Cannot extract data from a hash












0















I have an array of hashes:



array_hash = [{product: 'A', qty: 1}, {product: 'B', qty: 2}]


I want to get the value of the first key "product".



I get the expected hash with this code:



get_first_hash = array_hash[0]

# => {product: 'A', qty: 1}


However, this code returns nil:



get_value = get_first_hash['product']

# => nil


I hope someones can tell me about this.






ruby hash







share|improve this question




















  • 1





    This is because :product == 'product' #=> false

    – iGian
    Nov 20 '18 at 19:23











  • Your hash does not have a key "product" (although you have key :product). Don't use (hash) literals without knowing what it means.

    – sawa
    Nov 21 '18 at 4:01


















0















I have an array of hashes:



array_hash = [{product: 'A', qty: 1}, {product: 'B', qty: 2}]


I want to get the value of the first key "product".



I get the expected hash with this code:



get_first_hash = array_hash[0]

# => {product: 'A', qty: 1}


However, this code returns nil:



get_value = get_first_hash['product']

# => nil


I hope someones can tell me about this.






ruby hash







share|improve this question




















  • 1





    This is because :product == 'product' #=> false

    – iGian
    Nov 20 '18 at 19:23











  • Your hash does not have a key "product" (although you have key :product). Don't use (hash) literals without knowing what it means.

    – sawa
    Nov 21 '18 at 4:01
















0












0








0


0






I have an array of hashes:



array_hash = [{product: 'A', qty: 1}, {product: 'B', qty: 2}]


I want to get the value of the first key "product".



I get the expected hash with this code:



get_first_hash = array_hash[0]

# => {product: 'A', qty: 1}


However, this code returns nil:



get_value = get_first_hash['product']

# => nil


I hope someones can tell me about this.






ruby hash







share|improve this question
















I have an array of hashes:



array_hash = [{product: 'A', qty: 1}, {product: 'B', qty: 2}]


I want to get the value of the first key "product".



I get the expected hash with this code:



get_first_hash = array_hash[0]

# => {product: 'A', qty: 1}


However, this code returns nil:



get_value = get_first_hash['product']

# => nil


I hope someones can tell me about this.






ruby hash




ruby hash






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 21 '18 at 3:57









sawa

131k29205303




131k29205303










asked Nov 20 '18 at 15:40









Nguyen Khoi NguyenNguyen Khoi Nguyen

64




64








  • 1





    This is because :product == 'product' #=> false

    – iGian
    Nov 20 '18 at 19:23











  • Your hash does not have a key "product" (although you have key :product). Don't use (hash) literals without knowing what it means.

    – sawa
    Nov 21 '18 at 4:01
















  • 1





    This is because :product == 'product' #=> false

    – iGian
    Nov 20 '18 at 19:23











  • Your hash does not have a key "product" (although you have key :product). Don't use (hash) literals without knowing what it means.

    – sawa
    Nov 21 '18 at 4:01










1




1





This is because :product == 'product' #=> false

– iGian
Nov 20 '18 at 19:23





This is because :product == 'product' #=> false

– iGian
Nov 20 '18 at 19:23













Your hash does not have a key "product" (although you have key :product). Don't use (hash) literals without knowing what it means.

– sawa
Nov 21 '18 at 4:01







Your hash does not have a key "product" (although you have key :product). Don't use (hash) literals without knowing what it means.

– sawa
Nov 21 '18 at 4:01














2 Answers
2






active

oldest

votes


















2














Hope this suffices!



array_hash.first[:product]



If you want the second one you just do



array_hash.second[:product]


Also, .first is just a helper for doing array_hash[0], but the issue behind you getting nil is that you need to represent it with a :symbol in Ruby






share|improve this answer
























  • Thank you for your answer. It really works for me

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46



















1














I'm guessing you're accustom to using Hash in Ruby on Rails, which subclasses the Hash class that comes with Ruby as HashWithIndifferentAccess, and you usually never forced to look at this as a developer (in Rails). It should also be noted, that Rails directly modifies Ruby's base Hash class, so you actually have a lot more available to you in Rails (or, specifically when ActiveSupport is loaded).



Ruby (pure), however doesn't mess around when it comes to keys in the hash. This allows for some powerful applications—remember, everything in Ruby is an Object.



So, 'string' and :symbol are both objects, and different objects at that. You can even use a Class as a key in your hash.



{

  Object => :object_symbol,

  Class => :class_symbol

}


So when you're trying to access values behind a key in your hash, make sure you use the exact key itself.



