2008 年 4 月
簡介
Ruby 是一種動態指令碼語言，由於熱門的 Rails 網頁開發架構，近年來受到許多關注。本文將說明如何使用 Ruby 與 Google Data API 服務互動。我們不會著重於 Rails，而是更想說明動態饋給的基礎 HTTP 指令和結構。您可以使用 Ruby 的互動式殼層 irb，從指令列執行本文中的所有範例。
如您在 cURL 文章中瞭解到的，Google Data API 使用 Atom 發布通訊協定 來表示、建立及更新網路資源。這項通訊協定的優點在於，可使用標準 HTTP 動詞來制定要求，並以標準 HTTP 狀態碼回應。
本文使用的動詞包括 GET (擷取內容)、POST (上傳新內容) 和 PUT (更新現有內容)。使用 Google Data API 時，您可能會遇到一些標準代碼，例如 200 代表成功擷取動態饋給或項目，201 則代表成功建立或更新資源。如果發生錯誤 (例如傳送格式錯誤的要求)，系統會傳回 400 代碼 (表示「要求格式錯誤」)。回應主體會提供更詳細的訊息，說明確切的錯誤原因。
Ruby 在「Net」模組中提供實用的偵錯選項。為確保這些程式碼範例不會過長，我在此並未啟用這項功能。
取得並安裝 Ruby
如果您使用 Linux，可以透過大多數的套件管理系統安裝 Ruby。如要瞭解其他作業系統的相關資訊及取得完整原始碼，請前往 http://www.ruby-lang.org/en/downloads/。Irb 是我們將用於這些範例的互動式殼層，預設應會安裝。如要使用這裡列出的程式碼範例，您也需要安裝 XmlSimple，這個小型程式庫可將 XML 剖析為 Ruby 資料結構。如要取得/安裝 XmlSimple，請前往 http://xml-simple.rubyforge.org/
在電腦上執行 Ruby 副本後，您可以使用 Net:HTTP 套件向 Google 的資料服務提出基本要求。下列程式碼片段說明如何從 Ruby 的互動式殼層匯入必要項目。我們要做的是要求「net/http」套件、剖析 YouTube 評分最高的影片動態消息網址，然後執行 HTTP GET 要求。
irb(main):001:0> require 'net/http' => true irb(main):002:0> youtube_top_rated_videos_feed_uri = \ 'http://gdata.youtube.com/feeds/api/standardfeeds/top_rated' => "http://gdata.youtube.com/feeds/api/standardfeeds/top_rated" irb(main):003:0> uri = \ URI.parse(youtube_top_rated_videos_feed_uri) => #<URI::HTTP:0xfbf826e4 URL:http://gdata.youtube.com/feeds/api/standardfeeds/top_rated> irb(main):004:0> uri.host => "gdata.youtube.com" irb(main):005:0> Net::HTTP.start(uri.host, uri.port) do |http| irb(main):006:1* puts http.get(uri.path) irb(main):007:1> end #<Net::HTTPOK:0xf7ef22cc>
該要求應該會將相當多的 XML 回應到指令列。你可能已注意到，所有項目都包含在 <feed> 元素中，並稱為 <entry> 元素。我們暫時不必擔心 XML 格式，我只是想說明如何使用 HTTP 提出基本的 Google Data API 要求。我們現在要切換 API，並專注於試算表，因為可傳送及擷取的資訊更適合透過指令列操作。
驗證 | 使用 Google 試算表 API
我們將再次從擷取項目元素動態饋給開始。不過，這次我們要使用自己的試算表。為此，我們必須先透過 Google 帳戶服務進行驗證。
如您在這份文件中瞭解到的，有兩種方式可向 Google 服務進行驗證。AuthSub 適用於網頁型應用程式，簡單來說，就是代碼交換程序。AuthSub 的真正優點在於，應用程式不必儲存使用者憑證。ClientLogin 適用於「已安裝」的應用程式。在 ClientLogin 程序中，使用者名稱和密碼會透過 https 連同識別您要使用服務的字串，一併傳送至 Google 服務。Google 試算表 API 服務的識別字串為 wise。
切換回互動式殼層，然後使用 Google 進行驗證。請注意，我們使用 https 傳送驗證要求和憑證：
irb(main):008:0> require 'net/https'
=> true
irb(main):009:0> http = Net::HTTP.new('www.google.com', 443)
=> #<Net::HTTP www.google.com:443 open=false>
irb(main):010:0> http.use_ssl = true
=> true
irb(main):011:0> path = '/accounts/ClientLogin'
=> "/accounts/ClientLogin"
