Gem rescue 为什么不处理 SQLite3::SQLException 异常
require "sqlite3"
require "sequel"
DB = Sequel.sqlite # memroy
if true
DB.create_table :posts do
primary_key :id
String :email, null: false
end
end
Post = DB[:posts]
begin
row = Post.insert(mail: "[email protected]")
rescue SQLite3::SQLException => e
puts e
end
执行会输出异常栈，SQLite3::SQLException: table posts has no column named mail 但不执行 rescue 代码块
rescue StandardError => e
puts e.class # Sequel::DatabaseError
end
e.inspect # #<Sequel::DatabaseError: SQLite3::SQLException: table posts has no column named mail>
Reply to
xinyifly
xinyifly
为什么命令行运行报 SQLite3::SQLException 在代码里捕获是 Sequel::DatabaseError
看代码
- Sequel::DatabaseError < Sequel::Error < ::StandardError
- SQLite3::SQLException < SQLite3::Exception < ::StandardError
这两个有什么不同吗？为什么一个行，另一个不行
看样子是 Sequel 捕获了 SQLite3 的异常，包裹在 Sequel::DatabaseError 里面再抛出，到用户代码这里能捕获的是 Sequel::DatabaseError。
Reply to
tablecell
tablecell
这段代码抛的异常是 Sequel::DatabaseError ， SQLite3::SQLException 不是 Sequel::DatabaseError 的父类，自然捕获不到。
Reply to
xinyifly
xinyifly
直接运行 Post.insert(mail: "[email protected]") 为什么不报 Sequel::DatabaseError 而是 SQLite3::SQLException
Reply to
tablecell
tablecell
你应该把异常的 message 和类搞混了，终端看到的 SQLite3::SQLException 是 message 的一部分。
可以把完整错误栈信息贴上来看看。
Reply to
Rei
Rei
$ ruby test.rb
Traceback (most recent call last):
13: from test.rb:14:in `<main>'
12: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sequel-5.48.0/lib/sequel/dataset/actions.rb:401:in `insert'
11: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sequel-5.48.0/lib/sequel/dataset/actions.rb:1109:in `execute_insert'
10: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sequel-5.48.0/lib/sequel/adapters/sqlite.rb:159:in `execute_insert'
9: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sequel-5.48.0/lib/sequel/adapters/sqlite.rb:193:in `_execute'
8: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sequel-5.48.0/lib/sequel/database/connecting.rb:269:in `synchronize'
7: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sequel-5.48.0/lib/sequel/connection_pool/threaded.rb:92:in `hold'
6: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sequel-5.48.0/lib/sequel/adapters/sqlite.rb:202:in `block in _execute'
5: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sequel-5.48.0/lib/sequel/database/logging.rb:38:in `log_connection_yield'
4: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sequel-5.48.0/lib/sequel/adapters/sqlite.rb:202:in `block (2 levels) in _execute'
3: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sqlite3-1.4.2.mspgreg-x64-mingw32/lib/sqlite3/database.rb:194:in `execute'
2: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sqlite3-1.4.2.mspgreg-x64-mingw32/lib/sqlite3/database.rb:148:in `prepare'
1: from Ruby25-x64/lib/ruby/gems/2.5.0/gems/sqlite3-1.4.2.mspgreg-x64-mingw32/lib/sqlite3/database.rb:148:in `new'
Ruby25-x64/lib/ruby/gems/2.5.0/gems/sqlite3-1.4.2.mspgreg-x64-mingw32/lib/sqlite3/database.rb:148:in `initialize': SQLite3::SQLException: table posts has no column named mail (Sequel::DatabaseError)