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migration.go
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migration.go
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package generator
import (
"bytes"
"encoding"
"encoding/json"
"fmt"
"strings"
)
// Migration contains all the data to represent a schema migration.
type Migration struct {
// Up contains the changes to update from the previous version to the current one.
Up ChangeSet
// Down contains all the changes to downgrade to the previous version.
Down ChangeSet
// Lock contains the locked model schema.
Lock *DBSchema
}
// NewMigration creates a new migration from the old and the new schema.
func NewMigration(old, new *DBSchema) (*Migration, error) {
var (
migration = &Migration{}
err error
oldTables = old.index()
newTables = new.index()
)
migration.Up, err = SchemaDiff(old, new).
sorted(oldTables, newTables)
if err != nil {
return nil, err
}
migration.Down, err = migration.Up.
ReverseChangeSet(old).
sorted(newTables, oldTables)
if err != nil {
return nil, err
}
migration.Lock = new
return migration, nil
}
// DBSchema represents a schema of all the models in the database.
type DBSchema struct {
// Tables are the schema of all the tables.
Tables []*TableSchema
}
// SchemaFromPackages returns a schema for the given packages models.
func SchemaFromPackages(pkgs ...*Package) (*DBSchema, error) {
t := newPackageTransformer()
return t.transform(pkgs...)
}
func (s *DBSchema) MarshalText() ([]byte, error) {
schema := struct {
Tables []*TableSchema
}{s.Tables}
return json.MarshalIndent(schema, "", " ")
}
// Table finds a table with the given name.
func (s *DBSchema) Table(name string) *TableSchema {
for _, t := range s.Tables {
if t.Name == name {
return t
}
}
return nil
}
func (s *DBSchema) index() map[string]*TableSchema {
var result = make(map[string]*TableSchema)
for _, t := range s.Tables {
result[t.Name] = t
}
return result
}
// TableSchema represents the SQL schema of a table.
type TableSchema struct {
// Name is the table name.
Name string
// Columns are the schemas of the columns in the table.
Columns []*ColumnSchema
}
type relationship struct {
name string
inverse bool
}
func (s *TableSchema) relationships() []relationship {
var rels = make(map[string]struct{})
var result []relationship
for _, c := range s.Columns {
if c.Reference != nil {
if _, ok := rels[c.Reference.Table]; !ok {
result = append(result, relationship{c.Reference.Table, c.Reference.inverse})
rels[c.Reference.Table] = struct{}{}
}
}
}
return result
}
func (s *TableSchema) String() string {
var buf bytes.Buffer
buf.WriteString(fmt.Sprintf("CREATE TABLE %s (\n", s.Name))
for i, c := range s.Columns {
buf.WriteRune('\t')
buf.WriteString(c.String())
if i < len(s.Columns)-1 {
buf.WriteString(",\n")
} else {
buf.WriteRune('\n')
}
}
buf.WriteString(");\n\n")
return buf.String()
}
// Columns returns the schema of the column with the given name.
func (s *TableSchema) Column(name string) *ColumnSchema {
for _, c := range s.Columns {
if c.Name == name {
return c
}
}
return nil
}
func (s *TableSchema) Equals(s2 *TableSchema) bool {
if s.Name != s2.Name || len(s.Columns) != len(s2.Columns) {
return false
}
for i, c := range s.Columns {
if !c.Equals(s2.Columns[i]) {
return false
}
}
return true
}
// ColumnSchema represents the schema of a column.
type ColumnSchema struct {
// Name of the column.
Name string
// Type of the column.
Type ColumnType
// PrimaryKey reports whether the column is a primary key.
PrimaryKey bool
// Reference is an optional reference to another table column.
// If it's not nil, it means this column has a foreign key.
Reference *Reference
// NotNull reports whether the column is not nullable.