# Now we are passing in our actual authentication data.
# Please visit OAuth For Installed Apps for more information
# about the accountType parameter
irb(main):014:0> data = \
irb(main):015:0* 'accountType=HOSTED_OR_GOOGLE&Email=your email' \
irb(main):016:0* '&Passwd=your password' \
irb(main):017:0* '&service=wise'
=> accountType=HOSTED_OR_GOOGLE&Email=your email&Passwd=your password&service=wise"
# Set up a hash for the headers
irb(main):018:0> headers = \
irb(main):019:0* { 'Content-Type' => 'application/x-www-form-urlencoded'}
=> {"Content-Type"=>"application/x-www-form-urlencoded"}
# Post the request and print out the response to retrieve our authentication token
irb(main):020:0> resp, data = http.post(path, data, headers)
warning: peer certificate won't be verified in this SSL session
=> [#<Net::HTTPOK 200 OK readbody=true>, "SID=DQAAAIIAAADgV7j4F-QVQjnxdDRjpslHKC3M ... [ snipping out the rest of the authentication strings ]
# Strip out our actual token (Auth) and store it
irb(main):021:0> cl_string = data[/Auth=(.*)/, 1]
=> "DQAAAIUAAADzL... [ snip ]
# Build our headers hash and add the authorization token
irb(main):022:0> headers["Authorization"] = "GoogleLogin auth=#{cl_string}"
=> "GoogleLogin auth=DQAAAIUAAADzL... [ snip ]
好的。現在我們已完成驗證，請嘗試使用以下要求擷取自己的試算表：
http://spreadsheets.google.com/feeds/spreadsheets/private/full
由於這是經過驗證的要求，我們也想傳遞標頭。事實上，由於我們會對各種動態消息提出多項要求，因此不妨將這項功能包裝成簡單的函式，並呼叫 get_feed。
# Store the URI to the feed since we may want to use it again
irb(main):023:0> spreadsheets_uri = \
irb(main):024:0* 'http://spreadsheets.google.com/feeds/spreadsheets/private/full'
# Create a simple method to obtain a feed
irb(main):025:0> def get_feed(uri, headers=nil)
irb(main):026:1> uri = URI.parse(uri)
irb(main):027:1> Net::HTTP.start(uri.host, uri.port) do |http|
irb(main):028:2* return http.get(uri.path, headers)
irb(main):029:2> end
irb(main):030:1> end
=> nil
# Lets make a request and store the response in 'my_spreadsheets'
irb(main):031:0> my_spreadsheets = get_feed(spreadsheets_uri, headers)
=> #<Net::HTTPOK 200 OK readbody=true>
irb(main):032:0> my_spreadsheets
=> #<Net::HTTPOK 200 OK readbody=true>
# Examine our XML (showing only an excerpt here...)
irb(main):033:0> my_spreadsheets.body
=> "<?xml version='1.0' encoding='UTF-8'?><feed xmlns='http://www.w3.org/2005/Atom' xmlns:openSearch='http://a9.com/-/spec/opensearchrss/1.0/'>
<id>http://spreadsheets.google.com/feeds/spreadsheets/private/full</id><updated>2008-03-20T20:49:39.211Z</updated>
<category scheme='http://schemas.google.com/spreadsheets/2006' term='http://schemas.google.com/spreadsheets/2006#spreadsheet'/>
<title type='text'>Available Spreadsheets - test.api.jhartmann@gmail.com</title><link rel='alternate' type='text/html' href='http://docs.google.com'/>
<link rel='http://schemas.google.com/g/2005#feed' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/spreadsheets/private/full'/><link rel='self' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/spreadsheets/private/full?tfe='/>
<openSearch:totalResults>6</openSearch:totalResults><openSearch:startIndex>1</openSearch:startIndex><entry>
<id>http://spreadsheets.google.com/feeds/spreadsheets/private/full/o04927555739056712307.4365563854844943790</id><updated>2008-03-19T20:44:41.055Z</updated><category scheme='http://schemas.google.com/spreadsheets/2006' term='http://schemas.google.com/spreadsheets/2006#spreadsheet'/><title type='text'>test02</title><content type='text'>test02</content><link rel='http://schemas.google.com/spreadsheets/2006#worksheetsfeed' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/worksheets/o04927555739056712307.4365563854844943790/private/full'/><link rel='alternate' type='text/html' href='http://spreadsheets.google.com/ccc?key=o04927555739056712307.4365563854844943790'/><link rel='self' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/spreadsheets/private/full/o04927555739056712307.4365563854844943790'/><author><name>test.api.jhartmann</name><email>test.api.jhartmann@gmail.com</email></author></entry><entry> ...
