Arguments error while calling function

Question

I am getting ArgumentError in ArticlesController#scrape on def extract_Articles(source_url:, source_type:, source_key:)

I am extracting the list of articles from different sources, and returning it back to my controller function.

class ArticleController

  def Scrape
      @get_Articles = Source.new
      articles = @get_Articles.get_Articles
      ...
  end
end

class Source
  def get_Articles
    @articles = Array.new
    @articles = extract_Articles('url1','rss',nil)
    @articles = extract_Articles('url2','rss',nil)
    @articles = extract_Articles('url3','rss',nil)
    @articles = extract_Articles('url4','json','some-value')

  end  
  def extract_Articles(soruce_url:, url_type:, source_key:)
    ...
  end
end

Could somebody let me know of this problem? Surprisingly I am not sure why this is not working actually!

Small point, ruby method naming is typically all lower case. Underscores are used instead of CamelCase. — AJFaraday
– AJFaraday, Commented Sep 17, 2015 at 13:15
I think we might need some more information, the routes for ArticleController would be helpful, as well as the log when this error is being called. This gives us a much better chance to answer appropriately. — AJFaraday
– AJFaraday, Commented Sep 17, 2015 at 13:16

ndnenkov · Accepted Answer · 2015-09-17 13:14:44Z

3

The problem is that your method is defined to use named arguments, but you try to call it with positional ones.

Either define it with positional arguments:

def extract_Articles(soruce_url, url_type, source_key)
  # ...
end

Or invoke it with named ones:

@articles = extract_Articles(soruce_url: 'url1', url_type: 'rss', source_key: nil)

edited Sep 17, 2015 at 13:14

answered Sep 17, 2015 at 13:07

ndnenkov

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Comments

pangpang · Accepted Answer · 2015-09-17 13:22:59Z

2

the method arguments should be variables, and you also can set the default value for arguments.

def extract_Articles(soruce_url, url_type, source_key=nil)
    ...
end

@articles = extract_Articles('url1','rss')
@articles = extract_Articles('url4','json','some-value')

You can get more detail info from here

answered Sep 17, 2015 at 13:22

pangpang

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Comments

Zahid · Accepted Answer · 2015-09-17 15:40:27Z

2

Method arguments cannot be symbols they need to be variables so that when function is called by passing values those variables will have that value.

Okay I have read about keyword params, so here is my updated answer

you need to pass params like this

@articles = extract_Articles(soruce_url: 'url1',url_type: 'rss',source_key:nil)

edited Sep 17, 2015 at 15:40

answered Sep 17, 2015 at 14:07

Zahid

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2 Comments

ndnenkov Over a year ago

I would suggest you to read about keyword arguments.

Zahid Over a year ago

Thanks I surely didn't know that

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