NotNull bool
}
func (s *ColumnSchema) Equals(s2 *ColumnSchema) bool {
return s.Name == s2.Name &&
s.Type == s2.Type &&
s.PrimaryKey == s2.PrimaryKey &&
s.NotNull == s2.NotNull &&
s.Reference.Equals(s2.Reference)
}
func (s *ColumnSchema) String() string {
var buf bytes.Buffer
buf.WriteString(s.Name)
buf.WriteRune(' ')
buf.WriteString(string(s.Type))
if s.NotNull {
buf.WriteString(" NOT NULL")
}
if s.PrimaryKey {
buf.WriteString(" PRIMARY KEY")
}
if s.Reference != nil {
buf.WriteString(" REFERENCES ")
buf.WriteString(s.Reference.String())
}
return buf.String()
}
// ColumnType represents the SQL column type.
type ColumnType string
const (
SmallIntColumn ColumnType = "smallint"
IntegerColumn ColumnType = "integer"
BigIntColumn ColumnType = "bigint"
RealColumn ColumnType = "real"
DoubleColumn ColumnType = "double precision"
SmallSerialColumn ColumnType = "smallserial"
SerialColumn ColumnType = "serial"
BigSerialColumn ColumnType = "bigserial"
TimestamptzColumn ColumnType = "timestamptz"
TextColumn ColumnType = "text"
JSONBColumn ColumnType = "jsonb"
BooleanColumn ColumnType = "boolean"
UUIDColumn ColumnType = "uuid"
)
func NumericColumn(precision int) ColumnType {
return ColumnType(fmt.Sprintf("numeric(%d)", precision))
}
func DecimalColumn(precision, scale int) ColumnType {
return ColumnType(fmt.Sprintf("decimal(%d, %d)", precision, scale))
}
func ArrayColumn(typ ColumnType) ColumnType {
// only allow arrays, not matrixes
if strings.HasSuffix(string(typ), "[]") {
return typ
}
return typ + "[]"
}
// Reference represents a reference to another table column.
type Reference struct {
// Table is the referenced table.
Table string
// Column is the referenced column.
Column string
inverse bool
}
func (r *Reference) Equals(r2 *Reference) bool {
if r == nil && r2 == nil {
return true
} else if r == nil || r2 == nil {
return false
}
return r.Table == r2.Table &&
r.Column == r2.Column
}
func (r *Reference) String() string {
return fmt.Sprintf("%s(%s)", r.Table, r.Column)
}
// ChangeSet is a set of changes to be made in a migration.
type ChangeSet []Change
// sorted sorts the given changeset with the given order:
// - first the create tables ordered by their relationships. For example,
// if profiles depends on
// users, users will be created first, and then profiles.
// - second the drop tables, ordered in reverse order by their relationships.
// For example, if profiles depends on users, profiles will be removed first
// and then users.
// - Finally, rest of the changes.
// dropIndex and createIndex are indexes of table name to table schema
// used to look for dependencies of changes in drops and creates respectively.
func (cs ChangeSet) sorted(dropIndex, createIndex map[string]*TableSchema) (ChangeSet, error) {
var (
createTables = make(map[string]Change)
dropTables = make(map[string]Change)
createGraph = newGraph()
dropGraph = newGraph()
others ChangeSet
result ChangeSet
)
for _, c := range cs {
switch c := c.(type) {
case *CreateTable:
createTables[c.Name] = c
if rels := createIndex[c.Name].relationships(); len(rels) > 0 {
for _, r := range rels {
if r.name == c.Name {
continue
}
if r.inverse {
createGraph.dependsOn(c.Name, r.name)
} else {
createGraph.dependsOn(r.name, c.Name)
}
}
} else {
createGraph.add(c.Name)
}
case *DropTable:
dropTables[c.Name] = c
if rels := dropIndex[c.Name].relationships(); len(rels) > 0 {
for _, r := range rels {
if r.name == c.Name {
continue
}
if r.inverse {
dropGraph.dependsOn(c.Name, r.name)
} else {
dropGraph.dependsOn(r.name, c.Name)
}
}
} else {
dropGraph.add(c.Name)
}
default:
others = append(others, c)
}
}
creates, err := createGraph.resolve()
if err != nil {
return nil, err
}
for _, c := range creates {
if change, ok := createTables[c]; ok {
result = append(result, change)
}
}
drops, err := dropGraph.resolve()
if err != nil {
return nil, err
}
drops = reverse(drops)
for _, d := range drops {
if change, ok := dropTables[d]; ok {
result = append(result, change)
}
}
result = append(result, others...)
