dialect/sql/sqlgraph: add function to order by edge terms (#3426)

2026-04-28 13:40:56 +03:00 · 2023-04-01 20:55:00 +03:00
parent 6f847a3492
commit 60bb939fc2
4 changed files with 399 additions and 41 deletions
--- a/dialect/sql/sqlgraph/graph.go
+++ b/dialect/sql/sqlgraph/graph.go
@@ -82,8 +82,6 @@ type Step struct {
 		Columns []string
 		// Inverse indicates if the edge is an inverse edge.
 		Inverse bool
-		// Name allows giving this edge a name for making queries more readable.
-		Name string
 	}
 	// To is the dest of the path (the neighbors).
 	To struct {
@@ -292,12 +290,14 @@ func HasNeighborsWith(q *sql.Selector, s *Step, pred func(*sql.Selector)) {
 type (
 	// OrderByOptions holds the information needed to order a query by an edge.
 	OrderByOptions struct {
-		// Step to get the edge to order by.
+		// Step to get the edge to order by its count.
 		Step *Step
-		// Desc indicates if the ordering should be descending.
-		// When false, nulls are ordered first. When true, nulls
-		// are ordered last.
+		// Desc indicates if the ordering should be in descending order. When false, NULL values
+		// are ordered first (default in MySQL and SQLite). When true, NULLs are ordered last.
 		Desc bool
+		// Terms used for non-aggregation ordering.
+		// See, OrderByNeighborTerms for more info.
+		Terms []OrderByTerm
 	}
 	// OrderByInfo holds the information done by the OrderBy functions.
 	OrderByInfo struct {
@@ -307,21 +307,90 @@ type (
 	OrderByTerm struct {
 		Column string      // Column name. If empty, an expression is used.
 		Expr   sql.Querier // Expression. If nil, the column is used.
+		As     string      // Optional alias.
 		Type   field.Type  // Term type.
+		Desc   bool        // Descending order.
 	}
+	// OrderByOption allows configuring OrderByOptions using functional options.
+	OrderByOption func(*OrderByOptions)
 )

+// OrderDesc sets the order to be descending order.
+// This option is valid only for a single count order.
+func OrderDesc() OrderByOption {
+	return func(opts *OrderByOptions) {
+		opts.Desc = true
+	}
+}
+
+// OrderByExpr appends an expression to the order by clause.
+func OrderByExpr(x sql.Querier, as string) OrderByOption {
+	return func(opts *OrderByOptions) {
+		opts.Terms = append(opts.Terms, OrderByTerm{
+			Expr: x,
+			As:   as,
+		})
+	}
+}
+
+// OrderByExprDesc appends an expression to the order by clause in descending order.
+func OrderByExprDesc(x sql.Querier, as string) OrderByOption {
+	return func(opts *OrderByOptions) {
+		opts.Terms = append(opts.Terms, OrderByTerm{
+			Expr: x,
+			As:   as,
+			Desc: true,
+		})
+	}
+}
+
+// OrderByColumn appends a column to the order by clause.
+func OrderByColumn(c string) OrderByOption {
+	return func(opts *OrderByOptions) {
+		opts.Terms = append(opts.Terms, OrderByTerm{
+			Column: c,
+		})
+	}
+}
+
+// OrderByColumnDesc appends a column to the order by clause in descending order.
+func OrderByColumnDesc(c string) OrderByOption {
+	return func(opts *OrderByOptions) {
+		opts.Terms = append(opts.Terms, OrderByTerm{
+			Column: c,
+			Desc:   true,
+		})
+	}
+}
+
+// NewOrderBy gets list of options and returns a configured order-by.
+//
+//	NewOrderBy(
+//		sqlgraph.NewStep(
+//			sqlgraph.From(user.Table, user.FieldID),
+//			sqlgraph.To(group.Table, group.FieldID),
+//			sqlgraph.Edge(sqlgraph.M2M, false, user.GroupsTable, user.GroupsPrimaryKey...),
+//		),
+//		OrderByExpr(
+//			sql.Expr("SUM(age)"),
+//			"sum_age",
+//		),
+//	)
+func NewOrderBy(s *Step, opts ...OrderByOption) *OrderByOptions {
+	r := &OrderByOptions{Step: s}
+	for _, opt := range opts {
+		opt(r)
+	}
+	return r
+}
+
 // countAlias returns the alias to use for the count column.
 func countAlias(q *sql.Selector, s *Step) string {
-	eName := s.Edge.Name
-	if eName == "" {
-		eName = s.To.Table
-	}
 	selected := make(map[string]struct{})
 	for _, c := range q.SelectedColumns() {
 		selected[c] = struct{}{}
 	}
-	column := fmt.Sprintf("count_%s", eName)
+	column := fmt.Sprintf("count_%s", s.To.Table)
 	// If the column was already selected,
 	// try to find a free alias.
 	if _, ok := selected[column]; ok {
@@ -335,12 +404,12 @@ func countAlias(q *sql.Selector, s *Step) string {
 	return column
 }

-// OrderByCountNeighbors appends ordering based on the number of neighbors.
+// OrderByNeighborsCount appends ordering based on the number of neighbors.
 // For example, order users by their number of posts.
-// HasNeighbors applies on the given Selector a neighbors check.
-func OrderByCountNeighbors(q *sql.Selector, opts *OrderByOptions) *OrderByInfo {
+func OrderByNeighborsCount(q *sql.Selector, opts *OrderByOptions) *OrderByInfo {
 	var (
 		countC string
+		join   *sql.Selector
 		build  = sql.Dialect(q.Dialect())
 	)
 	switch s, r := opts.Step, opts.Step.Edge.Rel; {
@@ -368,47 +437,120 @@ func OrderByCountNeighbors(q *sql.Selector, opts *OrderByOptions) *OrderByInfo {
 			pk1 = s.Edge.Columns[1]
 		}
 		joinT := build.Table(s.Edge.Table).Schema(s.Edge.Schema)
-		to := build.Select(
+		join = build.Select(
 			joinT.C(pk1),
 			build.String(func(b *sql.Builder) {
 				b.WriteString("COUNT(*) AS ").Ident(countC)
 			}),
 		).From(joinT).GroupBy(joinT.C(pk1))
-		q.LeftJoin(to).
+		q.LeftJoin(join).
 			On(
 				q.C(s.From.Column),
-				to.C(pk1),
+				join.C(pk1),
 			)
 	case r == O2M || (r == O2O && !s.Edge.Inverse):
 		countC = countAlias(q, s)
 		edgeT := build.Table(s.Edge.Table).Schema(s.Edge.Schema)
-		to := build.Select(
+		join = build.Select(
 			edgeT.C(s.Edge.Columns[0]),
 			build.String(func(b *sql.Builder) {
 				b.WriteString("COUNT(*) AS ").Ident(countC)
 			}),
 		).From(edgeT).GroupBy(edgeT.C(s.Edge.Columns[0]))
-		q.LeftJoin(to).
+		q.LeftJoin(join).
 			On(
 				q.C(s.From.Column),
-				to.C(s.Edge.Columns[0]),
+				join.C(s.Edge.Columns[0]),
 			)
 	}
-	q.OrderExpr(
-		build.Expr(func(b *sql.Builder) {
-			b.WriteString("COALESCE(").Ident(countC).WriteString(", 0)")
-			if opts.Desc {
+	terms := []OrderByTerm{
+		{Column: countC, Type: field.TypeInt, Desc: opts.Desc},
+	}
+	orderTerms(q, join, terms)
+	return &OrderByInfo{Terms: terms}
+}
+
+func orderTerms(q, join *sql.Selector, ts []OrderByTerm) {
+	for _, t := range ts {
+		t := t
+		q.OrderExprFunc(func(b *sql.Builder) {
+			switch {
+			case t.As != "":
+				b.WriteString(join.C(t.As))
+			case t.Column != "":
+				b.WriteString(join.C(t.Column))
+			case t.Expr != nil:
+				b.Join(t.Expr)
+			}
+			// Unlike MySQL and SQLite, NULL values sort as if larger than any other value.
+			// Therefore, we need to explicitly order NULLs first on ASC and last on DESC.
+			switch pg := b.Dialect() == dialect.Postgres; {
+			case pg && t.Desc:
+				b.WriteString(" DESC NULLS LAST")
+			case pg:
+				b.WriteString(" NULLS FIRST")
+			case t.Desc:
 				b.WriteString(" DESC")
 			}
-		}),
-	)
-	return &OrderByInfo{
-		Terms: []OrderByTerm{
-			{Column: countC, Type: field.TypeInt},
-		},
+		})
 	}
 }

+func selectTerms(q *sql.Selector, ts []OrderByTerm) {
+	for _, t := range ts {
+		switch {
+		case t.Column != "" && t.As != "":
+			q.AppendSelect(q.C(t.Column), t.As)
+		case t.Column != "":
+			q.AppendSelect(q.C(t.Column))
+		case t.Expr != nil:
+			q.AppendSelectExprAs(t.Expr, t.As)
+		}
+	}
+}
+
+// OrderByNeighborTerms appends ordering based on the number of neighbors.
+// For example, order users by their number of posts.
+func OrderByNeighborTerms(q *sql.Selector, opts *OrderByOptions) {
+	var (
+		join  *sql.Selector
+		build = sql.Dialect(q.Dialect())
+	)
+	switch s, r := opts.Step, opts.Step.Edge.Rel; {
+	case r == M2O || (r == O2O && s.Edge.Inverse):
+		toT := build.Table(s.To.Table).Schema(s.To.Schema)
+		join = build.Select(toT.C(s.To.Column)).
+			From(toT)
+		selectTerms(join, opts.Terms)
+		q.LeftJoin(join).
+			On(q.C(s.Edge.Columns[0]), join.C(s.To.Column))
+	case r == M2M:
+		pk1, pk2 := s.Edge.Columns[1], s.Edge.Columns[0]
+		if s.Edge.Inverse {
+			pk1, pk2 = pk2, pk1
+		}
+		toT := build.Table(s.To.Table).Schema(s.To.Schema)
+		joinT := build.Table(s.Edge.Table).Schema(s.Edge.Schema)
+		join = build.Select(pk2).
+			From(toT).
+			Join(joinT).
+			On(toT.C(s.To.Column), joinT.C(pk1)).
+			GroupBy(pk2)
+		selectTerms(join, opts.Terms)
+		q.LeftJoin(join).
+			On(q.C(s.From.Column), join.C(pk2))
+	case r == O2M || (r == O2O && !s.Edge.Inverse):
+		toT := build.Table(s.Edge.Table).Schema(s.Edge.Schema)
+		join = build.Select(toT.C(s.Edge.Columns[0])).
+			From(toT).
+			GroupBy(toT.C(s.Edge.Columns[0]))
+		selectTerms(join, opts.Terms)
+		q.LeftJoin(join).
+			On(q.C(s.From.Column), join.C(s.Edge.Columns[0]))
+	}
+	orderTerms(q, join, opts.Terms)
+}
+
 type (
 	// FieldSpec holds the information for updating a field
 	// column in the database.