md-chips causes stack overflow when data objects have circular references

[rich-j]

The <md-chips> and <md-contact-chips> directives can cause a stack overflow when the data objects have a circular reference. This worked up until RC2 when this fix(md-chips): appendChip disallows identical objects #4479 changed MdChipsCtrl.prototype.appendChip by adding a call to angular.equals() which doesn't support circular references. Here is a codepen (http://codepen.io/rich-j/pen/RWvymm?editors=101) that shows the issue. Try adding another "person" to the contact chips.

Angular's equals() function has several unimplemented requests for circular reference support:

• Make angular.equals support objects with circular references #7839
• Bug in angular.equals following #7618 #7724
• making the equals method work when the obj graph has circular refs #9762
• ...and more

Each "person" in our system is a single object that has references to related objects (e.g. parent/child, owner/member). We would like to pass these "person" instances directly to <md-contact-chips>. The Angular equals() function does work for object equality (i.e. same object references) however for unequal objects it can get stuck in a cycle since it unfortunately implements a depth first search on object properties.

[topherfangio]

Just brainstorming a bit; perhaps we should offer a way to provide a custom equals function?

@robertmesserle Any thoughts?

[robertmesserle]

Hm, that could work. We could also look for circular references when
iterating through objects. Probably a good idea to do both.

On Tue, Dec 1, 2015 at 2:49 PM, Topher Fangio notifications@github.com
wrote:

Just brainstorming a bit; perhaps we should offer a way to provide a
custom equals function?

@robertmesserle https://github.com/robertmesserle Any thoughts?

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