Question

如何使用联接查询Rails 5中的关联模型？我尝试过的是查看documentation和此question之后的public class Launcher extends Application { public static PSurfaceFX surface; @Override public void start(Stage primaryStage) throws Exception { Canvas canvas = (Canvas) surface.getNative(); // boilerplate GraphicsContext graphicsContext = canvas.getGraphicsContext2D(); // boilerplate surface.fx.context = graphicsContext; // boilerplate primaryStage.setTitle("FXML/Processing"); VBox root = FXMLLoader.load(new File("c:/Users/Mike/desktop/test.fxml").toURI().toURL()); SplitPane pane = (SplitPane) root.getChildren().get(1); // Manually get the item I want to add canvas to AnchorPane pane2 = (AnchorPane) pane.getItems().get(0); // Manually get the item I want to add canvas to pane2.getChildren().add(canvas); // Manually get the item I want to add canvas to canvas.widthProperty().bind(pane2.widthProperty()); canvas.heightProperty().bind(pane2.heightProperty()); Scene scene = new Scene(root, 800, 800); primaryStage.setScene(scene); primaryStage.show(); surface.stage = primaryStage; // boilerplate } }。我究竟做错了什么？我的查询没有返回任何结果。

DoctorLocation.joins(:location).where(:location => {:confidence => 2})

迁移

pry(main)> DoctorLocation.joins(:locations).where(:locations => {:confidence => 2})
=> #<DoctorLocation::ActiveRecord_Relation:0x3ff735a09d8c>

class DoctorLocation
   belongs_to :location

end

class Location
   has_many :doctor_locations, dependent: :destroy

end

Answer 1

您实际上有正确的查询。而是您的测试方法已损坏。

class DoctorLocation < ApplicationRecord
  belongs_to :location
  def self.with_confidence(c)
    DoctorLocation.joins(:location).where(locations: { confidence: c })
  end
end

此通过的规范确认它可以按预期工作：

require 'rails_helper'

RSpec.describe DoctorLocation, type: :model do

  after(:each) { DoctorLocation.destroy_all }
  it "includes locations with the correct confidence" do
    dl = DoctorLocation.create!(location: Location.create!(confidence: 2))
    DoctorLocation.create!(location: Location.create!(confidence: 1))
    expect(DoctorLocation.with_confidence(2)).to include dl
    expect(DoctorLocation.with_confidence(2).count).to eq 1
  end
  it "does not include rows without a match in the join table" do
    dl = DoctorLocation.create!(location: Location.create!(confidence: 1))
    expect(DoctorLocation.with_confidence(2)).to_not include dl
  end
end

Answer 2

在joins和where（散列参数）中，您需要声明关联名称（location），而不是表名称（locations）：

DoctorLocation.joins(:location).where(location: { confidence: 2 })

通常是造成混乱的原因。

Rails 5连接关联的过滤器

2 个答案: