fix as rename confusion

integrations/streamer_test.go

@@ -268,7 +268,7 @@ var viewCounts = stream
 
 errorCounts.join(viewCounts)
 		.as('errors', 'views')
-		.rename('error_view')
+		.streamName('error_view')
 		.eval(lambda: "errors.sum" / "views.sum")
 			.as('error_percent')
 		.httpOut('error_rate')

join.go

@@ -1,6 +1,9 @@
 package kapacitor
 
 import (
+	"fmt"
+	"strings"
+
 	"github.com/influxdb/kapacitor/models"
 	"github.com/influxdb/kapacitor/pipeline"
 )
@@ -12,6 +15,17 @@ type JoinNode struct {
 
 // Create a new  JoinNode, which takes pairs from parent streams combines them into a single point.
 func newJoinNode(et *ExecutingTask, n *pipeline.JoinNode) (*JoinNode, error) {
+	for _, name := range n.Names {
+		if len(name) == 0 {
+			return nil, fmt.Errorf("must provide a prefix name for the join node, see .as() property method")
+		}
+		if strings.ContainsRune(name, '.') {
+			return nil, fmt.Errorf("cannot use name %s as field prefix, it contains a '.' character", name)
+		}
+	}
+	if n.Names[0] == n.Names[1] {
+		return nil, fmt.Errorf("cannot use the same prefix name see .as() property method")
+	}
 	jn := &JoinNode{
 		j:    n,
 		node: node{Node: n, et: et},
@@ -22,7 +36,7 @@ func newJoinNode(et *ExecutingTask, n *pipeline.JoinNode) (*JoinNode, error) {
 
 func (j *JoinNode) runJoin() error {
 
-	rename := j.j.Rename
+	rename := j.j.StreamName
 	if rename == "" {
 		rename = j.parents[1].Name()
 	}

pipeline/join.go

@@ -8,10 +8,13 @@ package pipeline
 // Example:
 //    var errors = stream.fork().from('errors')
 //    var requests = stream.fork().from('requests')
-//    // Join the errors and requests stream
+//    // Join the errors and requests streams
 //    errors.join(requests)
+//            // Provide prefix names for the fields of the data points.
 //            .as('errors', 'requests')
-//            .rename('error_rate')
+//            .streamName('error_rate')
+//        // Both the "value" fields from each parent have been prefixed
+//        // with the respective names 'errors' and 'requests'.
 //        .eval(lambda: "errors.value" / "requests.value"))
 //           .as('rate')
 //        ...
@@ -28,7 +31,7 @@ type JoinNode struct {
 	Names []string
 	// The name of this new joined data stream.
 	// If empty the name of the left parent is used.
-	Rename string
+	StreamName string
 }
 
 func newJoinNode(e EdgeType, n Node) *JoinNode {
@@ -39,10 +42,14 @@ func newJoinNode(e EdgeType, n Node) *JoinNode {
 	return j
 }
 
-// The alias names to be used as a dot prefix for all field names for each
-// data point respectively.
+// Prefix names for all fields from the respective nodes.
+// Each field from the parent nodes will be prefixed with the provided name and a '.'.
+// See the example above.
+//
 // The name `nLeft` corresponds to the node on the left (i.e `leftNode.join(rightNode)`).
 // The name `nRight` corresponds to the node on the right.
+// The names cannot have a dot '.' character.
+//
 // tick:property
 func (j *JoinNode) As(nLeft, nRight string) *JoinNode {
 	//NOTE: the order is reversed because the second node is linked first