如何我插入一个数组使用ActiveRecord一个PostgreSQL表？

Question

我active_record设置为使用PostgreSQL数据库。其中一列是character varying[]（基本上是VARCHAR数组）。

无论如何，我的导入例程然后读取制表符分隔的文本文件，并插入记录。一切都很好，直到我得到一个数组。应该转换为数组的列以逗号分隔。但该行本身是制表符分隔的。

我导入看起来像数据的样品（制表符分隔）：

Col1  Col2  Col3     Col4 
---------------------------------------------- 
Apple  Pear  Sweet,Round,Green  Fruit 

COL3导入等（红宝石）：col3.split(/,/)这使我在红宝石阵列。但active_record弹出：

PG::Error: ERROR: array value must start with "{" or dimension information (ActiveRecord::StatementInvalid)

如何正确插入该列？
此外，有时，COL3将是NULL。

Answer 1

我可以使用下面的Ruby代码中插入：

alternatenames = '{' + s[3].split(/,/).map {|n| '"' + n + '"'}.join(",") + '}' 

Answer 2

检查Postgres的这个文档：http://www.postgresql.org/docs/9.2/static/arrays.html

可以使用像数组实例化一个模型[：我，：符号]或[“我的”，“字符串”]，但它（在我的经验，并形成什么，似乎在docs）将保存元素的字符串。

Search.create(tokens: [{hash: 'value'}, {test: "fails"}]) 
=> TypeError: can't cast Hash to string 

凡为：

[15] pry(main)> Search.create(tokens: [:G, :F]) 
=> #<Search id: 78, tokens: [:G, :F], created_at: "2013-12-18 06:29:36", updated_at: "2013-12-18 06:29:36"> 
[16] pry(main)> Search.last 
=> #<Search id: 78, tokens: ["G", "F"], created_at: "2013-12-18 06:29:36", updated_at: "2013-12-18 06:29:36"> 

在我的测试中，我有一个的搜索引擎，搜索和期限。

class SearchEngine < ActiveRecord::Base 
    has_and_belongs_to_many :terms 
    has_many :searches, through: :terms 
end 

class Term < ActiveRecord::Base 
    has_and_belongs_to_many :searches 
    has_and_belongs_to_many :searche_engines 
end 

class Search < ActiveRecord::Base 
    has_many :rankings 
    has_many :results, through: :rankings 
    has_and_belongs_to_many :terms 
    has_many :search_engines, through :terms 
end 


# These work: 
# these next two are the way postgrespl says to query against the array. You get the 
Search.where(tokens: '{A,B}') 
Search.where(tokens: '{C,D}').first_or_create 

[3] pry(main)> Search.where(tokens: ['C','D']).first 
ActiveRecord::StatementInvalid: PG::InvalidTextRepresentation: ERROR: array value must start with "{" or dimension information 

[4] pry(main)> Search.where(tokens: '{C,D}').first 
=> #<Search id: 77, tokens: ["C", "D"], created_at: "2013-12-18 06:27:24", updated_at: "2013-12-18 06:27:24"> 

term = "accident" 
Search.where("? = ANY (tokens)", term).first 
=> #<Search id: 8, tokens: ["accident", "prevention", "safety"], created_at: "2013-12-18 07:48:13", updated_at: "2013-12-18 07:48:13"> 
Search.create(tokens: [:Aortic, :Any, :Other, :Elements]) 
Search.where("'Aortic' = ANY (tokens)").first 
Parent.first.first_relationships.first.second_.where("'smelly' = ANY (tokens)").first 
# The next one will create one with an empty array for tokens and push it into Term.searches anyway. Same thing with 'smelly' 
Term.first.searches.where("':smelly' = ANY (tokens)").first_or_create do |s| Term.first.searches << s 
end 

# These error 
Search.where(tokens: "Aortic").first 
Search.where(tokens: [:Aortic, :Any, :Other, :Elements]).first 

另外，如果您有嵌套数组，你可以做一个地方搜索与此：“{{1,2,3}，{4,5,6}，{7,8,9}} '查找具有列值的行[[1,2,3]，[4,5,6]，[7,8,9]]