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schema_builder.go
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/
schema_builder.go
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package migration
import (
"fmt"
"os"
)
type constraint struct {
name string
expr string
operation string
primaryColumns []string
uniqueColumns []string
foreignKey *foreignKey
index *index
}
type index struct {
name string
columns []string
}
type foreignKey struct {
table *Table
columns []string
references string
on string
onDelete string
onUpdate string
}
// Column type is the column definition
type Column struct {
table *Table
name string
dataType *DataType
nullable bool
defaultValue any
unique bool
primary bool
incrementing bool
oldName string
operation string
foreignKeys []*foreignKey
}
// Table type is the table definition
type Table struct {
dialect string
name string
columns []*Column
constraints []*constraint
operation string
}
// Schema type is the schema definition
type Schema struct {
dialect string
tableName string
operation string
table *Table
}
func determineDialect() string {
if dialect := os.Getenv("DB_DRIVER"); dialect != "" {
return dialect
}
// default to sqlite
return "sqlite"
}
// NewSchema creates a new schema based on the dialect provided in the environment variable DB_DRIVER
func NewSchema() *Schema {
return &Schema{dialect: determineDialect()}
}
// Create provides callback to create a new table, and returns a schema
func Create(tableName string, tableFunc func(t *Table)) *Schema {
s := NewSchema()
s.tableName = tableName
s.operation = "create"
t := &Table{name: tableName, dialect: s.dialect}
s.table = t
tableFunc(t)
return s
}
// Alter provides callback to alter an existing table, and returns a schema
func Alter(tableName string, tableFunc func(t *Table)) *Schema {
s := NewSchema()
s.tableName = tableName
s.operation = "alter"
t := &Table{name: tableName, dialect: s.dialect}
s.table = t
tableFunc(t)
return s
}
// Drop returns a schema to drop a table
func Drop(tableName string) *Schema {
s := NewSchema()
s.tableName = tableName
s.operation = "drop"
s.table = &Table{name: tableName, dialect: s.dialect}
return s
}
// HasConstraints returns true if the table has constraints
func (t *Table) HasConstraints() bool {
return len(t.constraints) > 0
}
// Increments adds an auto-incrementing column to the table
func (t *Table) Increments(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeIncrements, t.dialect)).Unsigned()
c.incrementing = true
return c
}
// BigIncrements adds an auto-incrementing column to the table with big integers
func (t *Table) BigIncrements(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeBigIncrements, t.dialect)).Unsigned()
c.incrementing = true
return c
}
// String adds a varchar column to the table
func (t *Table) String(name string, length uint) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeVarchar, t.dialect).WithLength(length))
return c
}
// Text adds a text column to the table
func (t *Table) Text(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeText, t.dialect))
return c
}
// TinyInt adds a tiny integer column to the table
func (t *Table) TinyInt(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeTinyInt, t.dialect))
return c
}
// SmallInt adds a small integer column to the table
func (t *Table) SmallInt(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeSmallInt, t.dialect))
return c
}
// MediumInt adds a medium integer column to the table
func (t *Table) MediumInt(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeMediumInt, t.dialect))
return c
}
// Int adds an integer column to the table
func (t *Table) Int(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeInt, t.dialect))
return c
}
// BigInt adds a big integer column to the table
func (t *Table) BigInt(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeBigInt, t.dialect))
return c
}
// Binary adds a binary column to the table
func (t *Table) Binary(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeBinary, t.dialect))
return c
}
// Boolean adds a boolean column to the table
func (t *Table) Boolean(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeBool, t.dialect))
return c
}
// Char adds a char column to the table
func (t *Table) Char(name string, length uint) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeChar, t.dialect).WithLength(length))
return c
}
// DateTimeTz adds a date time with timezone column to the table
func (t *Table) DateTimeTz(name string, precision uint) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeDateTimeTz, t.dialect).WithPrecision(precision))
return c
}
// DateTime adds a date time column to the table
func (t *Table) DateTime(name string, precision uint) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeDateTime, t.dialect).WithPrecision(precision))
return c
}
// Date adds a date column to the table
func (t *Table) Date(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeDate, t.dialect))
return c
}
// Decimal adds a decimal column to the table
func (t *Table) Decimal(name string, precision uint, scale uint) *Column {
c := t.AddColumn(
name,
NewDataType(name, ColTypeDecimal, t.dialect).