In your example above, you're using the symbol product as your key. Ruby uses : to denote that.



{

  product: 'A',

  qty: 1

}


This is the equivalent of saying



{

  :product => 'A',

  :qty => 1

}


So what you want to call is get_value = get_first_hash[:product]






share|improve this answer


























  • Thank you so much for your detail answer. It really works for me. Because I am a newbie in Ruby and I am trying to learn by myself so there is something I can not handle it. Thank you

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46













  • @NguyenKhoiNguyen here at Stack Overflow, we try to accept answers that have the most explanation that also addresses the question. Please consider changing your accepted answer.

    – Volte
    Nov 22 '18 at 14:52











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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes









2














Hope this suffices!



array_hash.first[:product]



If you want the second one you just do



array_hash.second[:product]


Also, .first is just a helper for doing array_hash[0], but the issue behind you getting nil is that you need to represent it with a :symbol in Ruby






share|improve this answer
























  • Thank you for your answer. It really works for me

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46
















2














Hope this suffices!



array_hash.first[:product]



If you want the second one you just do



array_hash.second[:product]


Also, .first is just a helper for doing array_hash[0], but the issue behind you getting nil is that you need to represent it with a :symbol in Ruby






share|improve this answer
























  • Thank you for your answer. It really works for me

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46














2












2








2







Hope this suffices!



array_hash.first[:product]



If you want the second one you just do



array_hash.second[:product]


Also, .first is just a helper for doing array_hash[0], but the issue behind you getting nil is that you need to represent it with a :symbol in Ruby






share|improve this answer













Hope this suffices!



array_hash.first[:product]



If you want the second one you just do



array_hash.second[:product]


Also, .first is just a helper for doing array_hash[0], but the issue behind you getting nil is that you need to represent it with a :symbol in Ruby







share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 20 '18 at 15:57









kallelundgren93kallelundgren93

1189




1189













  • Thank you for your answer. It really works for me

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46



















  • Thank you for your answer. It really works for me

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46

















Thank you for your answer. It really works for me

– Nguyen Khoi Nguyen
Nov 21 '18 at 16:46





Thank you for your answer. It really works for me

– Nguyen Khoi Nguyen
Nov 21 '18 at 16:46













1














I'm guessing you're accustom to using Hash in Ruby on Rails, which subclasses the Hash class that comes with Ruby as HashWithIndifferentAccess, and you usually never forced to look at this as a developer (in Rails). It should also be noted, that Rails directly modifies Ruby's base Hash class, so you actually have a lot more available to you in Rails (or, specifically when ActiveSupport is loaded).



Ruby (pure), however doesn't mess around when it comes to keys in the hash. This allows for some powerful applications—remember, everything in Ruby is an Object.



So, 'string' and :symbol are both objects, and different objects at that. You can even use a Class as a key in your hash.



{

  Object => :object_symbol,

  Class => :class_symbol

}


So when you're trying to access values behind a key in your hash, make sure you use the exact key itself.



In your example above, you're using the symbol product as your key. Ruby uses : to denote that.



{

  product: 'A',

  qty: 1

}


This is the equivalent of saying



{

  :product => 'A',

  :qty => 1

}


So what you want to call is get_value = get_first_hash[:product]






share|improve this answer


























  • Thank you so much for your detail answer. It really works for me. Because I am a newbie in Ruby and I am trying to learn by myself so there is something I can not handle it. Thank you

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46













  • @NguyenKhoiNguyen here at Stack Overflow, we try to accept answers that have the most explanation that also addresses the question. Please consider changing your accepted answer.

    – Volte
    Nov 22 '18 at 14:52
















1














I'm guessing you're accustom to using Hash in Ruby on Rails, which subclasses the Hash class that comes with Ruby as HashWithIndifferentAccess, and you usually never forced to look at this as a developer (in Rails). It should also be noted, that Rails directly modifies Ruby's base Hash class, so you actually have a lot more available to you in Rails (or, specifically when ActiveSupport is loaded).



Ruby (pure), however doesn't mess around when it comes to keys in the hash. This allows for some powerful applications—remember, everything in Ruby is an Object.



So, 'string' and :symbol are both objects, and different objects at that. You can even use a Class as a key in your hash.



{

  Object => :object_symbol,

  Class => :class_symbol

}


So when you're trying to access values behind a key in your hash, make sure you use the exact key itself.



In your example above, you're using the symbol product as your key. Ruby uses : to denote that.



