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schema.go
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schema.go
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// Copyright 2021-present The Atlas Authors. All rights reserved.
// This source code is licensed under the Apache 2.0 license found
// in the LICENSE file in the root directory of this source tree.
package schema
type (
// A Realm or a database describes a domain of schema resources that are logically connected
// and can be accessed and queried in the same connection (e.g. a physical database instance).
Realm struct {
Schemas []*Schema
Attrs []Attr
}
// A Schema describes a database schema (i.e. named database).
Schema struct {
Name string
Realm *Realm
Tables []*Table
Attrs []Attr // Attrs and options.
}
// A Table represents a table definition.
Table struct {
Name string
Schema *Schema
Columns []*Column
Indexes []*Index
PrimaryKey *Index
ForeignKeys []*ForeignKey
Attrs []Attr // Attrs, constraints and options.
}
// A Column represents a column definition.
Column struct {
Name string
Type *ColumnType
Default Expr
Attrs []Attr
Indexes []*Index
// Foreign keys that this column is
// part of their child columns.
ForeignKeys []*ForeignKey
}
// ColumnType represents a column type that is implemented by the dialect.
ColumnType struct {
Type Type
Raw string
Null bool
}
// An Index represents an index definition.
Index struct {
Name string
Unique bool
Table *Table
Attrs []Attr
Parts []*IndexPart
}
// An IndexPart represents an index part that
// can be either an expression or a column.
IndexPart struct {
// SeqNo represents the sequence number of the key part
// in the index.
SeqNo int
// Desc indicates if the key part is stored in descending
// order. All databases use ascending order as default.
Desc bool
X Expr
C *Column
Attrs []Attr
}
// A ForeignKey represents an index definition.
ForeignKey struct {
Symbol string
Table *Table
Columns []*Column
RefTable *Table
RefColumns []*Column
OnUpdate ReferenceOption
OnDelete ReferenceOption
}
)
// Schema returns the first schema that matched the given name.
func (r *Realm) Schema(name string) (*Schema, bool) {
for _, t := range r.Schemas {
if t.Name == name {
return t, true
}
}
return nil, false
}
// Table returns the first table that matched the given name.
func (s *Schema) Table(name string) (*Table, bool) {
for _, t := range s.Tables {
if t.Name == name {
return t, true
}
}
return nil, false
}
// Column returns the first column that matched the given name.
func (t *Table) Column(name string) (*Column, bool) {
for _, c := range t.Columns {
if c.Name == name {
return c, true
}
}
return nil, false
}
// Index returns the first index that matched the given name.
func (t *Table) Index(name string) (*Index, bool) {
for _, i := range t.Indexes {
if i.Name == name {
return i, true
}
}
return nil, false
}
// ForeignKey returns the first foreign-key that matched the given symbol (constraint name).
func (t *Table) ForeignKey(symbol string) (*ForeignKey, bool) {
for _, f := range t.ForeignKeys {
if f.Symbol == symbol {
return f, true
}
}
return nil, false
}
// Column returns the first column that matches the given name.
func (f *ForeignKey) Column(name string) (*Column, bool) {
for _, c := range f.Columns {
if c.Name == name {
return c, true
}
}
return nil, false
}
// RefColumn returns the first referenced column that matches the given name.
func (f *ForeignKey) RefColumn(name string) (*Column, bool) {
for _, c := range f.RefColumns {
if c.Name == name {
return c, true
}
}
return nil, false
}
// ReferenceOption for constraint actions.
type ReferenceOption string
// Reference options (actions) specified by ON UPDATE and ON DELETE
// subclauses of the FOREIGN KEY clause.
const (
NoAction ReferenceOption = "NO ACTION"
Restrict ReferenceOption = "RESTRICT"
Cascade ReferenceOption = "CASCADE"
SetNull ReferenceOption = "SET NULL"
SetDefault ReferenceOption = "SET DEFAULT"
)
type (
// A Type represents a database type. The types below implements this
// interface and can be used for describing schemas.
//
// The Type interface can also be implemented outside this package as follows:
//
// type SpatialType struct {
// schema.Type
// T string
// }
//
// var t schema.Type = &SpatialType{T: "point"}
//
Type interface {
typ()
}
// EnumType represents an enum type.
EnumType struct {
T string // Optional type.
Values []string // Enum values.
}
// BinaryType represents a type that stores a binary data.
BinaryType struct {
T string
Size int
}
// StringType represents a string type.
StringType struct {
T string
Size int
}
// BoolType represents a boolean type.
BoolType struct {
T string
}
// IntegerType represents an int type.
IntegerType struct {
T string
Unsigned bool
Attrs []Attr
}
// DecimalType represents a fixed-point type that stores exact numeric values.
DecimalType struct {
T string
Precision int
Scale int
Unsigned bool
}
// FloatType represents a floating-point type that stores approximate numeric values.
FloatType struct {
T string
Unsigned bool
Precision int
}
// TimeType represents a date/time type.
TimeType struct {
T string
Precision *int
}
// JSONType represents a JSON type.
JSONType struct {
T string
}
// SpatialType represents a spatial/geometric type.
SpatialType struct {
T string
}
// UnsupportedType represents a type that is not supported by the drivers.
UnsupportedType struct {
T string
}
)
type (
// Expr defines an SQL expression in schema DDL.
Expr interface {
expr()
}
// Literal represents a basic literal expression like 1, or '1'.
// String literals are usually quoted with single or double quotes.
Literal struct {
V string
}
// RawExpr represents a raw expression like "uuid()" or "current_timestamp()".
// Unlike literals, raw expression are usually inlined as is on migration.
RawExpr struct {
X string
}
)
type (
// Attr represents the interface that all attributes implement.
Attr interface {
attr()
}
// Comment describes a schema element comment.
Comment struct {
Text string
}
// Charset describes a column or a table character-set setting.
Charset struct {
V string
}
// Collation describes a column or a table collation setting.
Collation struct {
V string
}
// Check describes a CHECK constraint.
Check struct {
Name string // Optional constraint name.
Expr string // Actual CHECK.
Attrs []Attr // Additional attributes (e.g. ENFORCED).
}
// GeneratedExpr describes the expression used for generating
// the value of a generated/virtual column.
GeneratedExpr struct {
Expr string
Type string // Optional type. e.g. STORED or VIRTUAL.
}
)
// expressions.
func (*Literal) expr() {}
func (*RawExpr) expr() {}
// types.
func (*BoolType) typ() {}
func (*EnumType) typ() {}
func (*TimeType) typ() {}
func (*JSONType) typ() {}
func (*FloatType) typ() {}
func (*StringType) typ() {}
func (*BinaryType) typ() {}
func (*SpatialType) typ() {}
func (*IntegerType) typ() {}
func (*DecimalType) typ() {}
func (*UnsupportedType) typ() {}
// attributes.
func (*Check) attr() {}
func (*Comment) attr() {}
func (*Charset) attr() {}
func (*Collation) attr() {}
func (*GeneratedExpr) attr() {}