我們再次看到許多 XML，由於您不必擔心從指令列解讀 XML，因此我已在上方降低其重要性。為了方便使用者操作，請改用 XmlSimple 將其剖析為資料結構：
# Perform imports
irb(main):034:0> require 'rubygems'
=> true
irb(main):035:0> require 'xmlsimple'
=> true
irb(main):036:0> doc = \
irb(main):037:0* XmlSimple.xml_in(my_spreadsheets.body, 'KeyAttr' => 'name')
# Import the 'pp' module for 'pretty printing'
irb(main):038:0> require 'pp'
=> true
# 'Pretty-print' our XML document
irb(main):039:0> pp doc
{"totalResults"=>["6"],
"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#spreadsheet",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"title"=>
[{"type"=>"text",
"content"=>"Available Spreadsheets - Test-account"}],
"startIndex"=>["1"],
"id"=>["http://spreadsheets.google.com/feeds/spreadsheets/private/full"],
"entry"=>
[{"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#spreadsheet",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"title"=>[{"type"=>"text", "content"=>"blank"}],
"author"=>
[{"name"=>["Test-account"],
"email"=>["my email"]}],
"id"=>
["http://spreadsheets.google.com/feeds/spreadsheets/private/full/o04927555739056712307.3387874275736238738"],
"content"=>{"type"=>"text", "content"=>"blank"},
"link"=>
[ snipping out the rest of the XML ]
取得工作表
因此如上方的輸出內容所示，我的動態饋給包含 6 個試算表。為簡化本文，我已刪除上述 XML 輸出內容的其餘部分 (以及大部分其他清單)。如要深入瞭解這份試算表，我們需要執行幾個步驟：
- 取得試算表索引
- 使用試算表金鑰取得工作表動態饋給
- 取得要使用的工作表 ID
- 要求 cellsFeed 或 listFeed，存取工作表的實際內容
這聽起來可能需要花費許多心力，但只要編寫幾個簡單的方法，您就會發現一切都很容易。cellsFeed 和 listFeed 是工作表實際儲存格內容的兩種不同表示法。listFeed 代表一整列資訊，建議用於 POST 新資料。cellFeed 代表個別儲存格，可用於更新個別儲存格，或批次更新多個儲存格 (兩者都使用 PUT)。詳情請參閱 Google Sheets API 說明文件。
首先，我們需要擷取試算表金鑰 (如上方的 XML 輸出內容所示)，然後取得工作表動態消息：
# Extract the spreadsheet key from our datastructure
irb(main):040:0> spreadsheet_key = \
irb(main):041:0* doc["entry"][0]["id"][0][/full\/(.*)/, 1]
=> "o04927555739056712307.3387874275736238738"
# Using our get_feed method, let's obtain the worksheet feed
irb(main):042:0> worksheet_feed_uri = \
irb(main):043:0* "http://spreadsheets.google.com/feeds/worksheets/#{spreadsheet_key}/private/full"
=> "http://spreadsheets.google.com/feeds/worksheets/o04927555739056712307.3387874275736238738/private/full"
irb(main):044:0> worksheet_response = get_feed(worksheet_feed_uri, headers)
=> #<Net::HTTPOK 200 OK readbody=true>
# Parse the XML into a datastructure
irb(main):045:0> worksheet_data = \
irb(main):046:0* XmlSimple.xml_in(worksheet_response.body, 'KeyAttr' => 'name')
=> {"totalResults"=>["1"], "category"=>[{"term ... [ snip ]
# And pretty-print it
irb(main):047:0> pp worksheet_data
{"totalResults"=>["1"],
"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#worksheet",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"title"=>[{"type"=>"text", "content"=>"blank"}],
"author"=>
[{"name"=>["test.api.jhartmann"],
"email"=>["test.api.jhartmann@gmail.com"]}],
"startIndex"=>["1"],
"id"=>
["http://spreadsheets.google.com/feeds/worksheets/o04927555739056712307.3387874275736238738/private/full"],
"entry"=>
[{"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#worksheet",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"title"=>[{"type"=>"text", "content"=>"Sheet 1"}],
"rowCount"=>["100"],
"colCount"=>["20"],
"id"=>
["http://spreadsheets.google.com/feeds/worksheets/o04927555739056712307.3387874275736238738/private/full/od6"],
"content"=>{"type"=>"text", "content"=>"Sheet 1"},
"link"=>
[{"href"=>
"http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full",
"rel"=>"http://schemas.google.com/spreadsheets/2006#listfeed",
"type"=>"application/atom+xml"},
{"href"=>
"http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full",
"rel"=>"http://schemas.google.com/spreadsheets/2006#cellsfeed",
"type"=>"application/atom+xml"},
[ snip: cutting off the rest of the XML ]
如您所見，我們現在可以找到存取 listFeed 和 cellsFeed 的連結 (highlighted above)。在深入探討 listFeed 之前，請允許我快速說明範例試算表中目前有哪些資料，這樣您就會知道我們要尋找的內容：
我們的試算表非常簡單，如下所示：
| language | 網站 |
|---|---|
| Java | http://java.com |
| php | http://php.net |
以下是 listFeed 中的資料：
irb(main):048:0> listfeed_uri = \
irb(main):049:0* worksheet_data["entry"][0]["link"][0]["href"]
=> "http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full"
irb(main):050:0> response = get_feed(listfeed_uri, headers)
=> #<Net::HTTPOK 200 OK readbody=true>
irb(main):051:0> listfeed_doc = \
irb(main):052:0* XmlSimple.xml_in(response.body, 'KeyAttr' => 'name')
=> {"totalResults"=>["2"], "category"=>[{"term" ... [ snip ]
# Again we parse the XML and then pretty print it
irb(main):053:0> pp listfeed_doc
{"totalResults"=>["2"],
"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#list",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"title"=>[{"type"=>"text", "content"=>"Programming language links"}],
"author"=>
[{"name"=>["test.api.jhartmann"],
"email"=>["test.api.jhartmann@gmail.com"]}],
"startIndex"=>["1"],
"id"=>
["http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full"],
"entry"=>
[{"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#list",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"language"=>["java"],
"title"=>[{"type"=>"text", "content"=>"ruby"}],
"website"=>["http://java.com"],
"id"=>
["http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cn6ca"],
"content"=>
{"type"=>"text", "content"=>"website: http://java.com"},
"link"=>
[{"href"=>
"http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cn6ca",
"rel"=>"self",
"type"=>"application/atom+xml"},
{"href"=>
"http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cn6ca/1j81anl6096",
"rel"=>"edit",
"type"=>"application/atom+xml"}],
"updated"=>["2008-03-20T22:19:51.739Z"]},
{"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#list",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"language"=>["php"],
"title"=>[{"type"=>"text", "content"=>"php"}],
"website"=>["http://php.net"],
"id"=>
["http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cokwr"],
"content"=>{"type"=>"text", "content"=>"website: http://php.net"},
[ snip ]
如您所見，listFeed 會為每個資料列建立項目，藉此傳回工作表的內容。系統會假設試算表的第一列包含儲存格標題，然後根據該列中的資料動態產生 XML 標題。查看實際的 XML 即可進一步瞭解：
<?xml version='1.0' encoding='UTF-8'?><feed [ snip namespaces ]> <id>http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full</id> <updated>2008-03-20T22:19:51.739Z</updated> <category scheme='http://schemas.google.com/spreadsheets/2006' term='http://schemas.google.com/spreadsheets/2006#list'/> <title type='text'>Programming language links</title> [ snip: cutting out links and author information ] <entry> <id>http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cn6ca</id> [ snip: updated and category ] <title type='text'>java</title> <content type='text'>website: http://java.com</content> <link rel='self' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cn6ca'/> <link