fix expand(_all_) in recurse queries

query/common_test.go

@@ -317,6 +317,17 @@ office.room                    : uid .
 	addPassword(t, 1, "password", "123456")
 	addPassword(t, 23, "pass", "654321")
 
+	addEdgeToUID(t, "school", 32, 33, nil)
+	addEdgeToUID(t, "district", 33, 34, nil)
+	addEdgeToUID(t, "county", 34, 35, nil)
+	addEdgeToUID(t, "state", 35, 36, nil)
+
+	addEdgeToValue(t, "name", 33, "San Mateo High School", nil)
+	addEdgeToValue(t, "name", 34, "San Mateo School District", nil)
+	addEdgeToValue(t, "name", 35, "San Mateo County", nil)
+	addEdgeToValue(t, "name", 36, "California", nil)
+	addEdgeToValue(t, "abbr", 36, "CA", nil)
+
 	// So, user we're interested in has uid: 1.
 	// She has 5 friends: 23, 24, 25, 31, and 101
 	addEdgeToUID(t, "friend", 1, 23, nil)

query/query3_test.go

@@ -51,6 +51,34 @@ func TestRecurseQuery(t *testing.T) {
 		`{"data": {"me":[{"name":"Michonne", "friend":[{"name":"Rick Grimes", "friend":[{"name":"Michonne"}]},{"name":"Glenn Rhee"},{"name":"Daryl Dixon"},{"name":"Andrea", "friend":[{"name":"Glenn Rhee"}]}]}]}}`, js)
 }
 
+func TestRecurseExpand(t *testing.T) {
+
+	query := `
+		{
+			me(func: uid(32)) @recurse {
+				expand(_all_)
+			}
+		}`
+	js := processToFastJsonNoErr(t, query)
+	require.JSONEq(t, `{"data":{"me":[{"school":[{"name":"San Mateo High School","district":[{"name":"San Mateo School District","county":[{"state":[{"name":"California","abbr":"CA"}],"name":"San Mateo County"}]}]}]}]}}`, js)
+}
+
+func TestRecurseExpandRepeatedPredError(t *testing.T) {
+
+	query := `
+		{
+			me(func: uid(32)) @recurse {
+				name
+				expand(_all_)
+			}
+		}`
+
+	ctx := defaultContext()
+	_, err := processToFastJsonCtxVars(t, query, ctx, nil)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "Repeated subgraph: [name] while using expand()")
+}
+
 func TestRecurseQueryOrder(t *testing.T) {
 
 	query := `

query/recurse.go

@@ -9,6 +9,7 @@ package query
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"math"
 
@@ -49,22 +50,11 @@ func (start *SubGraph) expandRecurse(ctx context.Context, maxDepth uint64) error
 		return ctx.Err()
 	}
 
-	// Add children back so that expandSubgraph can expand them if needed.
-	start.Children = append(start.Children, startChildren...)
-	if startChildren, err = expandSubgraph(ctx, start); err != nil {
+	// Add children back and expand if necessary
+	if exec, err = expandChildren(ctx, start, startChildren); err != nil {
 		return err
 	}
 
-	start.Children = start.Children[:0]
-	for _, child := range startChildren {
-		temp := new(SubGraph)
-		temp.copyFiltersRecurse(child)
-		temp.SrcUIDs = start.DestUIDs
-		temp.Params.Var = child.Params.Var
-		exec = append(exec, temp)
-		start.Children = append(start.Children, temp)
-	}
-
 	dummy := &SubGraph{}
 	var depth uint64
 	for {
@@ -140,18 +130,15 @@ func (start *SubGraph) expandRecurse(ctx context.Context, maxDepth uint64) error
 
 		// modify the exec and attach child nodes.
 		var out []*SubGraph
+		var exp []*SubGraph
 		for _, sg := range exec {
 			if len(sg.DestUIDs.Uids) == 0 {
 				continue
 			}
-			for _, child := range startChildren {
-				temp := new(SubGraph)
-				temp.copyFiltersRecurse(child)
-				temp.SrcUIDs = sg.DestUIDs
-				temp.Params.Var = child.Params.Var
-				sg.Children = append(sg.Children, temp)
-				out = append(out, temp)
+			if exp, err = expandChildren(ctx, sg, startChildren); err != nil {
+				return err
 			}
+			out = append(out, exp...)
 		}
 
 		if numEdges > x.Config.QueryEdgeLimit {
@@ -166,6 +153,31 @@ func (start *SubGraph) expandRecurse(ctx context.Context, maxDepth uint64) error
 	}
 }
 
+// expandChildren adds child nodes to a SubGraph with no children, expanding them if necessary.
+func expandChildren(ctx context.Context, sg *SubGraph, children []*SubGraph) ([]*SubGraph, error) {
+	if len(sg.Children) > 0 {
+		return nil, errors.New("Subgraph should not have any children")
+	}
+	// Add children and expand if necessary
+	sg.Children = append(sg.Children, children...)
+	expandedChildren, err := expandSubgraph(ctx, sg)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]*SubGraph, 0, len(expandedChildren))
+	sg.Children = sg.Children[:0]
+	// Link new child nodes back to parent destination UIDs
+	for _, child := range expandedChildren {
+		newChild := new(SubGraph)
+		newChild.copyFiltersRecurse(child)
+		newChild.SrcUIDs = sg.DestUIDs
+		newChild.Params.Var = child.Params.Var
+		sg.Children = append(sg.Children, newChild)
+		out = append(out, newChild)
+	}
+	return out, nil
+}
+
 func Recurse(ctx context.Context, sg *SubGraph) error {
 	if !sg.Params.Recurse {
 		return x.Errorf("Invalid recurse path query")