return result, nil
}
func (cs ChangeSet) MarshalText() ([]byte, error) {
var buf bytes.Buffer
buf.WriteString("BEGIN;\n\n")
for _, c := range cs {
bytes, err := c.MarshalText()
if err != nil {
return nil, err
}
buf.Write(bytes)
buf.WriteRune('\n')
}
buf.WriteString("COMMIT;\n")
return buf.Bytes(), nil
}
func (cs ChangeSet) String() string {
var buf bytes.Buffer
for _, c := range cs {
buf.WriteString(fmt.Sprintf("- %s", c))
}
return buf.String()
}
// Reverse returns the change that will revert the current change set.
func (cs ChangeSet) Reverse(old *DBSchema) Change {
var result = make(ChangeSet, len(cs))
for i, c := range cs {
result[i] = c.Reverse(old)
}
return result
}
// ReverseChangeSet returns the reverse change set of the current one.
func (cs ChangeSet) ReverseChangeSet(old *DBSchema) ChangeSet {
return cs.Reverse(old).(ChangeSet)
}
// Change represents a change to be made in a migration.
type Change interface {
encoding.TextMarshaler
fmt.Stringer
// Reverse returns the change that will revert the current change.
Reverse(old *DBSchema) Change
}
// CreateTable is a change that will add a new table.
type CreateTable struct {
*TableSchema
}
func (c *CreateTable) Reverse(old *DBSchema) Change {
return &DropTable{Name: c.Name}
}
func (c *CreateTable) MarshalText() ([]byte, error) {
return []byte(c.TableSchema.String()), nil
}
func (c *CreateTable) String() string {
var cols = make([]string, len(c.Columns))
for i, c := range c.Columns {
cols[i] = c.Name
}
return fmt.Sprintf("A new table %q has been added with the following columns: %s.", c.Name, strings.Join(cols, ", "))
}
// DropTable is a change that will drop a table.
type DropTable struct {
// Name is the name of the table to drop.
Name string
}
func (c *DropTable) Reverse(old *DBSchema) Change {
return &CreateTable{old.Table(c.Name)}
}
func (c *DropTable) MarshalText() ([]byte, error) {
return []byte(fmt.Sprintf("DROP TABLE %s;\n", c.Name)), nil
}
func (c *DropTable) String() string {
return fmt.Sprintf("Table %q has been deleted, and it will be dropped.", c.Name)
}
// AddColumn is a change that will add a column.
type AddColumn struct {
// Column schema.
Column *ColumnSchema
// Table to add the column to.
Table string
}
func (c *AddColumn) Reverse(old *DBSchema) Change {
return &DropColumn{
Table: c.Table,
Name: c.Column.Name,
}
}
func (c *AddColumn) String() string {
return fmt.Sprintf("A new column %q of type %q has been added to table %q.", c.Column.Name, c.Column.Type, c.Table)
}
func (c *AddColumn) MarshalText() ([]byte, error) {
return []byte(fmt.Sprintf("ALTER TABLE %s ADD COLUMN %s;\n", c.Table, c.Column)), nil
}
// DropColumn is a change that will drop a column.
type DropColumn struct {
// Name of the column.
Name string
// Table name.
Table string
}
func (c *DropColumn) Reverse(old *DBSchema) Change {
return &AddColumn{
Table: c.Table,
Column: old.Table(c.Table).Column(c.Name),
}
}
func (c *DropColumn) String() string {
return fmt.Sprintf("The column %q of table %q has been removed and it will be dropped.", c.Name, c.Table)
}
func (c *DropColumn) MarshalText() ([]byte, error) {
return []byte(fmt.Sprintf("ALTER TABLE %s DROP COLUMN %s;\n", c.Table, c.Name)), nil
}
// ManualChange is a change that cannot be made automatically and requires
// the user to write a proper migration.
type ManualChange struct {
Msg string
}
func (c *ManualChange) Reverse(old *DBSchema) Change {
return c
}
func (c *ManualChange) String() string {
return fmt.Sprintf("A manual change is required: %s.", c.Msg)
}
func (c *ManualChange) MarshalText() ([]byte, error) {
return []byte(fmt.Sprintf("+++ THIS REQUIRES MANUAL MIGRATION: %s +++\n", c.Msg)), nil
}
type graph struct {
nodeList []string
nodes map[string]*node
}
type resolutionCtx struct {
resolved map[string]struct{}
unresolved map[string]struct{}
names []string
}
func newGraph() *graph {
return &graph{nil, make(map[string]*node)}
}
// add adds a new root node that has no dependencies.
