pg-structure / M2ORelation

# Class: M2ORelation

Class which represent many to one relationship which resembles belongsTo relation in ORMs (Object Relational Mappers). Provides attributes and methods for details of the relationship.

Actually there is no many to one relation in database engine. It is basically one to many relation in reverse direction.

Below is a database schema as an example:

Some definitions used in descriptions for M2ORelation.

** Source Table: ** Table which this relationship belongs to.
** Target Table: ** Table that is related to base table.

# Example

// Example tables have single primary key and examples first relation. So zero index ([0]) is used. Use all array elements if necessary.
// line_item >---- product
// (source)        (target)

const relation     = line_item.m2oRelations[0];            // RELATION:    line_item >---- product
const foreignKey   = relation.foreignKey;                  // CONSTRAINT:               ^-- product_has_carts
const sourceTable  = relation.sourceTable;                 // TABLE:       line_item
const targetTable  = relation.targetTable;                 // TABLE:       product
const FKColumn     = relation.foreignKey.columns[0];       // COLUMN:      product_id  (from line_item table)
const PKColumn     = relation.targetTable.primaryKeys[0];  // COLUMN:      id          (from product table)

# Hierarchy

Relation

↳ M2ORelation

# Properties

# foreignKey

• foreignKey: ForeignKey

Foreign key between source table and target table.

# Example

const relation     = product.M2ORelationRelations[0];  // RELATION:    line_item >---- product
const foreignKey   = relation.foreignKey;              // CONSTRAINT:               ^-- product_has_carts
const FKColumn     = relation.foreignKey.columns[0];   // COLUMN:      product_id (from line_item table)

Defined in: pg-structure/relation/m2o-relation.ts:118

# toMany

• Readonly toMany: boolean= false

Whether the relation targets to many. Since, many to one relations targets single, this is true.

Defined in: pg-structure/relation/m2o-relation.ts:55

# type

• Readonly type: M2O

Type of the relation, which is m2o for M2ORelation. For TypeScript it is enum of RelationType.M2O.

Defined in: pg-structure/relation/m2o-relation.ts:50

# Accessors

# info

• get info(): string

Informational text representation of the relation.

# Example

const info = relation.info; // [public.cart] ⭃―― cart_contact ―――[public.contact]

Returns: string

Defined in: pg-structure/relation/m2o-relation.ts:84

# name

• get name(): string

Suggested name for relation.

see {@link ../relation-names.md Relation Names}

Returns: string

Defined in: pg-structure/relation/m2o-relation.ts:63

# sourceAdjective

• get sourceAdjective(): undefined | string

Source table's adjective extracted from foreign key name.

Returns: undefined | string

Defined in: pg-structure/base/relation.ts:86

# sourceAlias

• get sourceAlias(): string

Source table alias

Returns: string

Defined in: pg-structure/relation/m2o-relation.ts:141

# sourceName

• get sourceName(): string

Source table name.

Returns: string

Defined in: pg-structure/base/relation.ts:76

# sourceTable

• get sourceTable(): Table

Table which this relation belongs to.

# Example

const relation     = product.M2ORelationRelations[0];  // RELATION:    line_item >---- product
const sourceTable  = relation.sourceTable;             // TABLE:       line_item

Returns: Table

Defined in: pg-structure/relation/m2o-relation.ts:95

# targetAdjective

• get targetAdjective(): undefined | string

Source table's adjective extracted from foreign key name.

Returns: undefined | string

Defined in: pg-structure/base/relation.ts:91

# targetAlias

• get targetAlias(): string

Target table alias

Returns: string

Defined in: pg-structure/relation/m2o-relation.ts:146

# targetName

• get targetName(): string

Target table name

Returns: string

Defined in: pg-structure/base/relation.ts:81

# targetTable

• get targetTable(): Table

Table which this relation is referred by.

# Example

const relation     = product.M2ORelationRelations[0];  // RELATION:    line_item >---- product
const targetTable  = relation.targetTable;             // TABLE:       product

Returns: Table

Defined in: pg-structure/relation/m2o-relation.ts:106

# Methods

# getName

▸ getName(relationNameFunctions: string | RelationNameFunctions): string

Returns name for the relation using given naming function.

# Parameters:

Name	Type	Description
`relationNameFunctions`	string \| RelationNameFunctions	are custom functions or name of the module that exports relation name functions to generate names with. `pg-structure` provides some builtin modules (`short`, `optimal` and `descriptive`), but you can use your own.

Returns: string

name for the relation using naming function.

Defined in: pg-structure/relation/m2o-relation.ts:74

# getSourceAliasWithout

▸ getSourceAliasWithout(without: any | source | target | RelationWithout[]): string

Returns source table alias after replacing given tables' names from it.

# Parameters:

Name	Type	Description
`without`	any \| source \| target \| RelationWithout[]	is type or types of tables to exclude names of.

Returns: string

source table alias after given tables' names replaced.

Defined in: pg-structure/relation/m2o-relation.ts:126

# getSourceNameWithout

▸ getSourceNameWithout(without: any | source | target | RelationWithout[]): string

Returns source table name after replacing given tables' names from it.

# Parameters:

Name	Type	Description
`without`	any \| source \| target \| RelationWithout[]	is type or types of tables to exclude names of.

Returns: string

source table name after given tables' names replaced.

Inherited from: Relation

Defined in: pg-structure/base/relation.ts:61

# getTargetAliasWithout

▸ getTargetAliasWithout(without: any | source | target | RelationWithout[]): string

Returns target table alias after replacing given tables' names from it.

# Parameters:

Name	Type	Description
`without`	any \| source \| target \| RelationWithout[]	is type or types of tables to exclude names of.

Returns: string

target table alias after given tables' names replaced.

Defined in: pg-structure/relation/m2o-relation.ts:136

# getTargetNameWithout

▸ getTargetNameWithout(without: any | source | target | RelationWithout[]): string

Returns target table name after replacing given tables' names from it.

# Parameters:

Name	Type	Description
`without`	any \| source \| target \| RelationWithout[]	is type or types of tables to exclude names of.

Returns: string

target table name after given tables' names replaced.

Inherited from: Relation

Defined in: pg-structure/base/relation.ts:71

← M2MRelation MaterializedView →