Expose more information about join tables

bdb/relationships.go

@@ -7,7 +7,11 @@ type ToManyRelationship struct {
 	Column        string
 	ForeignTable  string
 	ForeignColumn string
-	ToJoinTable   bool
+
+	ToJoinTable       bool
+	JoinTable         string
+	JoinLocalColumn   string
+	JoinForeignColumn string
 }
 
 // ToManyRelationships relationship lookups
@@ -25,16 +29,38 @@ func ToManyRelationships(table string, tables []Table) []ToManyRelationship {
 				continue
 			}
 
-			relationship := ToManyRelationship{
+			relationships = append(relationships, buildRelationship(table, f, t))
-				Column:        f.ForeignColumn,
-				ForeignTable:  t.Name,
-				ForeignColumn: f.Column,
-				ToJoinTable:   t.IsJoinTable,
-			}
-
-			relationships = append(relationships, relationship)
 		}
 	}
 
 	return relationships
 }
+
+func buildRelationship(localTable string, foreignKey ForeignKey, foreignTable Table) ToManyRelationship {
+	if !foreignTable.IsJoinTable {
+		return ToManyRelationship{
+			Column:        foreignKey.ForeignColumn,
+			ForeignTable:  foreignTable.Name,
+			ForeignColumn: foreignKey.Column,
+			ToJoinTable:   foreignTable.IsJoinTable,
+		}
+	}
+
+	relationship := ToManyRelationship{
+		Column:      foreignKey.ForeignColumn,
+		ToJoinTable: true,
+		JoinTable:   foreignTable.Name,
+	}
+
+	for _, fk := range foreignTable.FKeys {
+		if fk.ForeignTable != localTable {
+			relationship.JoinForeignColumn = fk.Column
+			relationship.ForeignTable = fk.ForeignTable
+			relationship.ForeignColumn = fk.ForeignColumn
+		} else {
+			relationship.JoinLocalColumn = fk.Column
+		}
+	}
+
+	return relationship
+}

bdb/relationships_test.go

@@ -1,14 +1,17 @@
 package bdb
 
-import "testing"
+import (
+	"testing"
+
+	"github.com/davecgh/go-spew/spew"
+)
 
 func TestToManyRelationships(t *testing.T) {
 	t.Parallel()
 
 	tables := []Table{
 		Table{
-			Name:        "videos",
+			Name: "videos",
-			IsJoinTable: true,
 			FKeys: []ForeignKey{
 				{Name: "videos_user_id_fk", Column: "user_id", ForeignTable: "users", ForeignColumn: "id"},
 				{Name: "videos_contest_id_fk", Column: "contest_id", ForeignTable: "contests", ForeignColumn: "id"},
@@ -21,9 +24,22 @@ func TestToManyRelationships(t *testing.T) {
 				{Name: "notifications_source_id_fk", Column: "source_id", ForeignTable: "users", ForeignColumn: "id"},
 			},
 		},
+		Table{
+			Name:        "users_video_tags",
+			IsJoinTable: true,
+			FKeys: []ForeignKey{
+				{Name: "user_id_fk", Column: "user_id", ForeignTable: "users", ForeignColumn: "id"},
+				{Name: "video_id_fk", Column: "video_id", ForeignTable: "videos", ForeignColumn: "id"},
+			},
+		},
 	}
 
 	relationships := ToManyRelationships("users", tables)
+	spew.Dump(relationships)
+	if len(relationships) != 4 {
+		t.Error("wrong # of relationships:", len(relationships))
+	}
+
 	r := relationships[0]
 	if r.Column != "id" {
 		t.Error("wrong local column:", r.Column)
@@ -34,7 +50,58 @@ func TestToManyRelationships(t *testing.T) {
 	if r.ForeignColumn != "user_id" {
 		t.Error("wrong foreign column:", r.ForeignColumn)
 	}
+	if r.ToJoinTable {
+		t.Error("not a join table")
+	}
+
+	r = relationships[1]
+	if r.Column != "id" {
+		t.Error("wrong local column:", r.Column)
+	}
+	if r.ForeignTable != "notifications" {
+		t.Error("wrong foreign table:", r.ForeignTable)
+	}
+	if r.ForeignColumn != "user_id" {
+		t.Error("wrong foreign column:", r.ForeignColumn)
+	}
+	if r.ToJoinTable {
+		t.Error("not a join table")
+	}
+
+	r = relationships[2]
+	if r.Column != "id" {
+		t.Error("wrong local column:", r.Column)
+	}
+	if r.ForeignTable != "notifications" {
+		t.Error("wrong foreign table:", r.ForeignTable)
+	}
+	if r.ForeignColumn != "source_id" {
+		t.Error("wrong foreign column:", r.ForeignColumn)
+	}
+	if r.ToJoinTable {
+		t.Error("not a join table")
+	}
+
+	r = relationships[3]
+	if r.Column != "id" {
+		t.Error("wrong local column:", r.Column)
+	}
+	if r.ForeignColumn != "id" {
+		t.Error("wrong foreign column:", r.Column)
+	}
+	if r.ForeignTable != "videos" {
+		t.Error("wrong foreign table:", r.ForeignTable)
+	}
+	if r.JoinTable != "users_video_tags" {
+		t.Error("wrong join table:", r.ForeignTable)
+	}
+	if r.JoinLocalColumn != "user_id" {
+		t.Error("wrong local join column:", r.JoinLocalColumn)
+	}
+	if r.JoinForeignColumn != "video_id" {
+		t.Error("wrong foreign join column:", r.JoinForeignColumn)
+	}
 	if !r.ToJoinTable {
-		t.Error("expected a join table - kind of - not really but we're faking it")
+		t.Error("expected a join table")
 	}
 }