package psql import ( "fmt" "strings" "github.com/gobuffalo/flect" ) type DBSchema struct { ver int t map[string]*DBTableInfo rm map[string]map[string]*DBRel } type DBTableInfo struct { Name string Type string IsSingular bool Columns []DBColumn PrimaryCol *DBColumn TSVCol *DBColumn ColMap map[string]*DBColumn ColIDMap map[int16]*DBColumn Singular string Plural string } type RelType int const ( RelOneToOne RelType = iota + 1 RelOneToMany RelOneToManyThrough RelEmbedded RelRemote ) type DBRel struct { Type RelType Through string ColT string Left struct { col *DBColumn Table string Col string Array bool } Right struct { col *DBColumn Table string Col string Array bool } } func NewDBSchema(info *DBInfo, aliases map[string][]string) (*DBSchema, error) { schema := &DBSchema{ t: make(map[string]*DBTableInfo), rm: make(map[string]map[string]*DBRel), } for i, t := range info.Tables { err := schema.addTable(t, info.Columns[i], aliases) if err != nil { return nil, err } } for i, t := range info.Tables { err := schema.firstDegreeRels(t, info.Columns[i]) if err != nil { return nil, err } } for i, t := range info.Tables { err := schema.secondDegreeRels(t, info.Columns[i]) if err != nil { return nil, err } } return schema, nil } func (s *DBSchema) addTable( t DBTable, cols []DBColumn, aliases map[string][]string) error { colmap := make(map[string]*DBColumn, len(cols)) colidmap := make(map[int16]*DBColumn, len(cols)) singular := flect.Singularize(t.Key) plural := flect.Pluralize(t.Key) s.t[singular] = &DBTableInfo{ Name: t.Name, Type: t.Type, IsSingular: true, Columns: cols, ColMap: colmap, ColIDMap: colidmap, Singular: singular, Plural: plural, } s.t[plural] = &DBTableInfo{ Name: t.Name, Type: t.Type, IsSingular: false, Columns: cols, ColMap: colmap, ColIDMap: colidmap, Singular: singular, Plural: plural, } if al, ok := aliases[t.Key]; ok { for i := range al { k1 := flect.Singularize(al[i]) s.t[k1] = s.t[singular] k2 := flect.Pluralize(al[i]) s.t[k2] = s.t[plural] } } for i := range cols { c := &cols[i] switch { case c.Type == "tsvector": s.t[singular].TSVCol = c s.t[plural].TSVCol = c case c.PrimaryKey: s.t[singular].PrimaryCol = c s.t[plural].PrimaryCol = c } colmap[c.Key] = c colidmap[c.ID] = c } return nil } func (s *DBSchema) firstDegreeRels(t DBTable, cols []DBColumn) error { ct := t.Key cti, ok := s.t[ct] if !ok { return fmt.Errorf("invalid foreign key table '%s'", ct) } for i := range cols { c := cols[i] if len(c.FKeyTable) == 0 { continue } // Foreign key column name ft := strings.ToLower(c.FKeyTable) ti, ok := s.t[ft] if !ok { return fmt.Errorf("invalid foreign key table '%s'", ft) } // This is an embedded relationship like when a json/jsonb column // is exposed as a table if c.Name == c.FKeyTable && len(c.FKeyColID) == 0 { rel := &DBRel{Type: RelEmbedded} rel.Left.col = cti.PrimaryCol rel.Left.Table = cti.Name rel.Left.Col = cti.PrimaryCol.Name rel.Right.col = &c rel.Right.Table = ti.Name rel.Right.Col = c.Name if err := s.SetRel(ft, ct, rel); err != nil { return err } continue } if len(c.FKeyColID) == 0 { continue } // Foreign key column id fcid := c.FKeyColID[0] fc, ok := ti.ColIDMap[fcid] if !ok { return fmt.Errorf("invalid foreign key column id '%d' for table '%s'", fcid, ti.Name) } var rel1, rel2 *DBRel // One-to-many relation between current table and the // table in the foreign key if fc.UniqueKey { rel1 = &DBRel{Type: RelOneToOne} } else { rel1 = &DBRel{Type: RelOneToMany} } rel1.Left.col = &c rel1.Left.Table = t.Name rel1.Left.Col = c.Name rel1.Left.Array = c.Array rel1.Right.col = fc rel1.Right.Table = c.FKeyTable rel1.Right.Col = fc.Name rel1.Right.Array = fc.Array if err := s.SetRel(ct, ft, rel1); err != nil { return err } // One-to-many reverse relation between the foreign key table and the // the current table if c.UniqueKey { rel2 = &DBRel{Type: RelOneToOne} } else { rel2 = &DBRel{Type: RelOneToMany} } rel2.Left.col = fc rel2.Left.Table = c.FKeyTable rel2.Left.Col = fc.Name rel2.Left.Array = fc.Array rel2.Right.col = &c rel2.Right.Table = t.Name rel2.Right.Col = c.Name rel2.Right.Array = c.Array if err := s.SetRel(ft, ct, rel2); err != nil { return err } } return nil } func (s *DBSchema) secondDegreeRels(t DBTable, cols []DBColumn) error { jcols := make([]DBColumn, 0, len(cols)) ct := t.Key cti, ok := s.t[ct] if !ok { return fmt.Errorf("invalid foreign key table '%s'", ct) } for i := range cols { c := cols[i] if len(c.FKeyTable) == 0 { continue } // Foreign key column name ft := strings.ToLower(c.FKeyTable) ti, ok := s.t[ft] if !ok { return fmt.Errorf("invalid foreign key table '%s'", ft) } // This is an embedded relationship like when a json/jsonb column // is exposed as a table if c.Name == c.FKeyTable && len(c.FKeyColID) == 0 { continue } if len(c.FKeyColID) == 0 { continue } // Foreign key column id fcid := c.FKeyColID[0] if _, ok := ti.ColIDMap[fcid]; !ok { return fmt.Errorf("invalid foreign key column id '%d' for table '%s'", fcid, ti.Name) } jcols = append(jcols, c) } // If table contains multiple foreign key columns it's a possible // join table for many-to-many relationships or multiple one-to-many // relations // Below one-to-many relations use the current table as the // join table aka through table. if len(jcols) > 1 { for i := range jcols { for n := range jcols { if n == i { continue } err := s.updateSchemaOTMT(cti, jcols[i], jcols[n]) if err != nil { return err } } } } return nil } func (s *DBSchema) updateSchemaOTMT( ti *DBTableInfo, col1, col2 DBColumn) error { t1 := strings.ToLower(col1.FKeyTable) t2 := strings.ToLower(col2.FKeyTable) fc1, ok := s.t[t1].ColIDMap[col1.FKeyColID[0]] if !ok { return fmt.Errorf("invalid foreign key column id '%d' for table '%s'", col1.FKeyColID[0], ti.Name) } fc2, ok := s.t[t2].ColIDMap[col2.FKeyColID[0]] if !ok { return fmt.Errorf("invalid foreign key column id '%d' for table '%s'", col2.FKeyColID[0], ti.Name) } // One-to-many-through relation between 1nd foreign key table and the // 2nd foreign key table rel1 := &DBRel{Type: RelOneToManyThrough} rel1.Through = ti.Name rel1.ColT = col2.Name rel1.Left.col = &col2 rel1.Left.Table = col2.FKeyTable rel1.Left.Col = fc2.Name rel1.Right.col = &col1 rel1.Right.Table = ti.Name rel1.Right.Col = col1.Name if err := s.SetRel(t1, t2, rel1); err != nil { return err } // One-to-many-through relation between 2nd foreign key table and the // 1nd foreign key table rel2 := &DBRel{Type: RelOneToManyThrough} rel2.Through = ti.Name rel2.ColT = col1.Name rel1.Left.col = fc1 rel2.Left.Table = col1.FKeyTable rel2.Left.Col = fc1.Name rel1.Right.col = &col2 rel2.Right.Table = ti.Name rel2.Right.Col = col2.Name if err := s.SetRel(t2, t1, rel2); err != nil { return err } return nil } func (s *DBSchema) GetTableNames() []string { var names []string for name, _ := range s.t { names = append(names, name) } return names } func (s *DBSchema) GetTable(table string) (*DBTableInfo, error) { t, ok := s.t[table] if !ok { return nil, fmt.Errorf("unknown table '%s'", table) } return t, nil } func (s *DBSchema) SetRel(child, parent string, rel *DBRel) error { sp := strings.ToLower(flect.Singularize(parent)) pp := strings.ToLower(flect.Pluralize(parent)) sc := strings.ToLower(flect.Singularize(child)) pc := strings.ToLower(flect.Pluralize(child)) if _, ok := s.rm[sc]; !ok { s.rm[sc] = make(map[string]*DBRel) } if _, ok := s.rm[pc]; !ok { s.rm[pc] = make(map[string]*DBRel) } if _, ok := s.rm[sc][sp]; !ok { s.rm[sc][sp] = rel } if _, ok := s.rm[sc][pp]; !ok { s.rm[sc][pp] = rel } if _, ok := s.rm[pc][sp]; !ok { s.rm[pc][sp] = rel } if _, ok := s.rm[pc][pp]; !ok { s.rm[pc][pp] = rel } return nil } func (s *DBSchema) GetRel(child, parent string) (*DBRel, error) { rel, ok := s.rm[child][parent] if !ok { // No relationship found so this time fetch the table info // and try again in case child or parent was an alias ct, err := s.GetTable(child) if err != nil { return nil, err } pt, err := s.GetTable(parent) if err != nil { return nil, err } rel, ok = s.rm[ct.Name][pt.Name] if !ok { return nil, fmt.Errorf("unknown relationship '%s' -> '%s'", child, parent) } } return rel, nil }