func (g *graph) add(name string) *graph {
if _, ok := g.nodes[name]; !ok {
g.nodeList = append(g.nodeList, name)
g.nodes[name] = newNode(name)
}
return g
}
func (g *graph) dependsOn(dependant, dependency string) *graph {
g.node(dependency).addDependant(g.node(dependant))
g.node(dependant).addDependency(g.node(dependency))
return g
}
func (g *graph) node(name string) *node {
g.add(name)
return g.nodes[name]
}
func (g *graph) resolve() ([]string, error) {
ctx := &resolutionCtx{
make(map[string]struct{}),
make(map[string]struct{}),
nil,
}
for _, n := range g.nodeList {
node := g.nodes[n]
if len(node.dependencies) == 0 {
if err := g.nodes[n].resolve(ctx); err != nil {
return nil, err
}
}
}
if len(g.nodes) != len(ctx.names) {
return nil, fmt.Errorf("kallax: unable to resolve all the table dependencies. There is probably a circular dependency somewhere.")
}
return ctx.names, nil
}
type node struct {
name string
dependants []*node
dependencies []*node
}
func newNode(name string) *node {
return &node{name, nil, nil}
}
func (n *node) addDependant(node *node) {
n.dependants = append(n.dependants, node)
}
func (n *node) addDependency(node *node) {
n.dependencies = append(n.dependencies, node)
}
func (n *node) resolve(ctx *resolutionCtx) error {
ctx.unresolved[n.name] = struct{}{}
for _, dep := range n.dependants {
if _, ok := ctx.resolved[dep.name]; !ok {
if _, ok := ctx.unresolved[dep.name]; ok {
return fmt.Errorf("kallax: there is a circular dependency between %s and %s", n.name, dep.name)
}
if err := dep.resolve(ctx); err != nil {
return err
}
}
}
delete(ctx.unresolved, n.name)
ctx.resolved[n.name] = struct{}{}
ctx.names = append(ctx.names, n.name)
return nil
}
// SchemaDiff generates a change set with the diff between two schemas.
func SchemaDiff(old, new *DBSchema) ChangeSet {
var cs ChangeSet
for _, oldTable := range old.Tables {
if t := new.Table(oldTable.Name); t == nil {
cs = append(cs, &DropTable{Name: oldTable.Name})
} else {
cs = append(cs, TableSchemaDiff(oldTable, t)...)
}
}
for _, newTable := range new.Tables {
if t := old.Table(newTable.Name); t == nil {
cs = append(cs, &CreateTable{newTable})
}
}
return cs
}
// TableSchemaDiff generates a change set with the diff between two table
// schemas.
func TableSchemaDiff(old, new *TableSchema) ChangeSet {
var cs ChangeSet
for _, oldCol := range old.Columns {
if c := new.Column(oldCol.Name); c == nil {
cs = append(cs, &DropColumn{
Table: old.Name,
Name: oldCol.Name,
})
} else {
cs = append(cs, ColumnSchemaDiff(old.Name, oldCol, c)...)
}
}
for _, newCol := range new.Columns {
if c := old.Column(newCol.Name); c == nil {
cs = append(cs, &AddColumn{
Table: new.Name,
Column: newCol,
})
}
}
return cs
}
// ColumnSchemaDiff generates the change set with the diff between two column
// schemas.
func ColumnSchemaDiff(table string, old, new *ColumnSchema) ChangeSet {
var cs ChangeSet
if old.Type != new.Type {
cs = append(cs, &ManualChange{
fmt.Sprintf("don't know how to generate migration for a change of type in %s(%s)", table, new.Name),
})
}
if old.PrimaryKey != new.PrimaryKey {
cs = append(cs, &ManualChange{
fmt.Sprintf("don't know how to generate migration for a change of primary key in %s(%s)", table, new.Name),
})
}
if old.NotNull != new.NotNull {
cs = append(cs, &ManualChange{
fmt.Sprintf("don't know how to generate migration for a change of null/not null in %s(%s)", table, new.Name),
})
}
if referenceChanged(old, new) {
cs = append(cs, &ManualChange{
fmt.Sprintf("don't know how to generate migration for a change of foreign key in %s(%s)", table, new.Name),
})
}
return cs
}
func referenceChanged(old, new *ColumnSchema) bool {
return old.Reference != new.Reference &&
(old.Reference == nil ||
new.Reference == nil ||
old.Reference.Column != new.Reference.Column ||
old.Reference.Table != new.Reference.Table)
}
type packageTransformer struct {
// pkg is the current package being transformed.
