diff options
Diffstat (limited to 'vendor/github.com/uptrace/bun/schema/relation.go')
| -rw-r--r-- | vendor/github.com/uptrace/bun/schema/relation.go | 51 |
1 files changed, 45 insertions, 6 deletions
diff --git a/vendor/github.com/uptrace/bun/schema/relation.go b/vendor/github.com/uptrace/bun/schema/relation.go index f653cd7a3..0711635f5 100644 --- a/vendor/github.com/uptrace/bun/schema/relation.go +++ b/vendor/github.com/uptrace/bun/schema/relation.go @@ -13,12 +13,12 @@ const ( ) type Relation struct { + Type int + Field *Field // Has the bun tag defining this relation. + // Base and Join can be explained with this query: // // SELECT * FROM base_table JOIN join_table - - Type int - Field *Field JoinTable *Table BasePKs []*Field JoinPKs []*Field @@ -34,10 +34,49 @@ type Relation struct { M2MJoinPKs []*Field } -// References returns true if the table to which the Relation belongs needs to declare a foreign key constraint to create the relation. -// For other relations, the constraint is created in either the referencing table (1:N, 'has-many' relations) or a mapping table (N:N, 'm2m' relations). +// References returns true if the table which defines this Relation +// needs to declare a foreign key constraint, as is the case +// for 'has-one' and 'belongs-to' relations. For other relations, +// the constraint is created either in the referencing table (1:N, 'has-many' relations) +// or the junction table (N:N, 'm2m' relations). +// +// Usage of `rel:` tag does not always imply creation of foreign keys (when WithForeignKeys() is not set) +// and can be used exclusively for joining tables at query time. For example: +// +// type User struct { +// ID int64 `bun:",pk"` +// Profile *Profile `bun:",rel:has-one,join:id=user_id"` +// } +// +// Creating a FK users.id -> profiles.user_id would be confusing and incorrect, +// so for such cases References() returns false. One notable exception to this rule +// is when a Relation is defined in a junction table, in which case it is perfectly +// fine for its primary keys to reference other tables. Consider: +// +// // UsersToGroups maps users to groups they follow. +// type UsersToGroups struct { +// UserID string `bun:"user_id,pk"` // Needs FK to users.id +// GroupID string `bun:"group_id,pk"` // Needs FK to groups.id +// +// User *User `bun:"rel:belongs-to,join:user_id=id"` +// Group *Group `bun:"rel:belongs-to,join:group_id=id"` +// } +// +// Here BooksToReaders has a composite primary key, composed of other primary keys. func (r *Relation) References() bool { - return r.Type == HasOneRelation || r.Type == BelongsToRelation + allPK := true + nonePK := true + for _, f := range r.BasePKs { + allPK = allPK && f.IsPK + nonePK = nonePK && !f.IsPK + } + + // Erring on the side of caution, only create foreign keys + // if the referencing columns are part of a composite PK + // in the junction table of the m2m relationship. + effectsM2M := r.Field.Table.IsM2MTable && allPK + + return (r.Type == HasOneRelation || r.Type == BelongsToRelation) && (effectsM2M || nonePK) } func (r *Relation) String() string { |