can't pass d3 selection to chart constructor

[rjmorris]

The documentation says the parent argument for dc chart constructors can be:

Any valid d3 single selector specifying a dom block element such as a div; or a dom element or d3 selection.

However, passing in a d3 selection doesn't work for me. Here's an illustration: http://jsfiddle.net/rjmorris/uv28k803. (This example uses the stable version of dc, but the same thing happens with the latest 2.0.0 beta.) Examining the source, it appears that in baseChart.anchor(), dc is select()ing my selection under the assumption that it's a selector string or a dom element. This causes an error later (TypeError: node.getAttribute is not a function) when d3 tries to add a class to the parent div.

[gordonwoodhull]

Thanks for reporting, @rjmorris.

At some point I had the impression that d3.select was idempotent, that selecting a selection returns the selection. But that does not seem to be the case. The implementation should either detect this, or the documentation should be fixed.

Obviously the workaround is to pass selection.node() instead.

[gordonwoodhull]

So, yeah, superficially d3.select on a d3 selection appears to work, because d3 assumes the object is an HTML element and wraps it in another selection-array. Then stuff breaks later on.

I'm adding something to detect d3 selections based on what methods they support, and treat them appropriately.

[rjmorris]

Great! Thanks for looking into this.

[gordonwoodhull]

Closed (a few weeks ago) by 4d68611

[gordonwoodhull]

For closure and rationale: d3/d3-selection#76

Fair enough, and that shows the right way to test if something is a selection (instanceof selection), which we should use.