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constraints.go
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constraints.go
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// Copyright 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 analyzer
import (
"strings"
"github.com/gabereiser/go-mysql-server/sql/transform"
"github.com/gabereiser/go-mysql-server/sql"
"github.com/gabereiser/go-mysql-server/sql/plan"
)
// resolveDropConstraint replaces DropConstraint nodes with a concrete type of alter table node as appropriate, or
// throws a constraint not found error if the named constraint isn't found on the table given.
func resolveDropConstraint(ctx *sql.Context, a *Analyzer, n sql.Node, scope *Scope, sel RuleSelector) (sql.Node, transform.TreeIdentity, error) {
dropConstraint, ok := n.(*plan.DropConstraint)
if !ok {
return n, transform.SameTree, nil
}
rt, ok := dropConstraint.Child.(*plan.ResolvedTable)
if !ok {
return nil, transform.SameTree, ErrInAnalysis.New("Expected a ResolvedTable for ALTER TABLE DROP CONSTRAINT statement")
}
//TODO: handle if a foreign key and check constraint have the same name, it should error saying to use the specific drop
table := rt.Table
fkt, ok := table.(sql.ForeignKeyTable)
if ok {
decFks, err := fkt.GetDeclaredForeignKeys(ctx)
if err != nil {
return nil, transform.SameTree, err
}
refFks, err := fkt.GetReferencedForeignKeys(ctx)
if err != nil {
return nil, transform.SameTree, err
}
for _, fk := range append(decFks, refFks...) {
if strings.ToLower(fk.Name) == strings.ToLower(dropConstraint.Name) {
n, err = plan.NewAlterDropForeignKey(rt.Database.Name(), rt.Table.Name(), dropConstraint.Name).
WithDatabaseProvider(a.Catalog.Provider)
return n, transform.NewTree, err
}
}
}
ct, ok := table.(sql.CheckTable)
if ok {
checks, err := ct.GetChecks(ctx)
if err != nil {
return nil, transform.SameTree, err
}
for _, check := range checks {
if strings.ToLower(check.Name) == strings.ToLower(dropConstraint.Name) {
return plan.NewAlterDropCheck(rt, check.Name), transform.NewTree, nil
}
}
}
return nil, transform.SameTree, sql.ErrUnknownConstraint.New(dropConstraint.Name)
}
// validateDropConstraint returns an error if the constraint named to be dropped doesn't exist
func validateDropConstraint(ctx *sql.Context, a *Analyzer, n sql.Node, scope *Scope, sel RuleSelector) (sql.Node, transform.TreeIdentity, error) {
switch n := n.(type) {
case *plan.DropCheck:
rt, ok := n.Child.(*plan.ResolvedTable)
if !ok {
return nil, transform.SameTree, ErrInAnalysis.New("Expected a ResolvedTable for ALTER TABLE DROP CONSTRAINT statement")
}
ct, ok := rt.Table.(sql.CheckTable)
if ok {
checks, err := ct.GetChecks(ctx)
if err != nil {
return nil, transform.SameTree, err
}
for _, check := range checks {
if strings.ToLower(check.Name) == strings.ToLower(n.Name) {
return n, transform.SameTree, nil
}
}
return nil, transform.SameTree, sql.ErrUnknownConstraint.New(n.Name)
}
return nil, transform.SameTree, plan.ErrNoCheckConstraintSupport.New(rt.Table.Name())
default:
return n, transform.SameTree, nil
}
}