我在Rails中编写RESTful API,当我创建Label对象并使用.save()
方法时,标签已正确保存到数据库中,但调用@label.id
将返回null。
puts
语句验证除id字段外的所有内容都是正确的。我还验证了数据库有正确的ID。
另外值得注意的是:这是在嵌套资源网址中:POST /members/:member_id/labels/
。
以前有没有人经历过这个?
def create
if params[:member_id] and params[:title]
# Periods in a username will have been translated to underscores
member_id = params[:member_id].gsub('_', '.')
title = params[:title]
# @member = Member.find(member_id) # No longer in use
@label = Label.new(:username => member_id, :title => title)
if @label.save
puts " *** label: #{@label.inspect}"
@label.reload
respond_to do |format|
format.json { render :json => @label, :status => :created and return }
end
else
respond_with :status => 406, :errors => @label.errors and return
end
end
respond_with :status => 406, :errors => [ :message => "member_id and title parameters must be provided" ] and return
end
不幸的是,由于我连接到最初通过PHP查看的现有PostgreSQL数据库,因此我无法提供所需的迁移文件。但是,下面是create table
语句以及select *
的外观。
DROP TABLE student_labels;
CREATE TABLE student_labels (
id serial not null,
username text not null,
title text not null,
created_at timestamp not null default now(),
updated_at timestamp not null default now(),
deleted_at timestamp
);
development=> select * from student_labels; id | username | title | created_at | updated_at | deleted_at ----+----------+--------------+----------------------------+----------------------------+------------ 7 | F0003 | Boom | 2011-03-10 05:49:06.01771 | 2011-03-10 05:49:06.01771 | 8 | F0003 | Boom | 2011-03-10 05:49:28.659 | 2011-03-10 05:49:28.659 | 9 | F0003 | Boom | 2011-03-10 05:52:03.343815 | 2011-03-10 05:52:03.343815 | 10 | F0003 | Boom | 2011-03-10 05:53:07.803489 | 2011-03-10 05:53:07.803489 |
答案 0 :(得分:3)
问题是您的id
列不是主键,因此当数据库要求输入最后一行的id
时,数据库不知道要提供哪些内容。