how do I do a find by id if it exists, otherwise do a find_or_initialize_by_columname(params[:somevalue])

I am trying to allow folks to update records directly if they know the id or to put in name/address type of information and it will find the right record or create a new one if it doesn't exist.

@donor = Donor.find_or_initialize_by_company_and_prefix1_and_first_name1_and_last_name1_and_address1(params[:donor])

The above works just fine as long as the entered record contains all the necessary columns (which it will if I am reading this information in via a csv file.)

But now I would like to offer the option of ONLY including an ID and using that if it does exist in the database. If it doesn't, I would run the above statement to find by those columns or create a new record.

My controller is as follows:

      def create
        # need to find donor by id if given, else use find_or_create_by_blahblahblah

        @donor = Donor.find_or_initialize_by_company_and_prefix1_and_first_name1_and_last_name1_and_address1(params[:donor])


        if @donor.new_record?   
          @donor.save
          respond_to do |format|
            if @donor.save
              format.html { redirect_to @donor, notice: 'Donor was successfully created.' }
              format.json { render json: @donor, status: :created, location: @donor }
            else
              format.html { render action: "new" }
              format.json { render json: @donor.errors, status: :unprocessable_entity }
            end
          end    
        else
          respond_to do |format|
            if @donor.save
              format.html { redirect_to @donor, notice: 'Donor already exists.  Please edit donor if needed.'}
              format.json { render json: @dono开发者_如何学编程r, status: :created, location: @donor }
            else
              format.html { render action: "new" }
              format.json { render json: @donor.errors, status: :unprocessable_entity }
            end
          end 
        end   

      end

I am having trouble finding what to do if an ID is supplied to check it.

I tried something like:

@donor = Donor.find_by_id(params[:donor])
if !@donor
   @donor = Donor.find_or_initialize_by_all_those_columns(params[:donor])
end

but this gives me an error if I put data in, say for example, the company field instead of only the ID field.

I am sure there is a slick way to do this that I just haven't seen yet. Any help on it would be appreciated.

Try this:

unless @donor = Donor.find_by_id(params[:donor][:id]) // returns `nil` if record not found
    @donor = Donor.find_or_initialize_by_all_those_columns(params[:donor])
end

@donor.new_record? ...

The first line looks for a record with the ID passed in. If it returns a record, then @donor is set to that record and the block is not run. If not, then it will return nil (using find_by_id() instead of find() is important for this reason, because find() raises an error if no record is found), and the block will be run, setting @donor to a record (new or not) with the params.

Hopefully this answers your question.

If the record already exists you would typically route the form submission to the update action of your controller.

Nevertheless, if you want to handle the situation in the create action you simply need to know which parameter has the donor id. I'll take a guess and say that it might params[:donor][:id]. If that's the case then this would work:

@donor = Donor.find_by_id(params[:donor][:id])

Take a look at your form parameters to find out the correct name.