rel='edit' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cn6ca/1j81anl6096'/> <gsx:language>java</gsx:language> <gsx:website>http://java.com</gsx:website> </entry> <entry> <id>http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cokwr</id> [ snip: updated and category ] <title type='text'>php</title> <content type='text'>website: http://php.net</content> <link rel='self' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cokwr'/> <link rel='edit' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full/cokwr/41677fi0nc'/> <gsx:language>php</gsx:language> <gsx:website>http://php.net</gsx:website> </entry> </feed>
為了快速比較，我們來看看 cellsFeed 中如何呈現相同資訊：
# Extract the cellfeed link
irb(main):054:0> cellfeed_uri = \
irb(main):055:0* worksheet_data["entry"][0]["link"][1]["href"]
=> "http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full"
irb(main):056:0> response = \
irb(main):057:0* get_feed(cellfeed_uri, headers)
=> #<Net::HTTPOK 200 OK readbody=true>
# Parse into datastructure and print
irb(main):058:0> cellfeed_doc = \
irb(main):059:0* XmlSimple.xml_in(response.body, 'KeyAttr' => 'name')
=> {"totalResults"=>["6"], [ snip ]
irb(main):060:0> pp cellfeed_doc
{"totalResults"=>["6"],
"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#cell",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"title"=>[{"type"=>"text", "content"=>"Programming language links"}],
"rowCount"=>["101"],
"colCount"=>["20"],
"author"=>
[{"name"=>["test.api.jhartmann"],
"email"=>["test.api.jhartmann@gmail.com"]}],
"startIndex"=>["1"],
"id"=>
["http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full"],
"entry"=>
[{"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#cell",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"cell"=>
[{"col"=>"1",
"row"=>"1",
"content"=>"language",
"inputValue"=>"language"}],
"title"=>[{"type"=>"text", "content"=>"A1"}],
"id"=>
["http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R1C1"],
"content"=>{"type"=>"text", "content"=>"language"},
"link"=>
[{"href"=>
"http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R1C1",
"rel"=>"self",
"type"=>"application/atom+xml"},
{"href"=>
"http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R1C1/8srvbs",
"rel"=>"edit",
"type"=>"application/atom+xml"}],
"updated"=>["2008-03-20T22:19:51.739Z"]},
[ snip ]
如您所見，系統會傳回 6 個項目，每個儲存格各有一個項目。我已將儲存格 A1 以外的所有輸出內容截斷，該儲存格包含「language」一詞。請注意上方顯示的「編輯」連結。這個連結的結尾包含版本字串 (8srvbs)。更新儲存格資料時，版本字串非常重要，我們會在本文結尾進行這項操作。確保更新不會遭到覆寫。每當您發出 PUT 要求更新儲存格資料時，都必須在要求中加入儲存格的最新版本字串。每次更新後，系統都會傳回新的版本字串。
將內容發布至 listFeed
如要發布內容，首先需要 listFeed 的 POST 連結。要求清單動態消息時，系統會傳回這個連結。其中會包含網址 http://schemas.google.com/g/2005#post，做為 rel 屬性的值。您需要剖析這個連結元素，並擷取其 href 屬性。首先，我們會建立一個小型方法，方便發布內容：
irb(main):061:0> def post(uri, data, headers) irb(main):062:1> uri = URI.parse(uri) irb(main):063:1> http = Net::HTTP.new(uri.host, uri.port) irb(main):064:1> return http.post(uri.path, data, headers) irb(main):065:1> end => nil # Set up our POST url irb(main):066:0> post_url = \ irb(main):067:0* "http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full" => "http://spreadsheets.google.com/feeds/list/o04927555739056712307.3387874275736238738/od6/private/full" # We must use 'application/atom+xml' as MIME type so let's change our headers # which were still set to 'application/x-www-form-urlencoded' when we sent our # ClientLogin information over https