pkg *Package
// schema is the final schema being built.
schema *DBSchema
tables map[string]*TableSchema
// tableIndex is a map from a Go type to a table name
tableIndex map[string]string
// pkIndex is a map from a table name to its primary key
pkIndex map[string]*Field
// fks keeps all fks indexed by type name
// so they can be added later.
fks map[string][]*ColumnSchema
}
func newPackageTransformer() *packageTransformer {
return &packageTransformer{
schema: new(DBSchema),
tables: make(map[string]*TableSchema),
tableIndex: make(map[string]string),
pkIndex: make(map[string]*Field),
fks: make(map[string][]*ColumnSchema),
}
}
func (t *packageTransformer) transform(pkgs ...*Package) (*DBSchema, error) {
for _, pkg := range pkgs {
for _, m := range pkg.Models {
t.tableIndex[m.Node.String()] = m.Table
t.pkIndex[m.Table] = m.ID
}
}
for _, pkg := range pkgs {
t.pkg = pkg
if err := t.transformPkg(pkg); err != nil {
return nil, err
}
}
if err := t.applyForeignKeys(); err != nil {
return nil, err
}
return t.schema, nil
}
func (t *packageTransformer) applyForeignKeys() error {
for typ, fks := range t.fks {
table, ok := t.tableIndex[typ]
if !ok {
return fmt.Errorf("kallax: unable to find a table for model %s. Is the model package on the input for this command?", typ)
}
schema := t.tables[table]
for _, fk := range fks {
if col := schema.Column(fk.Name); col != nil {
if !col.Equals(fk) {
return fmt.Errorf("kallax: there is an inverse definition conflicting with the column definition of column %s in the table %s. Please, make sure both definitions match.", fk.Name, table)
}
} else {
schema.Columns = append(schema.Columns, fk)
}
}
}
return nil
}
func (t *packageTransformer) transformPkg(pkg *Package) error {
for _, m := range pkg.Models {
table, err := t.transformModel(m)
if err != nil {
return err
}
if prevTable, ok := t.tables[m.Table]; ok && !prevTable.Equals(table) {
return fmt.Errorf("kallax: found more than one model for table %s", m.Table)
}
t.schema.Tables = append(t.schema.Tables, table)
t.tables[table.Name] = table
}
return nil
}
func (t *packageTransformer) transformModel(m *Model) (*TableSchema, error) {
schema := &TableSchema{Name: m.Table}
var columns = make(map[string]*ColumnSchema)
var err error
schema.Columns, err = t.transformFields(m.Fields, columns)
if err != nil {
return nil, err
}
return schema, nil
}
func (t *packageTransformer) transformFields(fields []*Field, columns map[string]*ColumnSchema) ([]*ColumnSchema, error) {
var result []*ColumnSchema
for _, f := range fields {
if f.IsEmbedded {
cols, err := t.transformFields(f.Fields, columns)
if err != nil {
return nil, err
}
result = append(result, cols...)
