From daf62d60148c4a4b464e01286ddeb945c92c18f6 Mon Sep 17 00:00:00 2001
From: Manish R Jain <manish@dgraph.io>
Date: Fri, 20 May 2016 20:19:05 +1000
Subject: [PATCH] Add comments to clarify how ToJson works.
---
query/query.go | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/query/query.go b/query/query.go
index b14d1548..58d0db76 100644
--- a/query/query.go
+++ b/query/query.go
@@ -180,6 +180,17 @@ func postTraverse(g *SubGraph) (result map[uint64]interface{}, rerr error) {
r.ValuesLength(), q.UidsLength())
}
+ // Generate a matrix of maps
+ // Row -> .....
+ // Col
+ // |
+ // v
+ // map{_uid_ = uid}
+ // If some result is present from children results, then merge.
+ // Otherwise, this would only contain the _uid_ property.
+ // result[uid in row] = map[cur attribute ->
+ // list of maps of {uid, uid + children result}]
+ //
var ul task.UidList
for i := 0; i < r.UidmatrixLength(); i++ {
if ok := r.Uidmatrix(&ul, i); !ok {
@@ -201,6 +212,7 @@ func postTraverse(g *SubGraph) (result map[uint64]interface{}, rerr error) {
m[g.Attr] = l
result[q.Uids(i)] = m
}
+ // TODO(manish): Check what happens if we handle len(l) == 1 separately.
}
var tv task.Value
@@ -210,6 +222,9 @@ func postTraverse(g *SubGraph) (result map[uint64]interface{}, rerr error) {
}
val := tv.ValBytes()
if bytes.Equal(val, nil) {
+ // We do this, because we typically do set values, even though
+ // they might be nil. This is to ensure that the index of the query uids
+ // and the index of the results can remain in sync.
continue
}
@@ -217,7 +232,7 @@ func postTraverse(g *SubGraph) (result map[uint64]interface{}, rerr error) {
glog.WithField("prev", pval).
WithField("_uid_", q.Uids(i)).
WithField("new", val).
- Fatal("Previous value detected.")
+ Fatal("Previous value detected. A uid -> list of uids / value. Not both.")
}
m := make(map[string]interface{})
m["_uid_"] = fmt.Sprintf("%#x", q.Uids(i))
--
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