如何基于搜索关键字栏从2个表中获取数据

Question

I have 2 tables schools and private_schools and they are not related to each other. What I need to do is to search the data from both tables to populate the results.

Both tables has the attribute name from which I need to get results. So when user will write some keyword the data will be searched from both tables.

Here is the query I am trying but it returns errors.

Query:

User.includes(:schools, :private_schools).where("schools.name = ? or 
private_schools.name = ?", params[:keyword])

I know the User. sort of thing is also useless and is also not needed but how we should cope this issue to search keywords from both tables at same time?

Error is:

ActiveRecord::PreparedStatementInvalid (wrong number of bind variables (1 for 2) in: schools.name = ? or private_schools.name = ?):

Per comments the code of models are:

Private School:

class PrivateSchool < ActiveRecord::Base
  belongs_to :teacher
  has_many :private_school_specializations, :dependent => :destroy
  has_many :private_classes
  has_many :invitation_promo_codes
  has_many :popular_schools, as: :resource, :dependent => :destroy
end

School:

class School < ActiveRecord::Base
  belongs_to :user
  has_many :students
  has_many :subjects
  has_many :teachers
  has_many :departments
  has_many :student_ids
  has_many :teacher_ids
  has_many :class_rooms
  has_many :popular_schools, as: :resource, :dependent => :destroy
end

User:

class User < ActiveRecord::Base
  has_one :school
  has_one :student
  has_one :teacher
  accepts_nested_attributes_for :student
  accepts_nested_attributes_for :teacher
end

Answer 1

ERROR REASON The following query is expecting two params, one to each ?

User.includes(:schools, :private_schools).where("schools.name = ? or 
private_schools.name = ?", params[:keyword])

So

User.includes(:schools, :private_schools).where("schools.name = ? or 
private_schools.name = ?", params[:keyword], params[:keyword])

Or just

User.includes(:schools, :private_schools).where("schools.name = :name or 
private_schools.name = :name", name: params[:keyword])

EXPECTING SOMETHING ELSE?

I know the User. sort of thing is also useless and is also not needed but how we should cope this issue to search keywords from both tables at same time?

Actually your User. query will return a list of users and not a list of schools or private_schools, so if you are not expecting a list of users you might be looking for something else... perhaps a list of schools?

If your schools and private_schools have the same structure you should take a look into inheritance and use the same table for both models. For now you could do something like:

def my_result
  schools = School.where(name: params[:name]).to_a
  private_schools = PrivateSchool.where(name: params[:name]).to_a
  schools + private_schools # combine both arrays
end

Answer 2

I have couple of things for you:

1. The includes is used to specify relationships to be included in the result set. So you don't have any relationship between schools and private_schools . So the straight forward you can't query it like this because you can't join two tables without having any relation. You can do a separate query for each table school and private_school .

    schools = School.where(name: params[:name]) schools << PrivateSchool.where(name: params[:name]) schools.flatten! 

You can put both into an array like this and then loop on the view. To just take out the names you can add:

   pluck(:name)

The includes is different thing. Like for example:

User.includes(:posts).where('posts.name = ?', 'example')

when the Post belong to the User so what will happen is the include will load the posts and when you try to fetch the posts with example name it would not fire any additional query as it has that data already loaded. So this only works when you have a relation between the models.

2. The school and private_school can be one single model if the attributes of both are same. You can just add an attribute of is_private which would be boolean and its value will be true in case of private schools. (This will depend on your attributes)

Answer 3

If you are going to do "complex" queries such as this frequently in your application, I highly recommend you check the "ransack" gem. It makes queries like this a breeze, and your codebase clean.

MyModel.search(:private_school_name_or_school_name_cont => params[:q).result

ref: https://github.com/activerecord-hackery/ransack