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Handle nils in filesystem #50
Conversation
dimitern
reviewed
Apr 28, 2016
| coerced, err := checker.Coerce(source, nil) | ||
| if err != nil { | ||
| return nil, WrapWithDeserializationError(err, "filesystem 2.0 schema check failed") | ||
| } | ||
| valid := coerced.(map[string]interface{}) | ||
| // From here we know that the map returned from the schema coercion | ||
| // contains fields of the right type. | ||
| - | ||
| + mount_point, ok := valid["mount_point"].(string) |
dimitern
Apr 28, 2016
Contributor
no need for the if !ok check, as when not present mount_point will be "".
mount_point, _ := valid["mount_point"].(string)
dimitern
Apr 28, 2016
Contributor
It works, but it can be misleading at first glance:
value, ok := someMapStringString["missing-key"] -> value = "", ok = false
value, _ := someMapStringString["missing-key"] -> value = "", no panic
value := someMapStringString["missing-key"] -> value = "", no panic
On the other hand:
value, ok := someNonStringInterfaceValue.(string) -> value = "", ok = false
value, _ := someNonStringInterfaceValue.(string) -> value = "", no panic
value := someNonStringInterfaceValue.(string) -> panics
We have both cases in one, so:
value, _ := mapStringInterface["missing-key"].(string) -> value = "" (i.e. we got a non-nil interface{} value with a wrapped nil in it due to the map lookup, but then trying to type assert that value to a string still returns "" and will panic without _ on the second return)
frobware
commented
Apr 28, 2016
|
LGTM |
dimitern
reviewed
Apr 28, 2016
| + if !ok { | ||
| + mount_point = "" | ||
| + } | ||
| + label, ok := valid["label"].(string) |
|
LGTM with a couple of suggestions for simplification. |
babbageclunk
reviewed
Apr 28, 2016
| @@ -39,24 +39,36 @@ func (f *filesystem) UUID() string { | ||
| func filesystem2_0(source map[string]interface{}) (*filesystem, error) { | ||
| fields := schema.Fields{ | ||
| "fstype": schema.String(), | ||
| - "mount_point": schema.String(), | ||
| - "label": schema.String(), | ||
| + "mount_point": schema.OneOf(schema.Nil(""), schema.String()), |
babbageclunk
Apr 28, 2016
•
Edited 1 time
-
babbageclunk
Apr 28, 2016
Member
-
Apr 28, 2016
Do you need the schema.OneOfs here if you're putting in defaults below? Or is it that they're sometimes null in the JSON?
voidspace
Apr 28, 2016
Contributor
It is needed if the value is nil it fails the schema check - even with a default. The default handles it being missing.
dimitern
Apr 28, 2016
Contributor
Yes, the defaults are applied only after coercing the json blob to the field map.
|
LGTM |
|
$$merge$$ |
|
Status: merge request accepted. Url: http://juju-ci.vapour.ws:8080/job/github-merge-juju-gomaasapi |
voidspace commentedApr 28, 2016
Fixes https://bugs.launchpad.net/juju-core/+bug/1575808