您好我一直在尝试将一个rails应用程序部署到Heroku，这是一个使用Devise的学生 - 教师交流平台。该应用程序在本地运行正常，但我无法运行迁移，所以虽然主页等在heroku上工作正常，但当我点击注册它不起作用（PG :: UndefinedTable：ERROR ....）
我对迁移文件做了一些更改，试图更接近解决问题，现在它不允许我运行rake db：本地迁移。
学生和教师是设计用户的类型。英语成绩和数学成绩属于一名教师和一名学生，教师/学生可以拥有许多这些成绩。任务和生成的反馈属于教师。
rake db:migrate produces the following errors.
== 20160714153750 CreateGeneratedFeedbacks: migrating =========================
-- create_table(:generated_feedbacks)
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:
PG::UndefinedTable: ERROR: relation "teachers" does not exist
: CREATE TABLE "generated_feedbacks" ("id" serial primary key, "performance_grade" character varying, "teacher_id" integer, "subject" character varying, "auto_feedback" text, "subcategory" character varying, "created_at" timestamp NOT NULL, "updated_at" timestamp NOT NULL, CONSTRAINT "fk_rails_ee351f38a1"
FOREIGN KEY ("teacher_id")
REFERENCES "teachers" ("id")
)
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:98:in `async_exec'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:98:in `block in execute'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:566:in `block in log'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activesupport-5.0.0/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:560:in `log'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:97:in `execute'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/schema_statements.rb:283:in `create_table'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:845:in `block in method_missing'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:814:in `block in say_with_time'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:814:in `say_with_time'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:834:in `method_missing'
/Users/Jack/programming/ruby/second_attempt/second_attempt/db/migrate/20160714153750_create_generated_feedbacks.rb:4:in `change'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:788:in `exec_migration'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:772:in `block (2 levels) in migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:771:in `block in migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:398:in `with_connection'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:770:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:950:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1211:in `block in execute_migration_in_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1279:in `block in ddl_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `block in transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/transaction.rb:189:in `within_new_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/transactions.rb:211:in `transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1279:in `ddl_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1210:in `execute_migration_in_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1183:in `block in migrate_without_lock'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1182:in `each'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1182:in `migrate_without_lock'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1131:in `block in migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1298:in `with_advisory_lock'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1131:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1005:in `up'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:983:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/tasks/database_tasks.rb:161:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/railties/databases.rake:58:in `block (2 levels) in <top (required)>'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/rake-11.2.2/exe/rake:27:in `<top (required)>'
/Users/Jack/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval'
/Users/Jack/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>'
ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR: relation "teachers" does not exist
: CREATE TABLE "generated_feedbacks" ("id" serial primary key, "performance_grade" character varying, "teacher_id" integer, "subject" character varying, "auto_feedback" text, "subcategory" character varying, "created_at" timestamp NOT NULL, "updated_at" timestamp NOT NULL, CONSTRAINT "fk_rails_ee351f38a1"
FOREIGN KEY ("teacher_id")
REFERENCES "teachers" ("id")
)
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:98:in `async_exec'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:98:in `block in execute'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:566:in `block in log'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activesupport-5.0.0/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:560:in `log'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:97:in `execute'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/schema_statements.rb:283:in `create_table'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:845:in `block in method_missing'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:814:in `block in say_with_time'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:814:in `say_with_time'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:834:in `method_missing'
