我有一个看起来像这样的课程：
class ExtractDiffLineInfo
def initialize(*diffs)
@diffs = diffs
end
def all_line_num_starts
result = []
@diffs.each do |diff|
diff.body.lines.each do |diff_line|
if (m = diff_line.match(/\A@@\s+\-(\d+),(\d+)\s+\+(\d+),(\d+)\s+@@/))
a_start = m[1].to_i
result << a_start + 3
end
end
end
result
end
当我尝试传递ActiveRecord Collection个对象时，出现ActiveRecord Collection Proxy错误。
我正在尝试传递以下@diffs AR集合：
> @diffs
=> [#<Diff:0x007fc064000510
id: 13645,
body:
"@@ -1856,7 +1856,7 @@ def destroy_associations\n hm_options[k] = options[k] if options.key? k\n end\n \n- has_many name, scope, hm_options, &extension\n+ ActiveSupport::Deprecation.silence { has_many name, scope, hm_options, &extension }\n _reflections[name.to_s].parent_reflection = habtm_reflection\n end\n end",
commit_id: 1,
author: "Ryuta Kamizono",
author_gh_profile: "https://github.com/kamipo",
author_gh_avatar: "https://avatars.githubusercontent.com/u/12642?v=3",
commit_url: "https://github.com/rails/rails/commit/3cd4c7c0ffc3e00004a238304e903a140fcbcd67",
commit_msg:
"Suppress deprecation message to `has_and_belongs_to_many` only once\n\nPassing a class to `has_and_belongs_to_many` show deprecation message\nthree times. It is enough only once.",
gh_sha: "3cd4c7c0ffc3e00004a238304e903a140fcbcd67",
commit_date: Mon, 09 Jan 2017 20:00:53 UTC +00:00,
created_at: Fri, 10 Mar 2017 08:33:38 UTC +00:00,
updated_at: Fri, 10 Mar 2017 08:33:38 UTC +00:00,
position: nil,
num_additions: 2,
num_deletions: 2,
num_changes: 4,
starting_line_num: 1859>,
#<Diff:0x007fc063c2f648
id: 13644,
body:
"@@ -1827,7 +1827,7 @@ def has_and_belongs_to_many(name, scope = nil, **options, &extension)\n \n builder = Builder::HasAndBelongsToMany.new name, self, options\n \n- join_model = builder.through_model\n+ join_model = ActiveSupport::Deprecation.silence { builder.through_model }\n \n const_set join_model.name, join_model\n private_constant join_model.name\n",
commit_id: 1,
author: "Ryuta Kamizono",
author_gh_profile: "https://github.com/kamipo",
author_gh_avatar: "https://avatars.githubusercontent.com/u/12642?v=3",
commit_url: "https://github.com/rails/rails/commit/3cd4c7c0ffc3e00004a238304e903a140fcbcd67",
commit_msg:
"Suppress deprecation message to `has_and_belongs_to_many` only once\n\nPassing a class to `has_and_belongs_to_many` show deprecation message\nthree times. It is enough only once.",
gh_sha: "3cd4c7c0ffc3e00004a238304e903a140fcbcd67",
commit_date: Mon, 09 Jan 2017 20:00:53 UTC +00:00,
created_at: Fri, 10 Mar 2017 08:33:30 UTC +00:00,
updated_at: Fri, 10 Mar 2017 08:33:30 UTC +00:00,
position: nil,
num_additions: 2,
num_deletions: 2,
num_changes: 4,
starting_line_num: 1830>]
这样就过去了：
@diff_line_nums = ExtractDiffLineInfo.new(@diffs).all_line_num_starts
这是我得到的错误：
NoMethodError at /rails/associations-rb/3cd4c7c0ffc3e00004a238304e903a140fcbcd67
undefined method `body' for #<Diff::ActiveRecord_Associations_CollectionProxy:0x007fc0628280c8>
当我签出diff正在呼叫.body的对象时，我看到了这一点：
>> diff
=> #<ActiveRecord::Associations::CollectionProxy [#<Diff id: 13645, body: "@@ -1856,7 +1856,7 @@ def destroy_associations\n ...", commit_id: 1, author: "Ryuta Kamizono", author_gh_profile: "https://github.com/kamipo", author_gh_avatar: "https://avatars.githubusercontent.com/u/12642?v=3", commit_url: "https://github.com/rails/rails/commit/3cd4c7c0ffc3...", commit_msg: "Suppress deprecation message to `has_and_belongs_t...", gh_sha: "3cd4c7c0ffc3e00004a238304e903a140fcbcd67", commit_date: "2017-01-09 20:00:53", created_at: "2017-03-10 08:33:38", updated_at: "2017-03-10 08:33:38", position: nil, num_additions: 2, num_deletions: 2, num_changes: 4, starting_line_num: 1859>, #<Diff id: 13644, body: "@@ -1827,7 +1827,7 @@ def has_and_belongs_to_many(...", commit_id: 1, author: "Ryuta Kamizono", author_gh_profile: "https://github.com/kamipo", author_gh_avatar: "https://avatars.githubusercontent.com/u/12642?v=3", commit_url: "https://github.com/rails/rails/commit/3cd4c7c0ffc3...", commit_msg: "Suppress deprecation message to `has_and_belongs_t...", gh_sha: "3cd4c7c0ffc3e00004a238304e903a140fcbcd67", commit_date: "2017-01-09 20:00:53", created_at: "2017-03-10 08:33:30", updated_at: "2017-03-10 08:33:30", position: nil, num_additions: 2, num_deletions: 2, num_changes: 4, starting_line_num: 1830>]>
奇怪的是，如果我在运行时binding.pry进入initialize方法并检查传入的diffs参数，我会看到一个嵌套数组：
4: def initialize(*diffs)
=> 5: binding.pry
6: @diffs = diffs
7: end
[1] pry(#<ExtractDiffLineInfo>)> diffs
=> [[#<Diff:0x007fc065d635a8
id: 13645,
body:
"@@ -1856,7 +1856,7 @@ def destroy_associations\n hm_options[k] = options[k] if options.key? k\n end\n \n- has_many name, scope, hm_options, &extension\n+ ActiveSupport::Deprecation.silence { has_many name, scope, hm_options, &extension }\n _reflections[name.to_s].parent_reflection = habtm_reflection\n end\n end",
commit_id: 1,
author: "Ryuta Kamizono",
author_gh_profile: "https://github.com/kamipo",
author_gh_avatar: "https://avatars.githubusercontent.com/u/12642?v=3",
commit_url: "https://github.com/rails/rails/commit/3cd4c7c0ffc3e00004a238304e903a140fcbcd67",
commit_msg:
"Suppress deprecation message to `has_and_belongs_to_many` only once\n\nPassing a class to `has_and_belongs_to_many` show deprecation message\nthree times. It is enough only once.",
gh_sha: "3cd4c7c0ffc3e00004a238304e903a140fcbcd67",
commit_date: Mon, 09 Jan 2017 20:00:53 UTC +00:00,
created_at: Fri, 10 Mar 2017 08:33:38 UTC +00:00,
updated_at: Fri, 10 Mar 2017 08:33:38 UTC +00:00,
position: nil,
num_additions: 2,
num_deletions: 2,
num_changes: 4,
starting_line_num: 1859>,
#<Diff:0x007fc05bf57c88
id: 13644,
body:
"@@ -1827,7 +1827,7 @@ def has_and_belongs_to_many(name, scope = nil, **options, &extension)\n \n builder = Builder::HasAndBelongsToMany.new name, self, options\n \n- join_model = builder.through_model\n+ join_model = ActiveSupport::Deprecation.silence { builder.through_model }\n \n const_set join_model.name, join_model\n private_constant join_model.name\n",
commit_id: 1,
author: "Ryuta Kamizono",
author_gh_profile: "https://github.com/kamipo",
author_gh_avatar: "https://avatars.githubusercontent.com/u/12642?v=3",
commit_url: "https://github.com/rails/rails/commit/3cd4c7c0ffc3e00004a238304e903a140fcbcd67",
commit_msg:
"Suppress deprecation message to `has_and_belongs_to_many` only once\n\nPassing a class to `has_and_belongs_to_many` show deprecation message\nthree times. It is enough only once.",
gh_sha: "3cd4c7c0ffc3e00004a238304e903a140fcbcd67",
commit_date: Mon, 09 Jan 2017 20:00:53 UTC +00:00,
created_at: Fri, 10 Mar 2017 08:33:30 UTC +00:00,
updated_at: Fri, 10 Mar 2017 08:33:30 UTC +00:00,
position: nil,
num_additions: 2,
num_deletions: 2,
num_changes: 4,
starting_line_num: 1830>]]
可能导致此问题的原因以及如何解决？
答案 0 :(得分：2)
这是因为你的啪啪声
def initialize(*diffs) # <- this one
@diffs = diffs
end
你可以通过这样做来克服它，例如：
ExtractDiffLineInfo.new(*@diffs.to_a).all_line_num_starts
或者在初始化程序中展开数组
def initialize(*diffs)
@diffs = @diffs.flatten # _should_ work on activerelations, didn't test.
end
如果我是你，我会放弃splat并放弃传递单个diff的能力。
我需要能够轻松管理单个差异
您可以拥有专门的工厂方法。像这样：
class ExtractDiffLineInfo
def self.for_one_diff(diff)
new([diff])
end
def self.for_many_diffs(diffs)
new(diffs)
end
def initialize(*diffs)
@diffs = diffs
end
end
ExtractDiffLineInfo.for_one_diff(my_diff).all_line_num_starts
ExtractDiffLineInfo.for_many_diffs(@diffs).all_line_num_starts