如何筛选Rails模型中太大的整数？

Question

我在PostGres 9.5中使用Rails 4.2.7。我在Rails迁移中有这个专栏..。

my_num               | integer                     | 

在我的模型中，我希望筛选太大的数字，并将它们设置为零。例如，数字“659722222222222”正在我的模型上设置，并导致以下错误

Error during processing: (RangeError) 659722222222222 is out of range for ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Integer with limit 4
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/type/integer.rb:45:in `ensure_in_range'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/type/integer.rb:23:in `type_cast_for_database'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/connection_adapters/abstract/quoting.rb:13:in `quote'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:641:in `block (2 levels) in values_sql_for_columns_and_attributes'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:631:in `each'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:631:in `each_with_index'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:631:in `each'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:631:in `map'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:631:in `block in values_sql_for_columns_and_attributes'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:630:in `map'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:630:in `values_sql_for_columns_and_attributes'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:530:in `import_without_validations_or_callbacks'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:490:in `import_with_validations'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:417:in `import_helper'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-import-0.16.1/lib/activerecord-import/import.rb:331:in `import'
/Users/davea/Documents/workspace//app/services/abstract_import_service.rb:161:in `block in save_my_object__time_results'

与其保存模型，我希望将字段设置为零，只当字段设置为对PostGres SQL太大的整数值时。我该怎么做？

注意，我不想更改PostGres列的teh列类型。你不认为这会那么容易，对吧？

Answer 1

2147483647是Postgres中类型整数的最大值。

before_save :is_too_big

def is_too_big
  if my_num > 2147483647
    # do something
  end
end

如果您不想在代码中添加一个神奇的数字，我建议您在超出范围的情况下捕捉到意外：

# somewhere in the code
u = User.new(my_num: 2147483648)
begin
 u.save
rescue RangeError => e
 u.my_num = nil
 u.save
end

Answer 2

添加前验证事件

before_validation :ensure_my_num_ok

如果它是坏的，只需设置值

def ensure_my_num_ok
  self.my_num = nil  if my_num > 100000000
end