irb(main):068:0> headers["Content-Type"] = "application/atom+xml" => "application/atom+xml" # Setting up our data to post, using proper namespaces irb(main):069:0> new_row = \ irb(main):070:0* '<atom:entry xmlns:atom="http://www.w3.org/2005/Atom">' << irb(main):071:0* '<gsx:language xmlns:gsx="http://schemas.google.com/spreadsheets/2006/extended">' << irb(main):072:0* 'ruby</gsx:language>' << irb(main):073:0* '<gsx:website xmlns:gsx="http://schemas.google.com/spreadsheets/2006/extended">' << irb(main):074:0* 'http://ruby-lang.org</gsx:website>' << irb(main):075:0* '</atom:entry>' => "<atom:entry xmlns:atom=\"http://www.w3.org/2005/Atom\"><gsx:language ... [ snip ] # Performing the post irb(main):076:0> post_response = post(post_url, new_row, headers) => #<Net::HTTPCreated 201 Created readbody=true>
狀態 201 表示發布成功。
使用 cellsFeed 更新內容
從文件中，我們可以看到儲存格動態消息偏好對現有內容發出 PUT 要求。但由於我們稍早從 cellsFeed 擷取的資訊已經在實際的試算表中，因此要如何新增資訊？我們只需要針對要輸入資料的每個空白儲存格提出要求。下列程式碼片段說明如何擷取空白儲存格 R5C1 (第 5 列第 1 欄)，我們要在其中插入 Python 程式設計語言的相關資訊。
原始變數 cellfeed_uri 只包含 cellfeed 的 URI。現在我們要附加要編輯的儲存格，並取得該儲存格的版本字串以進行編輯：
# Set our query URI irb(main):077:0> cellfeed_query = cellfeed_uri + '/R5C1' => "http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R5C1" # Request the information to extract the edit link irb(main):078:0> cellfeed_data = get_feed(cellfeed_query, headers) => #<Net::HTTPOK 200 OK readbody=true> irb(main):079:0> cellfeed_data.body => "<?xml version='1.0' encoding='UTF-8'?>
<entry xmlns='http://www.w3.org/2005/Atom' xmlns:gs='http://schemas.google.com/spreadsheets/2006' xmlns:batch='http://schemas.google.com/gdata/batch'>
<id>http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R5C1</id>
<updated>2008-03-24T21:55:36.462Z</updated>
<category scheme='http://schemas.google.com/spreadsheets/2006' term='http://schemas.google.com/spreadsheets/2006#cell'/>
<title type='text'>A5</title>
<content type='text'>
</content>
<link rel='self' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R5C1'/>
<link rel='edit' type='application/atom+xml' href='http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R5C1/47pc'/>
<gs:cell row='5' col='1' inputValue=''>
</gs:cell>
</entry>"
如上方的程式碼清單所示，版本字串為 47pc。(你可能需要捲動至最右側)。為簡化作業，請建立便利方法，取得我們感興趣的任何儲存格的版本字串：
irb(main):080:0> def get_version_string(uri, headers=nil)
irb(main):081:1> response = get_feed(uri, headers)
irb(main):082:1> require 'rexml/document'
irb(main):083:1> xml = REXML::Document.new response.body
irb(main):084:1> edit_link = REXML::XPath.first(xml, '//[@rel="edit"]')
irb(main):085:1> edit_link_href = edit_link.attribute('href').to_s
irb(main):086:1> return edit_link_href.split(/\//)[10]
irb(main):087:1> end
=> nil
# A quick test
irb(main):088:0> puts get_version_string(cellfeed_query, headers)
47pc
=> nil
同時，我們也可以編寫方法來執行 PUT 要求，或者更理想的做法是，編寫方法來執行整個批次更新。我們的函式會採用雜湊陣列，其中包含下列變數：
:batch_id- 每項批次要求的專屬 ID。:cell_id：要更新的儲存格 ID，格式為 R#C#，其中儲存格 A1 會表示為 R1C1。:data：要插入的資料。
irb(main):088:0> def batch_update(batch_data, cellfeed_uri, headers)
irb(main):089:1> batch_uri = cellfeed_uri + '/batch'
irb(main):090:1> batch_request = <<FEED
irb(main):091:1" <?xml version="1.0" encoding="utf-8"?> \
irb(main):092:1" <feed xmlns="http://www.w3.org/2005/Atom" \
irb(main):093:1" xmlns:batch="http://schemas.google.com/gdata/batch" \
irb(main):094:1" xmlns:gs="http://schemas.google.com/spreadsheets/2006" \
irb(main):095:1" xmlns:gd="http://schemas.google.com/g/2005">
