导轨连接两个表

Question

Models:

Fruit:  fields - "fruit_type"  

has_many: apples
has_many :bananas  



Apple fields: f1, f2, fruit_id, some other fields  
belongs_to: fruit

Banana: f1, f2, fruit_id, some other fields related to banana  
belongs_to :fruit

How to get all fruits by searching fruit_type, f1, f2 fields. We have 3 inputs: fruit_type, f1, f2 so if we type in only one field(say f1), only f1 field wil be searched. If fruit_type, f1, f2 inputs are entered, both fields f1, f2 will be searched and finally fruits will be returned.

Lets say either f1 or only f2 input is entered, then below works:

scope = Fruit.joins("left join apples on apples.fruit_id=fruits.id left join bananas on bananas.id=fruits.id where (apples.f1 like '#{f1_input_val}%' or bananas.f1 like '#{f1_input_val}%')")  

If fruit_type, f1, f2 input also entered, whats the query ? Below not working:

scope = Fruit.all #if no queries

scope = scope.where("fruit_type like ?", "#{fruit_type_input}%")  if fruit_type_input.present?  

scope = scope.joins("left join apples on apples.fruit_id=fruits.id left join bananas on bananas.id=fruits.id where (apples.f1 like '#{f1_input_val}%' or bananas.f1 like '#{f1_input_val}%')") if f1_input_val.present?  

scope = scope.joins("left join apples on apples.fruit_id=fruits.id left join bananas on bananas.id=fruits.id where (apples.f2 like '#{f2_input_val}%' or bananas.f2 like '#{f2_input_val}%')") if f2_input_val.present?

Answer 1

I think you need to separate joinining and where clauses.

scope = Fruit.all #if no queries

scope = scope.where("fruit_type like ?", "#{fruit_type_input}%")  if fruit_type_input.present?  

if f1_input_val.present? or f2_input_val.present?
  scope = scope.joins("left join apples on apples.fruit_id=fruits.id left join bananas on bananas.id=fruits.id")

  scope = scope.where("apples.f1 like '#{f1_input_val}%' or bananas.f1 like '#{f1_input_val}%')") if f1_input_val.present?  
  scope = scope.where("apples.f2 like '#{f2_input_val}%' or bananas.f2 like '#{f2_input_val}%')") if f2_input_val.present?
end
scope # just return a resulted scope