Question

我已经编写了小型ruby代码来获取发布统计信息，代码正在跟随

begin
  response = conn.get("api/queues")
  statistics = JSON.parse(response.body)

  statistics.each do |qDetails|
    payload = "#{qDetails["name"]}"
    if payload != "aliveness-test"
      puts "#{qDetails["message_stats"]["publish"]}"          
    end             
  end      
rescue Faraday::Error::ConnectionFailed => e
  puts "Connection failed"
end

但是我得到了这个错误

undefined method `[]' for nil:NilClass (NoMethodError)

message_stats json就像这样

{"deliver_get_details"=>{"rate"=>0.0}, "deliver_get"=>1357, "ack_details"=>{"rate"=>0.0}, "ack"=>1357, "redeliver_details"=>{"rate"=>0.0}, "redeliver"=>0, "deliver_no_ack_details"=>{"rate"=>0.0}, "deliver_no_ack"=>0, "deliver_details"=>{"rate"=>0.0}, "deliver"=>1357, "get_no_ack_details"=>{"rate"=>0.0}, "get_no_ack"=>0, "get_details"=>{"rate"=>0.0}, "get"=>0, "publish_details"=>{"rate"=>0.0}, "publish"=>1400}

问题是什么？

Answer 1

对于红宝石＆gt; 2.3，您可以使用@JoinColumn：

@Entity
public class OrderPosition implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @ManyToOne
    @JoinColumn(name = "order_id", referencedColumnName = "id")
    //@Json???
    private Order order;

    //  ...
}

orderPosition = new OrderPosition()
// ...
ObjectMapper objectMapper = new ObjectMapper();
String json = objectMapper.writeValueAsString(orderPosition);
assertThat(json).contains("\"order_id\":");

这将安全地访问//currently selected company $currently-selected-company: company1; //here I set current brand but I want to make it load after rest response. //There are default values for variables below so there won't be any null. @if ($currently-selected-company == company1) { $current-header-text-color: $comp1-color; $logo-right-border-color: $comp1-color; } @else if ($currently-selected-company == company2) { $logo-right-border-color: $company2-color; } @else if ($currently-selected-company == company3) { $currently-selected-color: $company3-color; $current-header-text-color: $company3-color; $selection-color: $company3-color; $main-color: $company3-color; $logo-right-border-color: $company3-color; } //just few properties to visualize the problem

您获得的错误可能是因为dig为零，因此在其上调用qDetails.dig("message_stats", "publish")不起作用

Answer 2

您可以使用ruby-fetch方法从您不确定密钥是否存在的哈希中获取数据。您还可以将默认值设置为返回，而dig如果未找到值则返回nil

qDetails["message_stats"].fetch("publish", "default_value")

另一种方法是使用安全导航操作符（&）：

qDetails["message_stats"]&.[]('publish') # Return nil if not found

如何获取哈希数组ruby中的值

2 个答案: