go-driver
go-driver copied to clipboard
arangodb
Query on a view - the cursor returns an empty document
Is it supported to do AQL queries on views with the driver? I have a simple collection with a view defined on it with includeAllFields set to true, no other options set.
Environment:
- github.com/arangodb/go-driver v0.0.0-20200811070917-cc2b983cf602
- go version go1.13.4 linux/amd64
- ArangoDB v3.7.1
If I do the following in the query editor: RETURN (FOR v IN vvariants SEARCH v.chr == 5 RETURN v._key)
The result is
[
[
"14681832"
]
]
If in code:
var variants interface{} // or []string, either returns empty document
query := `RETURN (FOR v IN vvariants SEARCH v.chr == @chr RETURN v._key)`
bindVars := map[string]interface{}{"chr": 5}
cursor, err := db.Query(ctx, query, bindVars)
if err != nil {
fmt.Println("Query failed:", err)
return variants, err
}
defer cursor.Close()
if cursor.HasMore() {
_, err = cursor.ReadDocument(ctx, &variants)
if err != nil {
fmt.Println("Failed to read document:", err)
return variants, err
}
fmt.Println(variants) // prints []
} else {
fmt.Println("No documents found")
}
return variants, nil
I expect to see the same result as the query editor, but the document read from the cursor is empty? I can't see what I am doing wrong, is it supposed to be supported? Thanks!
Can anyone confirm? I believe this is a bug in the driver, where documents can't be returned from Database.Query if the AQL query is returning a document or projection from a view.
The same AQL query will work in the arangoDB query editor, and I also don't think it is a problem with the view updating itself as I have added time.Sleep before executing the query to no effect, so it is definitely driver specific.
I have found a workaround, which is to use AQL to query the view and return the results in a variable, which can then be used to filter and return documents on the actual collections rather than the view, which still allows me to use views.
Out of curiosity I gave this a shot. I swear I was able to reproduce it, even though the response over the wire was identical to an identical FILTER query. But I can no longer reproduce it, even after bouncing the server...
My best guess is that A) it's some kind of time delay after creating a View, where the Coordinator (or similar) hasn't caught up, or B) some kind of state was knocked loose when I tried setting AllowDirtyReads on the query, ala:
...
t := true
newCtx := godriver.WithAllowDirtyReads(ctx, &t)
cursor, err := db.Query(newCtx, query, bindVars)
...
But as of now your example works for me (on [email protected] and go-driver@master, FWIW).
