遍歷一個散列數組來創建數據導軌

Question

我有一個散列數組，我試圖種入數據庫。

shoe_array = [{:department_id=>8, :follower_id=>31}, {:department_id=>9, :follower_id=>41}, {:department_id=>4, :follower_id=>49}, {:department_id=>2, :follower_id=>58}, {:department_id=>5, :follower_id=>36}, {:department_id=>9, :follower_id=>63}, {:department_id=>2, :follower_id=>52}, {:department_id=>23, :follower_id=>26}, {:department_id=>5, :follower_id=>52}, {:department_id=>6, :follower_id=>30}] 


shoe_array.each do |n, k| 
    department_id = n, 
    follower_id = k, 
    user_id = 1 

    Relationship.create!(department_id: department_id, 
         follower_id: follower_id, 
         user_id: user_id) 
end 

我只獲得兩個department_id和follower_id空值。 user_id正在工作。

我嘗試過使用"#{n}"和"#{k}"，以獲取設置爲部門和關注者ID的關鍵值。我也試着迭代陣列上只能用.each do |a|和設置department_id: a['department_id'], follower_id a['follower_id']

如下所示：iterate through array of hashes in ruby這裏：How do I iterate over an array of hashes and return the values in a single string?

，但我只仍然得到空值。我怎樣才能將我的值存入數據庫？

Answer 1

shoe_array是哈希的數組，所以你應該遍歷每個哈希，並訪問每個鍵 - 值對：

shoe_array.each do |hash| 
    department_id = hash[:department_id] 
    follower_id = hash[:follower_id] 
    user_id  = 1 

    Relationship.create!(
    department_id: department_id, 
    follower_id: follower_id, 
    user_id:  user_id 
) 
end 

Answer 2

您的迭代更改爲

shoe_array.each do |shoe| 
    department_id = shoe[:department_id] 
    follower_id = shoe[:follower_id] 

，可以用一個例子|n, k|可能是散列或陣列數組。如果你想要走這條路線，你可以在陣列中的每個哈希調用values（假設哈希是一致的，這意味着department_id永遠是第一位follower_id之前）

ids = shoe_array.map(&:values) # [[8, 31], [9, 41], [4, 49], [2, 58], [5, 36], [9, 63], [2, 52], [23, 26], [5, 52], [6, 30]] 

然後，你可以使用舊代碼或重構爲

ids.each do |department_id, follower_id| 
    Relationship.create!(
    department_id: department_id, 
    follower_id: follower_id, 
    user_id: 1 
) 
end 

請注意，雖然您正在遍歷數組兩次，並且與第一次相比效率較低。

UPDATE

另一種選擇是使用數組元素是。

shoe_array.each do |attributes| 
    relationship = Relationship.new(attributes) 
    relationship.user_id = 1 
    relationship.save! 
end 

Answer 3

據的文檔，你可以create記錄從哈希的數組：

下面應該工作（可以使用create!以及create）

shoe_array = [{:department_id=>8, :follower_id=>31}, {:department_id=>9, :follower_id=>41}, {:department_id=>4, :follower_id=>49}, {:department_id=>2, :follower_id=>58}, {:department_id=>5, :follower_id=>36}, {:department_id=>9, :follower_id=>63}, {:department_id=>2, :follower_id=>52}, {:department_id=>23, :follower_id=>26}, {:department_id=>5, :follower_id=>52}, {:department_id=>6, :follower_id=>30}] 

Relationship.create!(shoe_array.map{|arr| arr.merge!({user_id: 1})})