Dynamically iterate around a table's columns (using content_columns?) to save some fields

Hi there, I was trying to make some DRY code in the 'edit' controller so it will check for every single column and if it is empty, to write something like '[Undefined]' in it's place. The thing is didn't want to make the code static and have to rewrite it every time i change the table it uses, so i thought that this (or something like this) would work:

  def edit     @post = Post.find(params[:id])     for column in Post.content_columns       if @post.column = ''         @post.column = "[#{column.human_name} not set]"       end     end   end

Also, i found weird the fact that (in other cases not here - as this code won't work) if i use the condition @post.<some_column_here> = nil doesn't seem to work (when the selected column is null, meaning not set in model creation). Instead i used the = '' (an empty sting) and worked ok until now, but i believe that this is reaaally bad coding and a hole of bugs in the future... Isn't there any better way to make this work?

Any help would be highly appreciated :slight_smile:

P.S. : As you can see (probably) i'm pretty noob in rails when it comes to practical experience, although i've read a lot documentation and books about rails (and ruby).

Also, i found weird the fact that (in other cases not here - as this code won't work) if i use the condition @post.<some_column_here> = nil doesn't seem to work (when the selected column is null, meaning not set in model creation). Instead i used the = '' (an empty sting) and worked ok until now, but i believe that this is reaaally bad coding and a hole of bugs in the future... Isn't there any better way to make this work?

i found out why this is happening so nevermind about this one. stupid scaffolding....

Glad you figured it out. Couple thoughts to chew on though:

"@post.column" would not use the contents of the variable "column" to look for a column with that name... it tries to call a "column" method on the object @post.

Also, the logic determining whether a model gets some default value should really be in the model.... and then you can use the protected "write_attribute" method, perhaps in one of the lifecycle callbacks.

b

demisone wrote:

I have been trying to do the same thing. What I ended doing is the following. I would be interested to find out if I have offended many guidelines in doing so.

I moved the code to loop on the table column in the model itself and used the @attributes hash directly to access the columns.

['col1','col2','col3'].each {|col| @attributes[col]=params[col]}

I never got something like self.#{col} to work.

For now, I am happy with using @attributes[var]. Does anyone have a better solution?

J-F (Ottawa,Canada)

I moved the code to loop on the table column in the model itself and used the @attributes hash directly to access the columns.

['col1','col2','col3'].each {|col| @attributes[col]=params[col]}

You mean you write ['col1',...,] statically? That's no good for what i wanted to to... :frowning:

I never got something like self.#{col} to work.

Yeah, me neither :smiley:

For now, I am happy with using @attributes[var]. Does anyone have a better solution?

I'm not aware of this (i think), gonna check it out...

Thanks for sharing your thoughts anyway :slight_smile:

-Nikos D (Athens, Greece)

I think what you want to code is :

     post[column]

This uses the accessor method and treats 'column' as a variable and thus gets the correct (dynamic) column that you want to process.

HTH...jon