Rich Collins successfully answered Vishwajith's question:

I am new to ruby on rails and am writing a simple database application...

I have people table and languages table...
they have m:n relationship using languages_people table [ has_and_belongs_to_many ]

now i was able to access all langs for a person using just
person1.languages [ array of language]

i have displayed it to front end ... which will be edited and sent back to the controller...

here i need to update the languages of that person....

i dont know how to do it...

i tried to delete all previous languages and then addnew all of them ...
but was not able to...

as i am very new to this framework, i dont have a clue as to what to do...
After reading the features offered by ruby on rails I am very much sure that there is a simple and easy way to do this ....

can anyone help me.... giving me the syntax to delete all languages corresponding to a person , and adding languages into it will be great... [ if there is a better method plz let me know..]

when i tried to add them using [ here i have copied all langs from frontend to temp_langs]

for lang in temp_langs
@person.languages << Language.new( :name => lang )
end

it created new enteries in languages table and then added into relation...
which is not what i want...
i dont want to add a new entry into languages table ...
i want to add an entry only in the languages_people table

plz...

awaiting your response...

People succeed in answering Vishwajith's questions 50% of the time (1 success in 2 attempts).

Answers by: Rich Collins

Rich Collins's Answer:

Reply by Rich Collins 729 days ago

@person.languages = array_of_language_objects

This will remove the old entries from the join table and add new ones. The former language objects will not be deleted.

If the language objects are new records, they will be saved to the languages table first.

Reply by Vishwajith 729 days ago

wow... thats easier than i thought..
thanx a lot..

Chat Conversation 729 days ago

hi Rich Collins at 9:57 PM on Wednesday August 30th, 2006
sorry I was away from my computer Rich Collins at 9:57 PM on Wednesday August 30th, 2006
are you there? Rich Collins at 9:57 PM on Wednesday August 30th, 2006
hi collins.. Vishwajith at 9:58 PM on Wednesday August 30th, 2006
i just had one more query... Vishwajith at 9:58 PM on Wednesday August 30th, 2006

Reply by Rich Collins 729 days ago

Sorry I missed you - I was not at my computer - I will be online for a few more minutes if you would like to chat.

Chat Conversation 729 days ago

if i create an array of langs and assign it to person.languages, Vishwajith at 9:58 PM on Wednesday August 30th, 2006
will it check for the existance of the lang b4??.. Vishwajith at 9:58 PM on Wednesday August 30th, 2006
say vishwa has 2 langs english and french Vishwajith at 9:59 PM on Wednesday August 30th, 2006
if i assign vishwa.languages = array with ( english , spanish ) Vishwajith at 9:59 PM on Wednesday August 30th, 2006
both english and spanish created by Language.new method... Vishwajith at 10:00 PM on Wednesday August 30th, 2006
what will happen??? ... Vishwajith at 10:00 PM on Wednesday August 30th, 2006
just curious about the above .... actually i implemented your answer and my program is working fine... thanx again.. Vishwajith at 10:01 PM on Wednesday August 30th, 2006

Reply by Vishwajith 729 days ago

actually i implemented your answer and my program is working fine... thanx again..

i just had one more query...

if i create an array of langs and assign it to person.languages,

should the array be generated from Language.new or Language.find_by_name ???

say vishwa has 2 langs english and french [ both in the join table ]
if i assign vishwa.languages = array with ( english , spanish ) both english and spanish created by Language.new method...

will it work... or should i create the array using Language.find_by_name method..

Chat Conversation 729 days ago

hi Rich Collins at 10:09 PM on Wednesday August 30th, 2006
ok let me read your messages Rich Collins at 10:10 PM on Wednesday August 30th, 2006
you will have to check to make sure that they do not already exist Rich Collins at 10:10 PM on Wednesday August 30th, 2006
so Rich Collins at 10:10 PM on Wednesday August 30th, 2006
I suggest you use the find_by method first Rich Collins at 10:10 PM on Wednesday August 30th, 2006
some_language = Language.find_by_name(the_name) || Language.create(:name => the_name) Rich Collins at 10:11 PM on Wednesday August 30th, 2006
that will either find an existing language with name the_name Rich Collins at 10:11 PM on Wednesday August 30th, 2006
or create a new one if it does not exist Rich Collins at 10:11 PM on Wednesday August 30th, 2006
ok I seem to have missed you Rich Collins at 10:12 PM on Wednesday August 30th, 2006
good luck~ Rich Collins at 10:12 PM on Wednesday August 30th, 2006
I am going to sleep now - I will be back online in the morning Rich Collins at 10:12 PM on Wednesday August 30th, 2006

Reply by Vishwajith 729 days ago

ok all right...
i was using guruza for the first time..
so didnt really know how to use chat..
so had that problem... :)
thanx a lot...