/Users/Jack/programming/ruby/second_attempt/second_attempt/db/migrate/20160714153750_create_generated_feedbacks.rb:4:in `change'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:788:in `exec_migration'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:772:in `block (2 levels) in migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:771:in `block in migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:398:in `with_connection'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:770:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:950:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1211:in `block in execute_migration_in_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1279:in `block in ddl_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `block in transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/transaction.rb:189:in `within_new_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/transactions.rb:211:in `transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1279:in `ddl_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1210:in `execute_migration_in_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1183:in `block in migrate_without_lock'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1182:in `each'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1182:in `migrate_without_lock'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1131:in `block in migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1298:in `with_advisory_lock'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1131:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1005:in `up'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:983:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/tasks/database_tasks.rb:161:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/railties/databases.rake:58:in `block (2 levels) in <top (required)>'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/rake-11.2.2/exe/rake:27:in `<top (required)>'
/Users/Jack/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval'
/Users/Jack/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>'
PG::UndefinedTable: ERROR: relation "teachers" does not exist
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:98:in `async_exec'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:98:in `block in execute'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:566:in `block in log'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activesupport-5.0.0/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:560:in `log'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:97:in `execute'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/schema_statements.rb:283:in `create_table'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:845:in `block in method_missing'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:814:in `block in say_with_time'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:814:in `say_with_time'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:834:in `method_missing'
/Users/Jack/programming/ruby/second_attempt/second_attempt/db/migrate/20160714153750_create_generated_feedbacks.rb:4:in `change'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:788:in `exec_migration'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:772:in `block (2 levels) in migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:771:in `block in migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:398:in `with_connection'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:770:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:950:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1211:in `block in execute_migration_in_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1279:in `block in ddl_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `block in transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/transaction.rb:189:in `within_new_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:232:in `transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/transactions.rb:211:in `transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1279:in `ddl_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1210:in `execute_migration_in_transaction'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1183:in `block in migrate_without_lock'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1182:in `each'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1182:in `migrate_without_lock'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1131:in `block in migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1298:in `with_advisory_lock'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1131:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:1005:in `up'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/migration.rb:983:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/tasks/database_tasks.rb:161:in `migrate'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/activerecord-5.0.0/lib/active_record/railties/databases.rake:58:in `block (2 levels) in <top (required)>'
/Users/Jack/.rvm/gems/ruby-2.3.0/gems/rake-11.2.2/exe/rake:27:in `<top (required)>'
/Users/Jack/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval'
/Users/Jack/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>'
Tasks: TOP => db:migrate
设计用户迁移
class DeviseCreateUsers < ActiveRecord::Migration[5.0]
def change
create_table :users do |t|
## Database authenticatable
t.string :email, null: false, default: ""