{

  product: 'A',

  qty: 1

}


This is the equivalent of saying



{

  :product => 'A',

  :qty => 1

}


So what you want to call is get_value = get_first_hash[:product]






share|improve this answer


























  • Thank you so much for your detail answer. It really works for me. Because I am a newbie in Ruby and I am trying to learn by myself so there is something I can not handle it. Thank you

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46













  • @NguyenKhoiNguyen here at Stack Overflow, we try to accept answers that have the most explanation that also addresses the question. Please consider changing your accepted answer.

    – Volte
    Nov 22 '18 at 14:52














1












1








1







I'm guessing you're accustom to using Hash in Ruby on Rails, which subclasses the Hash class that comes with Ruby as HashWithIndifferentAccess, and you usually never forced to look at this as a developer (in Rails). It should also be noted, that Rails directly modifies Ruby's base Hash class, so you actually have a lot more available to you in Rails (or, specifically when ActiveSupport is loaded).



Ruby (pure), however doesn't mess around when it comes to keys in the hash. This allows for some powerful applications—remember, everything in Ruby is an Object.



So, 'string' and :symbol are both objects, and different objects at that. You can even use a Class as a key in your hash.



{

  Object => :object_symbol,

  Class => :class_symbol

}


So when you're trying to access values behind a key in your hash, make sure you use the exact key itself.



In your example above, you're using the symbol product as your key. Ruby uses : to denote that.



{

  product: 'A',

  qty: 1

}


This is the equivalent of saying



{

  :product => 'A',

  :qty => 1

}


So what you want to call is get_value = get_first_hash[:product]






share|improve this answer















I'm guessing you're accustom to using Hash in Ruby on Rails, which subclasses the Hash class that comes with Ruby as HashWithIndifferentAccess, and you usually never forced to look at this as a developer (in Rails). It should also be noted, that Rails directly modifies Ruby's base Hash class, so you actually have a lot more available to you in Rails (or, specifically when ActiveSupport is loaded).



Ruby (pure), however doesn't mess around when it comes to keys in the hash. This allows for some powerful applications—remember, everything in Ruby is an Object.



So, 'string' and :symbol are both objects, and different objects at that. You can even use a Class as a key in your hash.



{

  Object => :object_symbol,

  Class => :class_symbol

}


So when you're trying to access values behind a key in your hash, make sure you use the exact key itself.



In your example above, you're using the symbol product as your key. Ruby uses : to denote that.



{

  product: 'A',

  qty: 1

}


This is the equivalent of saying



{

  :product => 'A',

  :qty => 1

}


So what you want to call is get_value = get_first_hash[:product]







share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 20 '18 at 16:05

























answered Nov 20 '18 at 15:58









VolteVolte

1,5691322




1,5691322













  • Thank you so much for your detail answer. It really works for me. Because I am a newbie in Ruby and I am trying to learn by myself so there is something I can not handle it. Thank you

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46













  • @NguyenKhoiNguyen here at Stack Overflow, we try to accept answers that have the most explanation that also addresses the question. Please consider changing your accepted answer.

    – Volte
    Nov 22 '18 at 14:52



















  • Thank you so much for your detail answer. It really works for me. Because I am a newbie in Ruby and I am trying to learn by myself so there is something I can not handle it. Thank you

    – Nguyen Khoi Nguyen
    Nov 21 '18 at 16:46













  • @NguyenKhoiNguyen here at Stack Overflow, we try to accept answers that have the most explanation that also addresses the question. Please consider changing your accepted answer.

    – Volte
    Nov 22 '18 at 14:52

















Thank you so much for your detail answer. It really works for me. Because I am a newbie in Ruby and I am trying to learn by myself so there is something I can not handle it. Thank you

– Nguyen Khoi Nguyen
Nov 21 '18 at 16:46







Thank you so much for your detail answer. It really works for me. Because I am a newbie in Ruby and I am trying to learn by myself so there is something I can not handle it. Thank you

– Nguyen Khoi Nguyen
Nov 21 '18 at 16:46















@NguyenKhoiNguyen here at Stack Overflow, we try to accept answers that have the most explanation that also addresses the question. Please consider changing your accepted answer.

– Volte
Nov 22 '18 at 14:52





@NguyenKhoiNguyen here at Stack Overflow, we try to accept answers that have the most explanation that also addresses the question. Please consider changing your accepted answer.

– Volte
Nov 22 '18 at 14:52


















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