ruby - POST(而非 GET)维基数据查询

Question

我正在关注 these instructions提交 SPARQL 查询，首选 POST 方法，因为查询可能很长。但即使 GET 有效，它似乎也失败了 - 有什么方法可以使 POST 查询有效？

sparql = <<END
SELECT ?item ?itemLabel 
WHERE 
{
    ?item wdt:P31 wd:Q146.
    SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
}
END

# Fails with 405 Not writable
resp = Excon.post('https://query.wikidata.org/sparql', body: "query=#{URI::encode(sparql)}")
puts resp.status, resp.body

# Works with 200
resp = Excon.get("https://query.wikidata.org/sparql?query=#{URI::encode(sparql)}")
puts resp.status, resp.body

我也试过发送 "Content-Type"=> "application/x-www-form-urlencoded"，但没有成功。

Answer 1

感谢上面的评论者展示了工作示例。我根据所有明显的组合做了一些进一步的检查，如下所示。

总结:

• 如果 GET 很短且可能被重用(因为 GET 查询已缓存)，请使用 GET
• 确保您发送了一个 user-agent header ，并注意某些库默认情况下不会包含一个 header (否则它会返回无法解释的 403)
• 对于 POST，最好和最简单的(在我看来)是将 SPARQL 查询作为整个正文发送，“content-type”为“application/sparql-query”，此处不需要对查询进行编码。您也可以使用“content-type”作为“application/x-www-form-urlencoded”的表单语法，并确保查询已编码。

require 'excon'

# any arbitrary query   
sparql = 'SELECT ?item ?itemLabel WHERE { ?item wdt:P31 wd:Q146.  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". } }'

# SUCCESS!
resp = Excon.get("https://query.wikidata.org/sparql?query=#{URI::encode(sparql)}")
puts "GET", resp.status, resp.body[0,100], "\n"

# FAIL! 403 (need user agent)
headers = { "Content-Type" => "application/sparql-query" }
resp= Excon.post('https://query.wikidata.org/sparql', body: sparql, headers: headers)
puts "POST sparql-query", resp.status, resp.body[0,100], "\n"

# SUCCESS!
headers = { "Content-Type" => "application/sparql-query", "User-Agent" => "Ruby 2.6.4" }
resp= Excon.post('https://query.wikidata.org/sparql', body: sparql, headers: headers)
puts "POST sparql-query with user-agent", resp.status, resp.body[0,100], "\n"

# FAIL! 403 (need user agent)
headers = { "Content-Type" => "application/x-www-form-urlencoded" }
resp = Excon.post('https://query.wikidata.org/sparql', body: "query=#{URI::encode(sparql)}", headers: headers)
puts "POST form", resp.status, resp.body[0,100], "\n"

# SUCCESS!
headers = { "Content-Type" => "application/x-www-form-urlencoded", "User-Agent" => "Ruby 2.6.4" }
resp = Excon.post('https://query.wikidata.org/sparql', body: "query=#{URI::encode(sparql)}", headers: headers)
puts "POST form with user-agent", resp.status, resp.body[0,100], "\n"

# FAIL! 405 (need encoding)
resp = Excon.post('https://query.wikidata.org/sparql', body: "query=#{URI::encode(sparql)}")
puts "POST plain", resp.status, resp.body[0,100], "\n"

# FAIL! 405 (need encoding)
headers = { "User-Agent" => "Ruby 2.6.4" }
resp = Excon.post('https://query.wikidata.org/sparql', body: "query=#{URI::encode(sparql)}", headers: headers)
puts "POST plain with user-agent", resp.status, resp.body[0,100], "\n"

更多信息

• SPARQL 1.1 Protocol
• Phabricator issue
• Wikimedia User-Agent policy