WithPrecision(precision).
WithScale(scale),
)
return c
}
// Double adds a double column to the table
func (t *Table) Double(name string, precision uint, scale uint) *Column {
c := t.AddColumn(
name,
NewDataType(name, ColTypeDouble, t.dialect).
WithPrecision(precision).
WithScale(scale),
)
return c
}
// Enum adds an enum column to the table
func (t *Table) Enum(name string, values ...string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeEnum, t.dialect).WithEnumValues(values))
return c
}
// UnsignedTinyInt adds an unsigned tiny integer column to the table
func (t *Table) UnsignedBigInt(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeBigInt, t.dialect)).Unsigned()
return c
}
// UnsignedInt adds an unsigned integer column to the table
func (t *Table) UnsignedInt(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeInt, t.dialect)).Unsigned()
return c
}
// UnsignedMediumInt adds an unsigned medium integer column to the table
func (t *Table) UnsignedMediumInt(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeMediumInt, t.dialect)).Unsigned()
return c
}
// UnsignedSmallInt adds an unsigned small integer column to the table
func (t *Table) UnsignedSmallInt(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeSmallInt, t.dialect)).Unsigned()
return c
}
// UnsignedTinyInt adds an unsigned tiny integer column to the table
func (t *Table) UnsignedTinyInt(name string) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeTinyInt, t.dialect)).Unsigned()
return c
}
// Float adds a float column to the table
func (t *Table) Float(name string, precision uint, scale uint) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeFloat, t.dialect).WithPrecision(precision).WithScale(scale))
return c
}
// Time adds a time column to the table
func (t *Table) Time(name string, precision uint) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeTime, t.dialect).WithPrecision(precision))
return c
}
// Timestamp adds a timestamp with timezone column to the table
func (t *Table) Timestamp(name string, precision uint) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeTimestamp, t.dialect).WithPrecision(precision))
return c
}
// Timestamp adds a timestamp with timezone column to the table
func (t *Table) TimestampTz(name string, precision uint) *Column {
c := t.AddColumn(name, NewDataType(name, ColTypeTimestampTz, t.dialect).WithPrecision(precision))
return c
}
// AddColumn adds a new column to the table
func (t *Table) AddColumn(name string, dataType *DataType) *Column {
c := &Column{
name: name,
table: t,
dataType: dataType,
operation: "add",
}
t.columns = append(t.columns, c)
return c
}
// DropColumn drops a column from the table
func (t *Table) DropColumn(name string) *Column {
c := &Column{
table: t,
name: name,
operation: "drop",
}
t.columns = append(t.columns, c)
return c
}
// AlterColumn alters a column in the table
func (t *Table) AlterColumn(name string, dataType string) *Column {
c := &Column{
table: t,
name: name,
operation: "alter",
}
t.columns = append(t.columns, c)
return c
}
// RenameColumn renames a column in the table
func (t *Table) RenameColumn(oldName string, newName string) *Column {
c := &Column{
table: t,
name: newName,
oldName: oldName,
operation: "rename",
}
t.columns = append(t.columns, c)
return c
}
// PrimaryKey adds a primary key to the table
func (t *Table) PrimaryKey(columns ...string) {
// panic if there is already a drop operation for primary key
for _, c := range t.constraints {
if c.operation == "drop" && len(c.primaryColumns) > 0 {
panic("cannot add primary key when there is a drop operation for primary key in the table")
