{"action":"closed","issue":{"url":"https://api.github.com/repos/canjs/canjs/issues/2117","labels_url":"https://api.github.com/repos/canjs/canjs/issues/2117/labels{/name}","comments_url":"https://api.github.com/repos/canjs/canjs/issues/2117/comments","events_url":"https://api.github.com/repos/canjs/canjs/issues/2117/events","html_url":"https://github.com/canjs/canjs/issues/2117","id":120100852,"number":2117,"title":"Binding an undefined property to a component runs the setter","user":{"login":"dylanrtt","id":11302736,"avatar_url":"https://avatars.githubusercontent.com/u/11302736?v=3","gravatar_id":"","url":"https://api.github.com/users/dylanrtt","html_url":"https://github.com/dylanrtt","followers_url":"https://api.github.com/users/dylanrtt/followers","following_url":"https://api.github.com/users/dylanrtt/following{/other_user}","gists_url":"https://api.github.com/users/dylanrtt/gists{/gist_id}","starred_url":"https://api.github.com/users/dylanrtt/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/dylanrtt/subscriptions","organizations_url":"https://api.github.com/users/dylanrtt/orgs","repos_url":"https://api.github.com/users/dylanrtt/repos","events_url":"https://api.github.com/users/dylanrtt/events{/privacy}","received_events_url":"https://api.github.com/users/dylanrtt/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/canjs/canjs/labels/Bug","name":"Bug","color":"e10c02"}],"state":"closed","locked":false,"assignee":null,"milestone":{"url":"https://api.github.com/repos/canjs/canjs/milestones/39","html_url":"https://github.com/canjs/canjs/milestones/2.3.5","labels_url":"https://api.github.com/repos/canjs/canjs/milestones/39/labels","id":1440078,"number":39,"title":"2.3.5","description":"","creator":{"login":"daffl","id":338316,"avatar_url":"https://avatars.githubusercontent.com/u/338316?v=3","gravatar_id":"","url":"https://api.github.com/users/daffl","html_url":"https://github.com/daffl","followers_url":"https://api.github.com/users/daffl/followers","following_url":"https://api.github.com/users/daffl/following{/other_user}","gists_url":"https://api.github.com/users/daffl/gists{/gist_id}","starred_url":"https://api.github.com/users/daffl/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/daffl/subscriptions","organizations_url":"https://api.github.com/users/daffl/orgs","repos_url":"https://api.github.com/users/daffl/repos","events_url":"https://api.github.com/users/daffl/events{/privacy}","received_events_url":"https://api.github.com/users/daffl/received_events","type":"User","site_admin":false},"open_issues":3,"closed_issues":2,"state":"open","created_at":"2015-12-02T17:39:03Z","updated_at":"2015-12-03T20:38:46Z","due_on":null,"closed_at":null},"comments":3,"created_at":"2015-12-03T06:05:26Z","updated_at":"2015-12-03T20:38:46Z","closed_at":"2015-12-03T20:38:46Z","body":"In the following example, if the parent `bar` is undefined, the `foo` setter will run anyway. Maybe I'm wrong, but I don't think that's the right behavior. This is new in 2.3.3 and was not happening previously. It affects both 1-way and 2-way bindings using the new syntax (old binding syntax unaffected).\r\n\r\n```html\r\n<foo-bar {foo}=\"bar\"></foo-bar>\r\n```\r\n\r\nhttp://jsbin.com/guweguqovi/edit?html,js,console\r\n\r\nI just noticed that if the parent property is defined, the setter is run twice, which is strange for a 1-way binding, right? That is also new to 2.3.3."}}