JSON Array parsing in ROR

Question

I am getting JSON in following format from my Android application

{"list":[{"itemno":"w01","name":"t01","amount":"120","status":"done"},{"itemno":"w02","name":"t02","amount":"120","status":"done"},{"itemno":"w03","name":"t03,"amount":"120","status":"done""}]}

I need to parse this to insert into mysql table "list". I modified "create" code in my controller as below

def create
lists = params[:list].collect{|key,list_attributes| List.new(list_attributes) }
    all_list_valid = true
    lists.each_with_index do |list,index|
     unless list.valid?
      all_list_valid = false
      invalid_list = lists[index]
     end
    end

    if all_list_valid
     @lists = []
     lists.each do |list|
       list.save
       @lists << list
     end
      format.html { redirect_to @list, notice: 'List was successfully created.' }
      format.json { render json: @list, status: :created, location: @list } 
    else
      format.html { render action: "new" }
      format.json { render json: @list.errors, status: :unprocessable_entity }
    end
  end

But its unable to parse the JSON, so not calling the create method. I am very new to ROR and tried above code too from web. Not sure if the entire piece above is incorrect or I am missing something. Please advise. Thanks.

MrYoshiji · Accepted Answer · 2013-08-12 14:05:44Z

3

Also, you can refactor your code a little bit:

# This part of code
@lists = []
lists.each do |list|
  list.save
  @lists << list
end
# Can be shortened:
lists.map(&:save)
@lists = lists

The whole action can be refactored like this:

def create
  lists = params[:list].each{ |list_attributes| List.new(list_attributes) }
  valid, not_valid = lists.partition{ |list| list.valid? }

  if not_valid.blank?
    lists.map(&:save)
    @lists = lists
    format.html { redirect_to @list, notice: 'List was successfully created.' }
    format.json { render json: @list, status: :created, location: @list }
  else
    format.html { render action: "new" }
    format.json { render json: @list.errors, status: :unprocessable_entity }
  end
end

edited Aug 12, 2013 at 14:05

answered Aug 12, 2013 at 13:28

MrYoshiji

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6 Comments

Gaurav Over a year ago

Thanks. Tried with suggested changes but still getting error "TypeError (no implicit conversion of Array into String):"

MrYoshiji Over a year ago

From what line, what method that it is raised? If it is from the JSON.decode, it means your params[:list] are already converted into Array (of Hashes).

Gaurav Over a year ago

Yes its from JSON.decode. If its already converted into Array, could you please advise what to do next. I am totally new to ROR so bit confused how to proceed. Thanks

Gaurav Over a year ago

Thanks a lot again. I tried with updated answer and its parsing the JSON object into 3 and creating 3 Insert Statements. But the values are populating as NULL. The Insert statement is taking values as NULL. INSERT INTO lists (amount, itemno, name, status) VALUES (NULL, NULL, NULL, NULL)

MrYoshiji Over a year ago

Okay then try to see the output of lists.first to see how the data is formated and if it matches the Model's attributes

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