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Asked: 2026-05-24T04:26:56+00:00

Two models: category has_many: components component belongs_to: category The CATEGORY table defines variable names

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Two models:

category has_many: components
component belongs_to: category

The CATEGORY table defines variable names for different component types:

TYPE, VAR1, VAR2, VAR3, ...

Insulator, Voltage, Height, Material, ...

Current Transformer, Voltage, Ratio, Indoor, ...

In the NEW/EDIT views for the COMPONENT model, the user will first section the CATEGORY from a drop-down list. Based on the CATEGORY selected the column headings and field labels in the form(s) need to dynamically update to indicate the variable names associated with the selected CATEGORY.

i.e. IF the user selects CATEGORY = Insulator THEN the field labels for VAR1 … VAR3 are Voltage, Height, Material, etc.

I assume this will be controlled in the _form.html.erb of a typical scaffold. I am looking for a recommended technique.

Thanks in advance any information.

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1 Answer

  1. Editorial Team

    Changing a form in response to a user selecting a different option in a select tag is probably best done by Javascript. This allows for execution on the client side, which will be faster than a trip back to the server.

    I would recommend placing the different form fields inside a div tag that is hidden when the page loads. Each of the combinations of categories can be toggled to show in the form by binding to the Javscript onChange event on the select tag.

    Here is more information on the select tag: http://www.w3schools.com/jsref/event_onchange.asp

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