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alter_foreign_key.go
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alter_foreign_key.go
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// Copyright 2020-2021 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package plan
import (
"fmt"
"strings"
"gopkg.in/src-d/go-errors.v1"
"github.com/Sndav/go-mysql-server/sql"
)
var (
// ErrNoForeignKeySupport is returned when the table does not support FOREIGN KEY operations.
ErrNoForeignKeySupport = errors.NewKind("the table does not support foreign key operations: %s")
// ErrForeignKeyMissingColumns is returned when an ALTER TABLE ADD FOREIGN KEY statement does not provide any columns
ErrForeignKeyMissingColumns = errors.NewKind("cannot create a foreign key without columns")
// ErrAddForeignKeyDuplicateColumn is returned when an ALTER TABLE ADD FOREIGN KEY statement has the same column multiple times
ErrAddForeignKeyDuplicateColumn = errors.NewKind("cannot have duplicates of columns in a foreign key: `%v`")
// ErrTemporaryTablesForeignKeySupport is returns when a user tries to create a temporary table with a foreign key
ErrTemporaryTablesForeignKeySupport = errors.NewKind("temporary tables do not support foreign keys")
)
type CreateForeignKey struct {
// In the cases where we have multiple ALTER statements, we need to resolve the table at execution time rather than
// during analysis. Otherwise, you could add a column in the preceding alter and we may have analyzed to a table
// that did not yet have that column.
ddlNode
Table string
ReferencedTable string
FkDef *sql.ForeignKeyConstraint
}
var _ sql.Node = (*CreateForeignKey)(nil)
var _ sql.Databaser = (*CreateForeignKey)(nil)
type DropForeignKey struct {
UnaryNode
Name string
}
func NewAlterAddForeignKey(db sql.Database, table, refTable string, fkDef *sql.ForeignKeyConstraint) *CreateForeignKey {
return &CreateForeignKey{
ddlNode: ddlNode{db},
Table: table,
ReferencedTable: refTable,
FkDef: fkDef,
}
}
func NewAlterDropForeignKey(table sql.Node, name string) *DropForeignKey {
return &DropForeignKey{
UnaryNode: UnaryNode{Child: table},
Name: name,
}
}
func getForeignKeyAlterable(node sql.Node) (sql.ForeignKeyAlterableTable, error) {
switch node := node.(type) {
case sql.ForeignKeyAlterableTable:
return node, nil
case *ResolvedTable:
return getForeignKeyAlterableTable(node.Table)
case sql.TableWrapper:
return getForeignKeyAlterableTable(node.Underlying())
}
for _, child := range node.Children() {
n, _ := getForeignKeyAlterable(child)
if n != nil {
return n, nil
}
}
return nil, ErrNoForeignKeySupport.New(node.String())
}
func getForeignKeyAlterableTable(t sql.Table) (sql.ForeignKeyAlterableTable, error) {
switch t := t.(type) {
case sql.ForeignKeyAlterableTable:
return t, nil
case sql.TableWrapper:
return getForeignKeyAlterableTable(t.Underlying())
default:
return nil, ErrNoForeignKeySupport.New(t.Name())
}
}
// Execute inserts the rows in the database.
func (p *CreateForeignKey) Execute(ctx *sql.Context) error {
tbl, ok, err := p.db.GetTableInsensitive(ctx, p.Table)
if err != nil {
return err
}
if !ok {
return sql.ErrTableNotFound.New(p.Table)
}
refTbl, ok, err := p.db.GetTableInsensitive(ctx, p.ReferencedTable)
if err != nil {
return err
}
if !ok {
return sql.ErrTableNotFound.New(p.ReferencedTable)
}
fkAlterable, ok := tbl.(sql.ForeignKeyAlterableTable)
if !ok {
return ErrNoForeignKeySupport.New(p.Table)
}
return executeCreateForeignKey(ctx, fkAlterable, refTbl, p.FkDef)
}
// executeCreateForeignKey verifies the foreign key definition and calls CreateForeignKey on the given table.