} else {
column, err := t.transformField(f)
if err != nil {
return nil, err
}
if f.Kind == Relationship && !f.IsInverse() {
typ := removeTypePrefix(f.Type)
t.fks[typ] = append(t.fks[typ], column)
} else if col, ok := columns[f.ColumnName()]; ok {
if !col.Equals(column) {
return nil, fmt.Errorf("kallax: there are two conflicting definitions for column %s on table %s: \n- %s\n- %s", col.Name, f.Model.Table, col, column)
}
// if it's the same column we can skip it
} else {
result = append(result, column)
columns[column.Name] = column
}
}
}
return result, nil
}
func (t *packageTransformer) transformField(f *Field) (*ColumnSchema, error) {
typ, err := t.transformType(f, f.IsPrimaryKey())
if err != nil {
return nil, err
}
ref, err := t.transformRef(f)
if err != nil {
return nil, err
}
name := f.ColumnName()
if f.Kind == Relationship {
name = f.ForeignKey()
}
return &ColumnSchema{
Name: name,
PrimaryKey: f.IsPrimaryKey(),
NotNull: false,
Type: typ,
Reference: ref,
}, nil
}
func (t *packageTransformer) transformType(f *Field, pk bool) (ColumnType, error) {
if typ := f.SQLType(); typ != "" {
return ColumnType(typ), nil
}
if f.IsJSON {
return JSONBColumn, nil
}
if f.Kind == Array || f.Kind == Slice {
return ArrayColumn(typeMappings[removeTypePrefix(f.Type)]), nil
}
if pk {
if !isValidIdentifier(f) {
return ColumnType(""), fmt.Errorf("kallax: type %s is not a valid type for a primary key. On field %s of model %s.", f.Type, f.Name, f.Model.Name)
}
return idTypeMappings[identifierType(f)], nil
}
if f.Kind == Basic {
typ, ok := typeMappings[f.Type]
if !ok {
return ColumnType(""), fmt.Errorf("kallax: type %s can not be converted to a SQL type. On field %s of model %s. Consider using the struct tag `sqltype` to set a custom type for this column.", f.Type, f.Name, f.Model.Name)
}
return typ, nil
}
if f.Kind == Relationship && f.IsInverse() {
typ := removeTypePrefix(f.Type)
table, ok := t.tableIndex[typ]
if !ok {
return ColumnType(""), fmt.Errorf("kallax: unable to find table for type %s in field %s of model %s. Is the model type part of the generation input?", typ, f.Name, f.Model.Name)
}
return t.transformType(t.pkIndex[table], false)
}
if f.Kind == Relationship {
return t.transformType(f.Model.ID, false)
}
if f.Kind == Interface {
typ := removeTypePrefix(typeName(f.Node.Type()))
if typ, ok := typeMappings[typ]; ok {
return typ, nil
}
}
return ColumnType(""), fmt.Errorf("kallax: cannot find a suitable type (%s) for field %s of model %s. Consider using the struct tag `sqltype` to set a custom type for this column.", f.Type, f.Name, f.Model.Name)
}
func (t *packageTransformer) transformRef(f *Field) (*Reference, error) {
if f.Kind == Relationship && f.IsInverse() {
typ := removeTypePrefix(f.Type)
table, ok := t.tableIndex[typ]
if !ok {
return nil, fmt.Errorf("kallax: unable to find table for type %s in field %s of model %s. Is the model type part of the generation input?", typ, f.Name, f.Model.Name)
}
return &Reference{Table: table, Column: t.pkIndex[table].ColumnName(), inverse: true}, nil
} else if f.Kind == Relationship {
return &Reference{Table: f.Model.Table, Column: f.Model.ID.ColumnName(), inverse: false}, nil
}
return nil, nil
}
var typeMappings = map[string]ColumnType{
"gopkg.in/src-d/go-kallax.v1.ULID": UUIDColumn,
"gopkg.in/src-d/go-kallax.v1.UUID": UUIDColumn,
"gopkg.in/src-d/go-kallax.v1.NumericID": BigIntColumn,
"github.com/satori/go.uuid.UUID": UUIDColumn,
"string": TextColumn,
"rune": ColumnType("char(1)"),
"uint8": SmallIntColumn,
"int8": SmallIntColumn,
"byte": SmallIntColumn,
"uint16": IntegerColumn,
"int16": SmallIntColumn,
"uint32": BigIntColumn,
"int32": IntegerColumn,
"uint": NumericColumn(20),
"int": BigIntColumn,
"int64": BigIntColumn,
"uint64": NumericColumn(20),
"float32": RealColumn,
"float64": DoubleColumn,
"bool": BooleanColumn,
"url.URL": TextColumn,
"time.Time": TimestamptzColumn,
"time.Duration": BigIntColumn,
}
var idTypeMappings = map[string]ColumnType{
"kallax.ULID": UUIDColumn,
"kallax.UUID": UUIDColumn,
"kallax.NumericID": SerialColumn,
}
func reverse(slice []string) []string {
result := make([]string, len(slice))
len := len(slice)
for i := len - 1; i >= 0; i-- {
result[i] = slice[len-1-i]
}
return result
}