}
}
// panic if there is already a primary key
for _, c := range t.constraints {
if c.operation == "add" && len(c.primaryColumns) > 0 {
panic("multiple primary keys are not allowed in a table")
}
}
c := &constraint{
name: t.name + "_pkey",
operation: "add",
primaryColumns: columns,
}
t.constraints = append(t.constraints, c)
}
// DropPrimaryKey drops the primary key from the table
func (t *Table) DropPrimaryKey() {
// panic if there is already an add operation for primary key
for _, c := range t.constraints {
if c.operation == "add" && len(c.primaryColumns) > 0 {
panic("cannot drop primary key when there is an add operation for primary key in the table")
}
}
c := &constraint{
name: t.name + "_pkey",
operation: "drop",
}
t.constraints = append(t.constraints, c)
}
// Index adds an index to the table
func (t *Table) Index(columns ...string) {
indexName := ""
if len(columns) == 1 {
indexName = t.name + "_" + columns[0] + "_index"
} else {
for _, column := range columns {
indexName += column + "_"
}
indexName += "index"
}
c := &constraint{
name: indexName,
operation: "add",
index: &index{
name: indexName,
columns: columns,
},
}
t.constraints = append(t.constraints, c)
}
// DropIndex drops an index from the table
func (t *Table) DropIndex(indexName string) {
c := &constraint{
name: indexName,
operation: "drop",
}
t.constraints = append(t.constraints, c)
}
// UniqueKey adds a unique constraint to the table
func (t *Table) UniqueKey(columns ...string) {
constraintName := t.name + "_"
if len(columns) == 1 {
constraintName = columns[0] + "_unique"
} else {
for _, column := range columns {
constraintName += column + "_"
}
constraintName += "unique"
}
c := &constraint{
name: constraintName,
operation: "add",
uniqueColumns: columns,
}
t.constraints = append(t.constraints, c)
}
// DropUniqueKey drops a unique constraint from the table
func (t *Table) DropUniqueKey(name string) {
c := &constraint{
name: name,
operation: "drop",
}
t.constraints = append(t.constraints, c)
}
// ForeignKey adds a foreign key to the table
func (t *Table) ForeignKey(columns ...string) *foreignKey {
fk := &foreignKey{
table: t,
columns: columns,
}
fkName := ""
for _, column := range columns {
fkName += column + "_"
}
c := &constraint{
name: fkName + "_fkey",
operation: "add",
foreignKey: fk,
}
t.constraints = append(t.constraints, c)
return fk
}
// DropForeignKey drops a foreign key from the table
func (f *foreignKey) References(table string) *foreignKey {
f.references = table
return f
}
// On adds the ON clause to the foreign key
func (f *foreignKey) On(on string) *foreignKey {
f.on = on
return f
}
// OnDelete adds the ON DELETE clause to the foreign key
func (f *foreignKey) OnDelete(onDelete string) *foreignKey {
f.onDelete = onDelete
return f
}
// OnUpdate adds the ON UPDATE clause to the foreign key
func (f *foreignKey) OnUpdate(onUpdate string) *foreignKey {
f.onUpdate = onUpdate
return f
}
// DropForeignKey drops a foreign key from the table
func (t *Table) DropForeignKey(name string) {
c := &constraint{
name: name,
operation: "drop",
}
t.constraints = append(t.constraints, c)
}
// Type adds a data type to the column
func (c *Column) Type(dataType *DataType) *Column {
c.dataType = dataType
return c
}
// Unsigned adds the unsigned attribute to the column
func (c *Column) Unsigned() *Column {
c.dataType.unsigned = true
return c
}
// Nullable adds the nullable attribute to the column
func (c *Column) Nullable() *Column {
c.nullable = true
return c
}
// NotNull adds the not null attribute to the column
func (c *Column) NotNull() *Column {
