On Nov 17, 7:37 pm, abusiek <[EMAIL PROTECTED]> wrote:
> On Nov 17, 8:43 am, Daniel Bush <[EMAIL PROTECTED]> wrote:
>
>
>
> > On Nov 17, 5:45 pm, abusiek <[EMAIL PROTECTED]> wrote:
>
> > > Hi!
>
> > > I'm struggling with this for a while and i'm new to rails so it's
> > > quite frustrating ;)
>
> > > I need to create new model object based on old one with only few
> > > changes.
>
> > > I have desings -> has many -> lines -> has_many -> fields
>
> > > I've got input from user in array like this:
>
> > > field =>[
> > > line_id =>[ fiel_id => field_value]
> > > ]
>
> > > so I iterate:
>
> > > input[:field].each do |line_id, line|
> > > line.each do |field_id, field_value|
> > > design.lines.find(line_id).fields.find(field_id).value =
> > > field_value
> > > design.lines.find(line_id).fields.find(field_id).something =
> > > field_value
> > > end
> > > end
>
> > You're finding stuff and assigning new values to what was found but
> > not saving these changes back to the db as far as I can tell here.
> > Retrieve the field once
> > field=design.lines.find(line_id).fields.find(field_id)
> > update its values and then save it
> > field.something = ...
> > field.save (or field.save!)
> > You're not creating anything new, just updating old.
>
> > If you want a new field, you'll need to create it:
> > design.lines.find(line_id).fields.push(Field.new({hash-of-
> > attributes}))
> > This will add a new field to design's line with line_id.
>
> > You could probably do something like
> > new_field=Field.new(field.attributes)
> > to create a new field with the same attributes as the existing
> > 'field', alter
> > its values as required and then push it onto the fields collection:
> > design.lines.find(line_id).fields.push(Field.new(new_field))
>
> > Be careful with names like 'field' - I don't know if they'll clash
> > with rails names.
> > Maybe also consider not chaining all those 'finds' together in one
> > line.
> > Find each thing and store it in a local variable or an instance
> > variable so
> > you won't have to get it again during the action.
>
> > --
> > Daniel Bush
>
> I followed your suggestion and write this code:
>
> 1 new_design = Design.new design.attributes
There's actually a 'clone' method which is probably better than what I
suggested before.
new_design = design.clone
But don't forget that you'll need to save it at some point.
> 2 design.background.colour_id = 123
> 3 new_design.background = Background.new
> design.background.attributes
> 4 lines = design.lines
> 5 for line in lines
> 6 new_line = Line.new line.attributes
> 7 fields = line.fields
> 8 for field in fields
> 9 field.value = input_data[:field][line.id][field.id]
> 10 new_field = Field.new field.attributes
> 11 new_line.fields.push(new_field)
> 12 end
> 13 new_design.lines.push(new_line)
> 14 end
>
> and now I'v got error that i have nil object in line 5, 8, 9 so it'
> seems that rails think's design has no lines.
>
I'm guessing it's line 9 and it has something to do with input_data
[:field] or input_data[:field][line.id] that's returning nil. 5 and 8
are just part of the looping which means there are lines and each line
does have fields.
You could compress your code a little eg
design.lines.each do |line|
new_line = line.clone
...
line.fields.each do |field|
...
end
end
I didn't mean to break everything up into separate assignments;
whatever you think is best.
--
Daniel Bush
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