Rails创建记录失败

Question

这是我的表结构

class CreateStudentAssignments < ActiveRecord::Migration[5.1]
  def change
    create_table :student_assignments do |t|
      t.string :title
      t.string :subject
      t.text :description
      t.float :amount, default: 0
      t.date :start_date
      t.date :due_date
      t.integer :word_count
      t.time :approximate_estimated_duration
      t.boolean :active, default: true
      t.float :overall_rating
      t.integer :view_count, default: 0
      t.boolean :assignment_approved, default: false
      t.references :assignment_status, foreign_key: true
      t.references :student, foreign_key: { to_table: :users }
      t.references :difficulty_level, foreign_key: true
      t.references :writer, foreign_key: { to_table: :users } # Assignment accepted writer

      t.timestamps
    end
  end
end

尝试创建记录时

p = {title: "title", subject: "subject", description: "des", amount: 5.00, start_date: Date.today + 1, due_date: Date.today + 5, word_count: 100, approximate_estimated_duration: 1000, overall_rating: 4, view_count:4, assignment_status: AssignmentStatus.last, difficulty_level_id: 4, student: User.last}


StudentAssignment.create(p).errors
ActiveModel::MissingAttributeError: can't write unknown attribute `student_id`
    from (irb):56

如何传递该用户？

提前致谢