Two step selection to make a single item

Question

The application I'm creating deals with maintenance issues allowing a user to report a defect and notify the people responsible for looking at the problem. Think of the application as performing maintenance on 'parts' of a car, but those parts requiring different 'trades' to fix or manufacture them. ie. The auto electrician for the electrics of the car, but also the manufacturer of the electric components.

I'm trying to find an intuitive way of letting the user know that once they have selected the 'part' they then also need to select the 'trade or trades' associated with that part also.

Here is the mockup for reference

The 'parts' list is huge, comparitive to all the parts contained within all cars (so hundreds of thousands potentially). So I have used a miller column style (not tree view)to allow for the size - this is not the issue (unless you have a better suggestion feel free!) then I have used an add button that adds the selection to a collection box, that you can then again select the item and add a trade. The trades list is small, only about 15 maximum, depending on the part selected.

I'm having trouble displaying to the user that they have to perform this 2 step process in order to make the selection complete as a part with trades. At the moment in my mock up it is too arbitrary and I'd like it to be more obvious.

Also a trade can be assigned at any level, meaning it can be assigned to the whole engine (Parent), or just the spark plug within the engine(3rd child down).

Any suggestions, mock ups or useful information would be much appreciated.

Thank you.

Answer 1

The only thing I can think of would be for each level you click if the item in that level had options for trade the item would expand to show the trade options which they could check to assign that trade to that item.

So for example:

Parent1...........|........Child1…….....|.…..2nd Child1

Parent2..........|........Child2.............|............_Trade1

...._Trade1.......|........Child3............|.......2nd Child2

...._Trade2.......|..........._Trade1.......|......2nd Child3

Parent3............|............_Trade2.......|..... 2nd Child4

Parent4...........|.........Child4.............|..... 2nd Child5

Answer 2

Add one more column at the bottom level which contains trades for selected item.

Update

This allows making all selections in one step.

Answer 3

If you're confident there won't be too many trades per part, perhaps you could replace the "add part" button with dynamically changing buttons that say something to the effect of "Add Part and Notify name". Then, in the list of what's already been added, have a small button for each item that says "Also notify..." and allows additional trades to be notified as needed.

Answer 4

Make the first element of each column Add part and when you hover it you'll get a column with checkboxes for the 15 trades and a confirm & add at the end.

Another option for the Add Part hover would be to have the 15 trades come out of it and then when you hover a trade another 15 come ot of it, and the part is added after you've selected its trades.

I created a short example, part 1 shows the first method and the second method is in part 2. You can check it out here: http://jsfiddle.net/GGSUs/