irb(main):096:1" <id>#{cellfeed_uri}</id>
irb(main):097:1" FEED
irb(main):098:1> batch_data.each do |batch_request_data|
irb(main):099:2* version_string = get_version_string(cellfeed_uri + '/' + batch_request_data[:cell_id], headers)
irb(main):100:2> data = batch_request_data[:data]
irb(main):101:2> batch_id = batch_request_data[:batch_id]
irb(main):102:2> cell_id = batch_request_data[:cell_id]
irb(main):103:2> row = batch_request_data[:cell_id][1,1]
irb(main):104:2> column = batch_request_data[:cell_id][3,1]
irb(main):105:2> edit_link = cellfeed_uri + '/' + cell_id + '/' + version_string
irb(main):106:2> batch_request<< <<ENTRY
irb(main):107:2" <entry>
irb(main):108:2" <gs:cell col="#{column}" inputValue="#{data}" row="#{row}"/>
irb(main):109:2" <batch:id>#{batch_id}</batch:id>
irb(main):110:2" <batch:operation type="update" />
irb(main):111:2" <id>#{cellfeed_uri}/#{cell_id}</id>
irb(main):112:2" <link href="#{edit_link}" rel="edit" type="application/atom+xml" />
irb(main):113:2" </entry>
irb(main):114:2" ENTRY
irb(main):115:2> end
irb(main):116:1> batch_request << '</feed>'
irb(main):117:1> return post(batch_uri, batch_request, headers)
irb(main):118:1> end
=> nil
# Our sample batch data to insert information about the Python programming language into our worksheet
irb(main):119:0> batch_data = [ \
irb(main):120:0* {:batch_id => 'A', :cell_id => 'R5C1', :data => 'Python'}, \
irb(main):121:0* {:batch_id => 'B', :cell_id => 'R5C2', :data => 'http://python.org' } ]
=> [{:cell_id=>"R5C1", :data=>"Python", :batch_id=>"A"}=>{:cell_id=>"R5C2", :data=>"http://python.org", :batch_id=>"B"}]
# Perform the update
irb(main):122:0> response = batch_update(batch_data, cellfeed_uri, headers)
=> #<Net::HTTPOK 200 OK readbody=true>
# Parse the response.body XML and print it
irb(main):123:0> response_xml = XmlSimple.xml_in(response.body, 'KeyAttr' => 'name')
=> [ snip ]
irb(main):124:0> pp response_xml
{"title"=>[{"type"=>"text", "content"=>"Batch Feed"}],
"xmlns:atom"=>"http://www.w3.org/2005/Atom",
"id"=>
["http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full"],
"entry"=>
[{"status"=>[{"code"=>"200", "reason"=>"Success"}],
"category"=>
[{"term"=>"http://schemas.google.com/spreadsheets/2006#cell",
"scheme"=>"http://schemas.google.com/spreadsheets/2006"}],
"cell"=>
[{"col"=>"1", "row"=>"5", "content"=>"Python", "inputValue"=>"Python"}],
"title"=>[{"type"=>"text", "content"=>"A5"}],
"id"=>
["http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R5C1",
"A"],
"operation"=>[{"type"=>"update"}],
"content"=>{"type"=>"text", "content"=>"Python"},
"link"=>
[{"href"=>
"http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R5C1",
"rel"=>"self",
"type"=>"application/atom+xml"},
{"href"=>
"http://spreadsheets.google.com/feeds/cells/o04927555739056712307.3387874275736238738/od6/private/full/R5C1/49kwzg",
"rel"=>"edit",
"type"=>"application/atom+xml"}],
"updated"=>["2008-03-27T15:48:48.470Z"]},
[ snip ]
如您所見，我們已收到 200 OK 回應碼，因此批次要求成功。剖析回應 XML 後，我們可以看到系統會針對 response_data 陣列中設定的每個 :batch_id 傳回個別訊息。如要進一步瞭解批次處理，請參閱 GData 中的批次處理說明文件。
結論
如您所見，使用 Ruby 的互動式殼層來試用 Google Data API 非常簡單。我們可以使用 listFeed 和 cellsFeed 存取試算表和工作表。此外，我們也使用 POST 要求插入了一些新資料，然後編寫方法來執行批次更新，程式碼只有約 120 行。從這個時間點開始，將部分簡單方法包裝到類別中，並建構可重複使用的架構，應該不會太難。
如果您對如何搭配使用這些工具與喜愛的 Google Data API 有任何疑問，歡迎加入討論群組。
如需上述程式碼範例的類別檔案，請前往 http://code.google.com/p/google-data-samples-ruby