t.string :encrypted_password, null: false, default: ""
#adding
t.string :type
t.string :teacher_name
t.string :teacher_email
## Recoverable
t.string :reset_password_token
t.datetime :reset_password_sent_at
## Rememberable
t.datetime :remember_created_at
## Trackable
t.integer :sign_in_count, default: 0, null: false
t.datetime :current_sign_in_at
t.datetime :last_sign_in_at
t.string :current_sign_in_ip
t.string :last_sign_in_ip
#additional values
t.string :first_name
t.string :last_name
## Confirmable
# t.string :confirmation_token
# t.datetime :confirmed_at
# t.datetime :confirmation_sent_at
# t.string :unconfirmed_email # Only if using reconfirmable
## Lockable
# t.integer :failed_attempts, default: 0, null: false # Only if lock strategy is :failed_attempts
# t.string :unlock_token # Only if unlock strategy is :email or :both
# t.datetime :locked_at
t.timestamps null: false
end
add_index :users, :email, unique: true
add_index :users, :reset_password_token, unique: true
# add_index :users, :confirmation_token, unique: true
# add_index :users, :unlock_token, unique: true
end
end
英语成绩（或多或少与数学相同）
class CreateEnglishGrades < ActiveRecord::Migration[5.0]
def change
create_table :english_grades do |t|
t.references :teacher, foreign_key: true
t.references :student, foreign_key: true
t.string :title
t.string :subcategory
t.string :performance_grade
t.string :feedback
t.date :grade_date
t.timestamps
end
end
end
生成的反馈： class CreateGeneratedFeedbacks＆lt; ActiveRecord的::迁移[5.0] 改变
create_table :generated_feedbacks do |t|
t.string :performance_grade
t.references :teacher, foreign_key: true
t.string :subject
t.text :auto_feedback
t.string :subcategory
t.timestamps
end
end
end
任务：
class CreateTasks < ActiveRecord::Migration[5.0]
def change
create_table :tasks do |t|
t.string :subject
t.text :task
t.references :teacher, foreign_key: true
t.date :due_date
t.text :description
t.timestamps
end
end
end
模型
英语成绩（与数学成绩相同）
class EnglishGrade < ApplicationRecord
belongs_to :teacher
belongs_to :student
end
生成的反馈
class GeneratedFeedback < ApplicationRecord
belongs_to :teacher
end
用户
class User < ApplicationRecord
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
end
学生
class Student < User
has_many :grades
has_many :maths_grades
has_many :english_grades
has_many :generated_feedback
end
教师
class Teacher < User
has_many :grades
has_many :maths_grades
has_many :english_grades
has_many :generated_feedback
has_many :task
end
架构：
ActiveRecord::Schema.define(version: 20160713100728) do
# These are extensions that must be enabled in order to support this database
enable_extension "plpgsql"
create_table "english_grades", force: :cascade do |t|
t.integer "teacher_id"
t.integer "student_id"
t.string "title"
t.string "subcategory"
t.string "performance_grade"
t.string "feedback"
t.date "grade_date"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.index ["student_id"], name: "index_english_grades_on_student_id", using: :btree
t.index ["teacher_id"], name: "index_english_grades_on_teacher_id", using: :btree
end
create_table "grades", force: :cascade do |t|
t.integer "student_id"
t.integer "teacher_id"
t.text "feedback"
t.integer "percentage_score"
t.string "grade_type"
t.string "grade_letter"
t.date "grade_date"
t.string "subject"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.index ["student_id"], name: "index_grades_on_student_id", using: :btree
t.index ["teacher_id"], name: "index_grades_on_teacher_id", using: :btree
end
create_table "maths_grades", force: :cascade do |t|
t.integer "teacher_id"
t.integer "student_id"
t.string "title"
t.string "subcategory"
t.string "performance_grade"
t.string "feedback"
t.date "grade_date"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.index ["student_id"], name: "index_maths_grades_on_student_id", using: :btree
t.index ["teacher_id"], name: "index_maths_grades_on_teacher_id", using: :btree
end
create_table "users", force: :cascade do |t|
t.string "email", default: "", null: false
t.string "encrypted_password", default: "", null: false
t.string "reset_password_token"
t.datetime "reset_password_sent_at"
t.datetime "remember_created_at"
t.integer "sign_in_count", default: 0, null: false
t.datetime "current_sign_in_at"
t.datetime "last_sign_in_at"
t.string "current_sign_in_ip"
t.string "last_sign_in_ip"
t.string "first_name"
t.string "last_name"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "type"
t.string "Teacher_name"
t.string "teacher_email"
t.index ["email"], name: "index_users_on_email", unique: true, using: :btree
t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true, using: :btree
end
end
非常感谢，我已经坚持了这个问题将近一个星期，所以任何帮助都将非常感激。
可能相关或不相关的额外信息：
- 我认为这可能是我的迁移文件的问题，因为我之前有一些添加了额外的列。为了尝试解决这个问题，我最近删除了这些额外的迁移文件，并更新了现有迁移文件中所需的列。
答案 0 :(得分：1)
您正在为User，Student和Teacher模型使用单表继承。虽然模型本身看起来很好，但迁移缺乏正确处理关联的信息。
当你这样做时
t.references :teacher, foreign_key: true
Rails尝试创建一个外键，引用不存在的teachers表。
…CONSTRAINT "fk_rails_ee351f38a1"
FOREIGN KEY ("teacher_id") REFERENCES "teachers" ("id")…
您应该定义这样的引用：
create_table :generated_feedbacks do |t|
t.references :teacher, references: :users
…
end
CreateEnglishGrades应使用类似的方法：
create_table :english_grades do |t|
t.references :teacher, references: :users
t.references :student, references: :users
…
end
然后需要单独定义外键：
add_foreign_key :english_grades, :users, column: :teacher_id
add_foreign_key :english_grades, :users, column: :student_id