Adding custom fields dynamically to a model

Rails
1

I have a model called List which has many records

class List

has_many :records

end

class Record

end

The table Record has 2 permanent fields: name, email. Besides these 2
fields, for each List a Record can have ‘n’ custom fields.

for example: for list1 I add address(text), dob(date) as custom
fields. then while adding records to list one, each record can have
values for address and dob.

Is there any activerecord plugin which provides this type of
functionality. Else could you share your thoughts on how to model
this.

Thanks in advance, Pankaj

2

Are you talking about a dynamic view here?
I.E the table ‘records’ has 10 fields, but for this particular list
only 3 of them are going to be used?

BTW, if your table is called “records” it will cause problems for
ActiveRecords finds. I suggest you rename it to something else.

3

pankaj wrote:

I have a model called List which has many records

class List

has_many :records

end

class Record

end

The table Record has 2 permanent fields: name, email. Besides these 2
fields, for each List a Record can have ‘n’ custom fields.

for example: for list1 I add address(text), dob(date) as custom
fields. then while adding records to list one, each record can have
values for address and dob.

Is there any activerecord plugin which provides this type of
functionality. Else could you share your thoughts on how to model
this.

If there’s really no common schema beyond name and e-mail, then you have
several options to play with:

  • Use a serialized hash for the “extra” fields.
  • Put the “extra” fields in some other table and use associations.
  • Use a schemaless database such as MongoDB.

This is not something that SQL databases do easily.

Thanks in advance, Pankaj

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

4

Marnen Laibow-Koser wrote:

  • Put the “extra” fields in some other table and use associations.

You could implement a simple “key - key value” model, and tie that
back to the record and list since it seems that you’ll have different
custom fields per list.

Perhaps the “list” model has an associated list of custom field
definitions (name, type, size, etc?)

Each “record” for the list finds out what its list’s custom fields are,
then maintains values for those in its associated table of ‘custom field
values’

Or something like that…