问外键违规发现在您的夹具数据。确保您所指的不是关联中不存在的标签

EN

ERROR:  insert or update on table "friendships" violates foreign key constraint "fk_rails_e3733b59b7"
DETAIL:  Key (user_id)=(999) is not present in table "users".

RAILS_ENV=test bin/rails db:reset
RAILS_ENV=test bin/rails db:fixtures:load
RAILS_ENV=test bin/rails c 

ActiveRecord::Base.connection.execute(<<~SQL)
  do $$
    declare r record;
  BEGIN
  FOR r IN (
    SELECT FORMAT(
      'UPDATE pg_constraint SET convalidated=false WHERE conname = ''%I''; ALTER TABLE %I VALIDATE CONSTRAINT %I;',
      constraint_name,
      table_name,
      constraint_name
    ) AS constraint_check
    FROM information_schema.table_constraints WHERE constraint_type = 'FOREIGN KEY'
  )
    LOOP
      EXECUTE (r.constraint_check);
    END LOOP;
  END;
  $$;
SQL


# =>
# PG::ForeignKeyViolation: ERROR:  insert or update on table "friendships" violates foreign key constraint "fk_rails_e3733b59b7" (ActiveRecord::InvalidForeignKey)
# DETAIL:  Key (user_id)=(999) is not present in table "users".

ActiveRecord::Base.connection.execute("PRAGMA foreign_key_check")

# => [{"table"=>"friendships", "rowid"=>1, "parent"=>"users", "fkid"=>0}]

# Posts fixture
one:
  title: MyString
  content: MyText

# Comment fixture
one: 
  comment_content: MyString
  post: one

# Posts fixture
one:
  title: MyString
  content: MyText

# Comment fixture
one: 
  comment_content: MyString
  post: somethingrandom

rails new testapp
cd testapp
rails g scaffold posts title content:text 
rails g scaffold comment comment_content:text post:belongs_to
# Add this to post.rb: has_many :comments, dependent: :destroy
rake db:migrate

one:
  title: MyString
  content: MyText

two:
  title: MyString
  content: MyText

one:
  comment_content: MyText
  post: one

two:
  comment_content: MyText
  post: two

one:
  title: MyString
  content: MyText

two:
  title: MyString
  content: MyText

one:
  comment_content: MyText
  post: one

two:
  comment_content: MyText
  post: twwo # <-- typo!

RuntimeError: Foreign key violations found in your fixture data. 
Ensure you aren't referring to labels that don't exist on associations.

Error:
PostsControllerTest#test_should_create_post:
ActiveRecord::NotNullViolation: PG::NotNullViolation: 
ERROR:  null value in column "post_id" violates not-null constraint