func executeCreateForeignKey(ctx *sql.Context, fkAlterable sql.ForeignKeyAlterableTable, refTbl sql.Table, fkDef *sql.ForeignKeyConstraint) error {
if t, ok := fkAlterable.(sql.TemporaryTable); ok && t.IsTemporary() {
return ErrTemporaryTablesForeignKeySupport.New()
}
if len(fkDef.Columns) == 0 {
return ErrForeignKeyMissingColumns.New()
}
if len(fkDef.Columns) != len(fkDef.ReferencedColumns) {
return sql.ErrForeignKeyColumnCountMismatch.New()
}
// Make sure that all columns are valid, in the table, and there are no duplicates
seenCols := make(map[string]bool)
actualColNames := make(map[string]string)
for _, col := range fkAlterable.Schema() {
lowerColName := strings.ToLower(col.Name)
seenCols[lowerColName] = false
actualColNames[lowerColName] = col.Name
}
for i, fkCol := range fkDef.Columns {
lowerFkCol := strings.ToLower(fkCol)
if seen, ok := seenCols[lowerFkCol]; ok {
if !seen {
seenCols[lowerFkCol] = true
fkDef.Columns[i] = actualColNames[lowerFkCol]
} else {
return ErrAddForeignKeyDuplicateColumn.New(fkCol)
}
} else {
return sql.ErrTableColumnNotFound.New(fkAlterable.Name(), fkCol)
}
}
// Do the same for the referenced columns
seenCols = make(map[string]bool)
actualColNames = make(map[string]string)
for _, col := range refTbl.Schema() {
lowerColName := strings.ToLower(col.Name)
seenCols[lowerColName] = false
actualColNames[lowerColName] = col.Name
}
for i, fkRefCol := range fkDef.ReferencedColumns {
lowerFkRefCol := strings.ToLower(fkRefCol)
if seen, ok := seenCols[lowerFkRefCol]; ok {
if !seen {
seenCols[lowerFkRefCol] = true
fkDef.ReferencedColumns[i] = actualColNames[lowerFkRefCol]
} else {
return ErrAddForeignKeyDuplicateColumn.New(fkRefCol)
}
} else {
return sql.ErrTableColumnNotFound.New(fkDef.ReferencedTable, fkRefCol)
}
}
return fkAlterable.CreateForeignKey(ctx, fkDef.Name, fkDef.Columns, fkDef.ReferencedTable, fkDef.ReferencedColumns, fkDef.OnUpdate, fkDef.OnDelete)
}
// WithDatabase implements the sql.Databaser interface.
func (p *CreateForeignKey) WithDatabase(db sql.Database) (sql.Node, error) {
np := *p
np.db = db
return &np, nil
}
// Execute inserts the rows in the database.
func (p *DropForeignKey) Execute(ctx *sql.Context) error {
fkAlterable, err := getForeignKeyAlterable(p.UnaryNode.Child)
if err != nil {
return err
}
return fkAlterable.DropForeignKey(ctx, p.Name)
}
// RowIter implements the Node interface.
func (p *DropForeignKey) RowIter(ctx *sql.Context, row sql.Row) (sql.RowIter, error) {
err := p.Execute(ctx)
if err != nil {
return nil, err
}
return sql.RowsToRowIter(), nil
}
// WithChildren implements the Node interface.
func (p *DropForeignKey) WithChildren(children ...sql.Node) (sql.Node, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(p, len(children), 1)
}
return NewAlterDropForeignKey(children[0], p.Name), nil
}
// WithChildren implements the Node interface.
func (p *CreateForeignKey) WithChildren(children ...sql.Node) (sql.Node, error) {
return NillaryWithChildren(p, children...)
}
func (p *CreateForeignKey) Schema() sql.Schema { return nil }
func (p *DropForeignKey) Schema() sql.Schema { return nil }
func (p *CreateForeignKey) RowIter(ctx *sql.Context, row sql.Row) (sql.RowIter, error) {
err := p.Execute(ctx)
if err != nil {
return nil, err
}
return sql.RowsToRowIter(), nil
}
func (p DropForeignKey) String() string {
pr := sql.NewTreePrinter()
_ = pr.WriteNode("DropForeignKey(%s)", p.Name)
_ = pr.WriteChildren(fmt.Sprintf("Table(%s)", p.UnaryNode.Child.String()))
return pr.String()
}
func (p CreateForeignKey) String() string {
pr := sql.NewTreePrinter()
_ = pr.WriteNode("AddForeignKey(%s)", p.FkDef.Name)
_ = pr.WriteChildren(
fmt.Sprintf("Table(%s)", p.Table),
fmt.Sprintf("Columns(%s)", strings.Join(p.FkDef.Columns, ", ")),
fmt.Sprintf("ReferencedTable(%s)", p.ReferencedTable),
fmt.Sprintf("ReferencedColumns(%s)", strings.Join(p.FkDef.ReferencedColumns, ", ")),
fmt.Sprintf("OnUpdate(%s)", p.FkDef.OnUpdate),
fmt.Sprintf("OnDelete(%s)", p.FkDef.OnDelete))
return pr.String()
}