c.nullable = false
return c
}
// Default adds the default value to the column
func (c *Column) Default(defaultValue any) *Column {
c.defaultValue = defaultValue
return c
}
// Unique adds the unique attribute to the column
func (c *Column) Unique() *Column {
c.unique = true
return c
}
// Primary adds the primary attribute to the column
func (c *Column) Primary() *Column {
c.primary = true
return c
}
// Change changes the operation of the column to alter
func (c *Column) Change() {
c.operation = "alter"
}
// Done returns the table that the column belongs to
func (c *Column) Done() *Table {
return c.table
}
// Build returns the SQL query for the schema
func (s *Schema) Build() string {
switch s.operation {
case "create":
return s.buildCreate()
case "alter":
return s.buildAlter()
case "drop":
return s.buildDrop()
}
return ""
}
func (s *Schema) buildCreate() string {
switch s.dialect {
case DialectSQLite:
return s.buildCreateSQLite()
case DialectMySQL:
return s.buildCreateMySQL()
case DialectPostgres:
return s.buildCreatePostgreSQL()
}
return ""
}
func (s *Schema) buildAlter() string {
switch s.dialect {
case DialectSQLite:
return s.buildAlterSQLite()
case DialectMySQL:
return s.buildAlterMySQL()
case DialectPostgres:
return s.buildAlterPostgreSQL()
}
return ""
}
func (s *Schema) buildDrop() string {
switch s.dialect {
case DialectSQLite:
return s.buildDropSQLite()
case DialectMySQL:
return s.buildDropMySQL()
case DialectPostgres:
return s.buildDropPostgreSQL()
}
return ""
}
func (s *Schema) buildCreateSQLite() string {
sql := "CREATE TABLE " + s.tableName + " ("
for index, column := range s.table.columns {
if index == len(s.table.columns)-1 && !s.table.HasConstraints() {
sql += s.buildColumn(column, false)
} else {
sql += s.buildColumn(column, true)
}
}
sql += s.buildConstraints()
sql += ");"
return sql
}
func (s *Schema) buildCreateMySQL() string {
sql := "CREATE TABLE " + s.tableName + " ("
for index, column := range s.table.columns {
if index == len(s.table.columns)-1 && !s.table.HasConstraints() {
sql += s.buildColumn(column, false)
} else {
sql += s.buildColumn(column, true)
}
}
sql += s.buildConstraints()
sql += ");"
return sql
}
func (s *Schema) buildCreatePostgreSQL() string {
sql := "CREATE TABLE " + s.tableName + " ("
for index, column := range s.table.columns {
if index == len(s.table.columns)-1 && !s.table.HasConstraints() {
sql += s.buildColumn(column, false)
} else {
sql += s.buildColumn(column, true)
}
}
sql += s.buildConstraints()
sql += ");"
return sql
}
func (s *Schema) buildAlterSQLite() string {
sql := "ALTER TABLE " + s.tableName + " "
for index, column := range s.table.columns {
columnStr := ""
if index == len(s.table.columns)-1 {
columnStr = s.buildColumn(column, false)
} else {
columnStr = s.buildColumn(column, true)
}
switch column.operation {
case "add":
sql += "ADD COLUMN " + columnStr
case "drop":
sql += "DROP COLUMN " + column.name
case "alter":
sql += "ALTER COLUMN " + columnStr
case "rename":
sql += "RENAME COLUMN " + column.oldName + " TO " + column.name
}
}
sql += s.buildConstraints()
sql += ";"
return sql
}
func (s *Schema) buildAlterMySQL() string {
sql := "ALTER TABLE " + s.tableName + " "
for index, column := range s.table.columns {
columnStr := ""
if index == len(s.table.columns)-1 {
columnStr = s.buildColumn(column, false)
} else {
columnStr = s.buildColumn(column, true)
}
switch column.operation {
case "add":
sql += "ADD COLUMN " + columnStr
case "drop":
sql += "DROP COLUMN " + column.name
case "alter":
sql += "MODIFY COLUMN " + columnStr
case "rename":
sql += "RENAME COLUMN " + column.oldName + " TO " + column.name
