Relations API Reference

The github.com/forgego/forge/schema package provides expressive constructors for declaring relational links between models.

Relation Types

Forge supports three relational cardinality patterns:

Establishes a foreign key column on the model pointing to a target model's primary key:

schema.ForeignKey("author_id", "User", schema.CascadeCASCADE).
    RelatedName("posts").
    RelatedQueryName("post")

Establishes a foreign key with an automatic UNIQUE database constraint, guaranteeing a strict 1:1 relationship:

schema.OneToOne("profile_id", "UserProfile", schema.CascadeCASCADE).
    RelatedName("user")

Establishes an M:N association across an intermediary through table:

schema.ManyToMany("tags", "Tag").
    Through("post_tags").
    RelatedName("posts")

The CascadeType parameter defines what happens to dependent rows when a referenced record is deleted:

Cascade Type	Behavior	Best Use Case
`schema.CascadeCASCADE`	Recursively deletes dependent rows.	Child line items, sub-components, order items.
`schema.CascadePROTECT`	Blocks deletion and raises an integrity error if dependents exist.	Orders referencing a customer, invoices referencing a company.
`schema.CascadeSET_NULL`	Sets the foreign key column to `NULL`. Requires nullable field.	Optional associations like assigning a support ticket to an agent.
`schema.CascadeSET_DEFAULT`	Sets the foreign key column to its SQL default value.	Reassigning orphaned content to a default system account.
`schema.CascadeDO_NOTHING`	Takes no database action.	Advanced databases with custom database-level trigger scripts.

RelatedName(name string): Sets the reverse accessor name on the target model (e.g. user.Posts).
RelatedQueryName(name string): Sets the query lookup name for reverse filters.
Through(tableName string): Specifies the junction table for ManyToMany relationships.
DBConstraint(bool): If false, omits the foreign key constraint from migrations while maintaining ORM JOIN capabilities.