Ruby on Rails

On May 26, 2014, at 8:38 AM, Ronald Fischer wrote:

> I thought this is an easy one, but: I have created a record, and later
> would like to retrieve it again.
>
> Here is an excerpt of my schema:
>
> create_table "dicts", force: true do |t|
> t.string "dictname"
> ...
> end
>
> My model ensures that dictname is unique:
>
> validates :dictname,
> presence: true,
> length: { minimum: 3 },
> format: { with: /\A\D/ },
> uniqueness: true
>
> In my controller, I tried this to fetch a Dict object, when the value
> for the :dictname field is stored in variable dict_name:
>
> if Dict.exists?(:dictname => dict_name)
> logger.debug('found dictionary with name '+dict_name)
> dictid=Dict.where(:dictname => dict_name).select('id').first.id
> logger.debug('dictid='+dictid.inspect)
> @dict=Dict.find(dictid)
>
> However, the line to calculate dictid fails with
>
> TypeError (can't cast Hash to integer)
>
> which would suggest that the hash argument to the 'where' method is
> unexpected. But this can't really be, can it?
>
> So, my questions:
>
> - Why do I get this error?
>
> - How do I fix it?
>
> - The whole procedure to get at my Dict record, looks unnecessarily
> convoluted to me. Isn't there an easier way to do it?

ActiveRecord already has a finder that can do all this in one line:

Dict.first_or_create(url: params[:dictname])

Assuming that's the only thing needed to create or find an existing Dict, you should be all good there.

Walter


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