}
}
sql += s.buildConstraints()
sql += ";"
return sql
}
func (s *Schema) buildAlterPostgreSQL() string {
sql := "ALTER TABLE " + s.tableName + " "
for index, column := range s.table.columns {
columnStr := ""
if index == len(s.table.columns)-1 {
columnStr = s.buildColumn(column, false)
} else {
columnStr = s.buildColumn(column, true)
}
switch column.operation {
case "add":
sql += "ADD COLUMN " + columnStr
case "drop":
sql += "DROP COLUMN " + column.name
case "alter":
sql += "ALTER COLUMN " + columnStr
case "rename":
sql += "RENAME COLUMN " + column.oldName + " TO " + column.name
}
}
sql += s.buildConstraints()
sql += ";"
return sql
}
func (s *Schema) buildDropSQLite() string {
return "DROP TABLE " + s.tableName + ";"
}
func (s *Schema) buildDropMySQL() string {
return "DROP TABLE " + s.tableName + ";"
}
func (s *Schema) buildDropPostgreSQL() string {
return "DROP TABLE " + s.tableName + ";"
}
func (s *Schema) buildColumn(column *Column, trailingComma bool) string {
sql := "\n" + column.name + " "
if column.dataType != nil {
sql += column.dataType.ToString()
}
if !column.nullable {
sql += " NOT NULL"
}
if column.defaultValue != nil {
sql += " DEFAULT " + fmt.Sprintf("%v", column.defaultValue)
}
if column.unique {
sql += " UNIQUE"
}
if column.primary {
sql += " PRIMARY KEY"
}
if column.table.dialect == DialectSQLite && column.incrementing {
sql += " AUTOINCREMENT"
}
if column.table.dialect == DialectMySQL && column.incrementing {
sql += " AUTO_INCREMENT"
}
if len(column.foreignKeys) > 0 {
for _, fk := range column.foreignKeys {
sql += ", " + s.buildForeignKey(fk)
}
}
if column.dataType != nil {
sql += column.dataType.suffix
}
// Add trailing comma if trailingComma is true
if trailingComma {
return sql + ", "
}
return sql
}
func (s *Schema) buildConstraints() string {
sql := ""
for _, constraint := range s.table.constraints {
switch constraint.operation {
case "add":
if len(constraint.primaryColumns) > 0 {
sql += "PRIMARY KEY (" + s.buildColumns(constraint.primaryColumns) + "), "
}
if len(constraint.uniqueColumns) > 0 {
prefix := ""
if s.dialect == DialectPostgres {
prefix = "UNIQUE "
} else if s.dialect == DialectMySQL {
prefix = "UNIQUE " + constraint.name + " "
} else if s.dialect == DialectSQLite {
prefix = "UNIQUE "
}
sql += prefix + "(" + s.buildColumns(constraint.uniqueColumns) + "), "
}
if constraint.index != nil {
sql += "INDEX " + constraint.index.name + " (" + s.buildColumns(constraint.index.columns) + "), "
}
if constraint.foreignKey != nil {
sql += s.buildForeignKey(constraint.foreignKey) + ", "
}
case "drop":
if len(constraint.primaryColumns) > 0 {
sql += "DROP PRIMARY KEY, "
}
if len(constraint.uniqueColumns) > 0 {
sql += "DROP UNIQUE (" + s.buildColumns(constraint.uniqueColumns) + "), "
}
if constraint.index != nil {
sql += "DROP INDEX " + constraint.index.name + ", "
}
if constraint.foreignKey != nil {
sql += "DROP FOREIGN KEY " + constraint.name + ", "
}
}
}
// Remove trailing comma if there is any
if len(sql) > 0 {
sql = sql[:len(sql)-2]
}
return sql
}
func (s *Schema) buildForeignKey(fk *foreignKey) string {
sql := "\nFOREIGN KEY (" + s.buildColumns(fk.columns) + ") REFERENCES " + fk.on + "(" + fk.references + ")"
if fk.onDelete != "" {
sql += " ON DELETE " + fk.onDelete
}
if fk.onUpdate != "" {
sql += " ON UPDATE " + fk.onUpdate
}
return sql
}
func (s *Schema) buildColumns(columns []string) string {
sql := ""
for _, column := range columns {
sql += column + ", "
}
return sql[:len(sql)-2]
}
// String returns the SQL query for the schema
func (s *Schema) String() string {
return s.Build()
}