Question

我正在尝试按照ruby RDF gem的文档对图形进行初始化。（http://www.rubydoc.info/gems/rdf/RDF/Graph）

文档提供以下示例：

graph = Graph.new("http://rubygems.org/")

我试过运行这个确切的命令，我得到一个错误（我真的不明白）。（请注意，我在使用本地计算机上的文件时成功加载了图表，所以我认为尝试从http网址加载图表时会遇到一些问题。）

我正在通过命令行界面Gem Thor运行命令。下面是可执行文件，然后返回错误。

档案lbp

#!/usr/bin/env ruby

require 'rdf'
require 'rdf/rdfxml'
require 'rdf/ntriples'
require 'thor'
require 'pry'

class LbpCli < Thor 
  desc "hello", "say hello to NAME"
  def hello(name)
      puts "Hello #{name}!"
  end

  desc "init", "create projectifles dirs in current working directory"
  def init(dir="projectfiles")
      directories = ["#{dir}/Conf", "#{dir}/Textfiles", "#{dir}/citationlists"]
      FileUtils.mkpath(directories)
  end

  desc "projecfile", "make projetfile from SCTA" 
  def projectfile
      graph = RDF::Graph.new("http://rubygems.org")
  end
end

LbpCli.start(ARGV)

projectfile是相关方法。下面是命令运行并返回错误。

文件lbp使用方法projectfile

运行

$ ./lbp projectfile
/Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/rdf-1.1.7/lib/rdf/model/graph.rb:126:in `initialize': Can't apply context unless initialized with `data` supporting contexts (ArgumentError)
    from ./lbp:28:in `new'
    from ./lbp:28:in `projectfile'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/thor-0.19.1/lib/thor/command.rb:27:in `run'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/thor-0.19.1/lib/thor/invocation.rb:126:in `invoke_command'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/thor-0.19.1/lib/thor.rb:359:in `dispatch'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/thor-0.19.1/lib/thor/base.rb:440:in `start'
    from ./lbp:45:in `<main>'

修改

如果我通过明确地创建resource来改变构造：

resource = RDF::Resource(RDF::URI.new("http://rdf.rubyforge.org/"))
graph = RDF::Graph.load(resource)

我收到一个新错误：

bin $ ./lbp projectfile
/Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/rdf-1.1.7/lib/rdf/util/file.rb:66:in `open_file': uninitialized constant RDF::Util::File::OpenSSL (NameError)
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/rdf-1.1.7/lib/rdf/reader.rb:136:in `open'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/rdf-1.1.7/lib/rdf/mixin/mutable.rb:43:in `load'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/rdf-1.1.7/lib/rdf/model/graph.rb:81:in `block in load'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/rdf-1.1.7/lib/rdf/model/graph.rb:131:in `call'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/rdf-1.1.7/lib/rdf/model/graph.rb:131:in `initialize'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/rdf-1.1.7/lib/rdf/model/graph.rb:80:in `new'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/rdf-1.1.7/lib/rdf/model/graph.rb:80:in `load'
    from ./lbp:29:in `projectfile'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/thor-0.19.1/lib/thor/command.rb:27:in `run'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/thor-0.19.1/lib/thor/invocation.rb:126:in `invoke_command'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/thor-0.19.1/lib/thor.rb:359:in `dispatch'
    from /Users/JCWitt/.rvm/gems/ruby-2.2.0@lbp/gems/thor-0.19.1/lib/thor/base.rb:440:in `start'
    from ./lbp:47:in `<main>'

Answer 1

文档提供以下示例：

graph = Graph.new("http://rubygems.org/")

确实，这已经过时了，必须更新文档。加载图表的正确方法如下：

graph = Graph.load("http://rubygems.org/")

但是，这不会加载任何三元组。你可以试试这个：

graph = RDF::Graph.load("http://ruby-rdf.github.io/rdf/etc/doap.nt")

如果我通过显式创建资源来稍微改变构造：

resource = RDF::Resource(RDF::URI.new("http://rdf.rubyforge.org/"))
graph = RDF::Graph.load(resource)

是的，两者都没有三倍，RDF::Resource(RDF::URI.new(...))是多余的，因为RDF::URI是RDF::Resource的子类。我之前展示的负载应该可以胜任。

自述文件中的文档（可在此处找到：http://www.rubydoc.info/github/ruby-rdf/rdf以及其他文档）更清晰一些。我通过示例确认它们与1.1版本一起使用，但显然错过了这个。我将通过并重新检查示例并重新生成文档。

使用ruby rdf.rb gem初始化Graph.new时遇到问题

1 个答案: