Add various flavors of Join to the chain

db/chain/chain.go

@@ -379,6 +379,62 @@ func (ec *ExpresionChain) Join(expr string, args ...interface{}) *ExpresionChain
 	return ec
 }
 
+// LeftJoin adds a 'LEFT JOIN' to the 'ExpresionChain' and returns the same chan to facilitate
+// further chaining.
+// THIS DOES NOT CREATE A COPY OF THE CHAIN, IT MUTATES IN PLACE.
+func (ec *ExpresionChain) LeftJoin(expr string, args ...interface{}) *ExpresionChain {
+	ec.append(
+		querySegmentAtom{
+			segment:   sqlLeftJoin,
+			expresion: expr,
+			arguments: args,
+			sqlBool:   SQLNothing,
+		})
+	return ec
+}
+
+// RightJoin adds a 'RIGHT JOIN' to the 'ExpresionChain' and returns the same chan to facilitate
+// further chaining.
+// THIS DOES NOT CREATE A COPY OF THE CHAIN, IT MUTATES IN PLACE.
+func (ec *ExpresionChain) RightJoin(expr string, args ...interface{}) *ExpresionChain {
+	ec.append(
+		querySegmentAtom{
+			segment:   sqlRightJoin,
+			expresion: expr,
+			arguments: args,
+			sqlBool:   SQLNothing,
+		})
+	return ec
+}
+
+// InnerJoin adds a 'INNER JOIN' to the 'ExpresionChain' and returns the same chan to facilitate
+// further chaining.
+// THIS DOES NOT CREATE A COPY OF THE CHAIN, IT MUTATES IN PLACE.
+func (ec *ExpresionChain) InnerJoin(expr string, args ...interface{}) *ExpresionChain {
+	ec.append(
+		querySegmentAtom{
+			segment:   sqlInnerJoin,
+			expresion: expr,
+			arguments: args,
+			sqlBool:   SQLNothing,
+		})
+	return ec
+}
+
+// OuterJoin adds a 'OUTER JOIN' to the 'ExpresionChain' and returns the same chan to facilitate
+// further chaining.
+// THIS DOES NOT CREATE A COPY OF THE CHAIN, IT MUTATES IN PLACE.
+func (ec *ExpresionChain) OuterJoin(expr string, args ...interface{}) *ExpresionChain {
+	ec.append(
+		querySegmentAtom{
+			segment:   sqlOuterJoin,
+			expresion: expr,
+			arguments: args,
+			sqlBool:   SQLNothing,
+		})
+	return ec
+}
+
 // OrderBy adds a 'ORDER BY' to the 'ExpresionChain' and returns the same chan to facilitate
 // further chaining.
 // THIS DOES NOT CREATE A COPY OF THE CHAIN, IT MUTATES IN PLACE.
@@ -640,16 +696,18 @@ func (ec *ExpresionChain) render(raw bool) (string, []interface{}, error) {
 		ec.mainOperation.segment == sqlUpdate {
 		// JOIN
 		joins := extract(ec, sqlJoin)
+		joins = append(joins, extract(ec, sqlLeftJoin)...)
+		joins = append(joins, extract(ec, sqlRightJoin)...)
+		joins = append(joins, extract(ec, sqlInnerJoin)...)
+		joins = append(joins, extract(ec, sqlOuterJoin)...)
 		if len(joins) != 0 {
-			joinSubQueries := make([]string, len(joins))
-			joinArguments := []interface{}{}
-			for i, item := range joins {
-				joinSubQueries[i] = item.expresion
-				joinArguments = append(joinArguments, item.arguments...)
+			for _, join := range joins {
+
+				query += fmt.Sprintf(" %s %s",
+					join.segment,
+					join.expresion)
+				args = append(args, join.arguments...)
 			}
-			query += fmt.Sprintf(" JOIN %s",
-				strings.Join(joinSubQueries, " "))
-			args = append(args, joinArguments...)
 		}
 	}
 

db/chain/chain_test.go

@@ -155,6 +155,23 @@ func TestExpresionChain_Render(t *testing.T) {
 			wantArgs: []interface{}{"unpirulo", 1, 2, "pajarito"},
 			wantErr:  false,
 		},
+		{
+			name: "basic selection with flavors of JOIN",
+			chain: (&ExpresionChain{}).Select("field1", "field2", "field3").
+				Table("convenient_table").
+				AndWhere("field1 > ?", 1).
+				AndWhere("field2 = ?", 2).
+				AndWhere("field3 > ?", "pajarito").
+				Join(JoinOn("another_convenient_table", "pirulo = ?", "unpirulo")).
+				Join(JoinOn("yet_another_convenient_table", "pirulo = ?", "otrounpirulo")).
+				LeftJoin(JoinOn("one_convenient_table", "pirulo2 = ?", "dospirulo")).
+				RightJoin(JoinOn("three_convenient_table", "pirulo3 = ?", "trespirulo")).
+				InnerJoin(JoinOn("four_convenient_table", "pirulo4 = ?", "cuatropirulo")).
+				OuterJoin(JoinOn("five_convenient_table", "pirulo5 = ?", "cincopirulo")),
+			want:     "SELECT field1, field2, field3 FROM convenient_table JOIN another_convenient_table ON pirulo = $1 JOIN yet_another_convenient_table ON pirulo = $2 LEFT JOIN one_convenient_table ON pirulo2 = $3 RIGHT JOIN three_convenient_table ON pirulo3 = $4 INNER JOIN four_convenient_table ON pirulo4 = $5 OUTER JOIN five_convenient_table ON pirulo5 = $6 WHERE field1 > $7 AND field2 = $8 AND field3 > $9",
+			wantArgs: []interface{}{"unpirulo", "otrounpirulo", "dospirulo", "trespirulo", "cuatropirulo", "cincopirulo", 1, 2, "pajarito"},
+			wantErr:  false,
+		},
 		{
 			name: "basic selection with where and join and group by",
 			chain: (&ExpresionChain{}).Select("field1", "field2", "field3").

db/chain/helpers.go

@@ -103,3 +103,10 @@ func Null(field string) string {
 func SetToCurrentTimestamp(field string) string {
 	return fmt.Sprintf("%s = %s", field, CurrentTimestampPGFn)
 }
+
+// JOIN helpers
+
+// JoinOn crafts the `table ON expression`
+func JoinOn(table, expr string, args ...interface{}) (string, []interface{}) {
+	return fmt.Sprintf("%s ON %s", table, expr), args
+}

db/chain/segment.go

@@ -39,17 +39,21 @@ const (
 type sqlSegment string
 
 const (
-	sqlWhere  sqlSegment = "WHERE"
-	sqlLimit  sqlSegment = "LIMIT"
-	sqlOffset sqlSegment = "OFFSET"
-	sqlJoin   sqlSegment = "JOIN"
-	sqlSelect sqlSegment = "SELECT"
-	sqlDelete sqlSegment = "DELETE"
-	sqlInsert sqlSegment = "INSERT"
-	sqlUpdate sqlSegment = "UPDATE"
-	sqlFrom   sqlSegment = "FROM"
-	sqlGroup  sqlSegment = "GROUP BY"
-	sqlOrder  sqlSegment = "ORDER BY"
+	sqlWhere     sqlSegment = "WHERE"
+	sqlLimit     sqlSegment = "LIMIT"
+	sqlOffset    sqlSegment = "OFFSET"
+	sqlJoin      sqlSegment = "JOIN"
+	sqlLeftJoin  sqlSegment = "LEFT JOIN"
+	sqlRightJoin sqlSegment = "RIGHT JOIN"
+	sqlInnerJoin sqlSegment = "INNER JOIN"
+	sqlOuterJoin sqlSegment = "OUTER JOIN"
+	sqlSelect    sqlSegment = "SELECT"
+	sqlDelete    sqlSegment = "DELETE"
+	sqlInsert    sqlSegment = "INSERT"
+	sqlUpdate    sqlSegment = "UPDATE"
+	sqlFrom      sqlSegment = "FROM"
+	sqlGroup     sqlSegment = "GROUP BY"
+	sqlOrder     sqlSegment = "ORDER BY"
 	// SPECIAL CASES
 	sqlInsertMulti sqlSegment = "INSERTM"
 )