString("IF NOT EXISTS ")
}
str.WriteString(b.Name)
var things []string
for _, columnName := range b.ColumnOrder {
column, ok := b.Columns[columnName]
if !ok {
return "", fmt.Errorf("column not found: %s", columnName)
}
columnStr, err := column.String()
if err != nil {
return "", err
}
things = append(things, columnStr)
}
for _, constraint := range b.Constraints {
things = append(things, constraint)
}
if thingLen := len(things); thingLen > 0 {
str.WriteString(" ( ")
for i, thing := range things {
str.WriteString(thing)
if i < thingLen-1 {
str.WriteString(", ")
}
}
str.WriteString(" )")
}
return str.String(), nil
}