Dynamic form for .csv import (change dropdown2 based on dropdown1 selection)

Anvil Q&A
1

Am trying to create a dynamic form that allows users to upload a .csv file & then nominate the data type & format for each column, e.g. if the column contains Date data, user selects ‘Date’ from one dropdown and then the specific date format from another.

A dynamic form is preferred since the number of columns / items per row can vary as can the order, i.e. one .csv might be category/item/date, another might be date/category/item etc. etc. and can also contain a bunch of columns we just want to ignore.

Examples:

  1. British/American day & month formats are different by convention
  2. .csv output format varies per software package; some put the date column first, some will put it last
  3. Multiple date fields / multiple category fields - such as two or more date fields - I’d like to flexibility to select one date column to start with, and then choose another later.
  4. point cloud data XYZ RGB (coordinates & colour)

Here’s some simplified code of how far I’ve got (not very):

  def import_form (self):  
    fp = FlowPanel()
    
    #  add dropdown to nominate data type
    lp = LinearPanel()
    dd1 = DropDown(items=['Item Name', 'Date', 'Category'], placeholder='Ignore', include_placeholder=True)
    dd1.set_event_handler("change", self.dd1_state)
    lp.add_component(dd1)
    
    # second dropdown placeholder - add dd2.items later based on dd1 (how?)
    dd2 = DropDown()
    lp.add_component(dd2)
    
    #### 5-10 rows of data ####
    
    # add the linear panel to the flow panel
    fp.add_component(lp)
        
    # repeat for each column of data
    # linear panels contain the columns, flow panel controls left-to-right layout
    
  def dd1_state(self, sender,**event_args):
    # user selections 
    selection = sender.selected_value

No clone to share (yet). Any idea how I can use the selected value of a specific dd1 to change what is shown on dd2? I’ve read quite a bit about the use of tags, but I’m not sure that is the way to go here.

I’m not adverse to a strict column sequence and data format if this is what’s ultimately needed (i.e. sort it all out in excel first), but I thought I’d try and and offer something a bit cleverer…

2

I think the recommended way is to use a repeating panel rather than code to create the components, so you can still make use of the visual editor.

But if you want to go this way, you’ll want to add the components as form attributes so you can more easily reference them in code elsewhere in the form, rather than only giving them local names within the scope of the import_form method: e.g. self.dd1 = DropDown(...)

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