如何使用 Linq 将 JSON 文件中两个不同位置的数据转换为 C# 字典中的键（字符串）和值（双精度）？

Question

我目前正在尝试从国家统计局 API 下载数据。JSON 的格式为：

{
"@context": "https://cdn.ons.gov.uk/assets/json-ld/context.json",
"dimensions": {
    "geography": {
        "option": {
            "href": "https://api.beta.ons.gov.uk/v1/code-lists/nuts/codes/UKG",
            "id": "UKG"
        }
    },
    "growthrate": {
        "option": {
            "href": "https://api.beta.ons.gov.uk/v1/code-lists/quarterly-index-and-growth-rate/codes/gra",
            "id": "gra"
        }
    },
    "prices": {
        "option": {
            "href": "https://api.beta.ons.gov.uk/v1/code-lists/type-of-prices/codes/cvm",
            "id": "cvm"
        }
    },
    "time": {
        "option": {
            "href": "https://api.beta.ons.gov.uk/v1/code-lists/calendar-years/codes/2018",
            "id": "2018"
        }
    }
},
"limit": 10000,
"links": {
    "dataset_metadata": {
        "href": "https://api.beta.ons.gov.uk/v1/metadata"
    },
    "self": {
        "href": "https://api.beta.ons.gov.uk/v1/datasets/regional-gdp-by-year/editions/time-series/versions//observations?geography=UKG&growthrate=gra&prices=cvm&time=2018&unofficialstandardindustrialclassification=*"
    },
    "version": {
        "href": "https://api.beta.ons.gov.uk/v1"
    }
},
"observations": [
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/C",
                "id": "C",
                "label": "C : Manufacturing"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "0.4"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/O",
                "id": "O",
                "label": "O : Public administration and defence; compulsory social security"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "0.8"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/R",
                "id": "R",
                "label": "R : Arts, entertainment and recreation"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "2.4"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/P",
                "id": "P",
                "label": "P : Education"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "4.2"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/H",
                "id": "H",
                "label": "H : Transportation and storage"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "2.7"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/F",
                "id": "F",
                "label": "F : Construction"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "-0.8"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/K",
                "id": "K",
                "label": "K : Financial and insurance activities"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "3.5"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/M",
                "id": "M",
                "label": "M : Professional, scientific and technical activities"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "1.9"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/I",
                "id": "I",
                "label": "I : Accommodation and food service activities"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "-1.4"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/J",
                "id": "J",
                "label": "J : Information and communication"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "7.4"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/B--E",
                "id": "B--E",
                "label": "B-E : Production"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "0"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/L",
                "id": "L",
                "label": "L : Real estate activities"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "1.2"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/E",
                "id": "E",
                "label": "E : Water supply; sewerage, waste management and remediation activities"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "1.4"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/N",
                "id": "N",
                "label": "N : Administrative and support service activities"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "4.2"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/A--T",
                "id": "A--T",
                "label": "A-T : Total"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "2.1"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/G",
                "id": "G",
                "label": "G : Wholesale and retail trade; repair of motor vehicles and motorcycles"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "3.8"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/B",
                "id": "B",
                "label": "B : Mining and quarrying"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "8.3"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/A",
                "id": "A",
                "label": "A : Agriculture, forestry and fishing"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "-5.2"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/T",
                "id": "T",
                "label": "T : Activities of households as employers; undifferentiated goods and services-producing activities of households for own use"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "26.6"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/D",
                "id": "D",
                "label": "D : Electricity, gas, steam and air conditioning supply"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "-4.6"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/Q",
                "id": "Q",
                "label": "Q : Human health and social work activities"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "4.1"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/G--T",
                "id": "G--T",
                "label": "G-T : Services sector"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "3"
    },
    {
        "dimensions": {
            "UnofficialStandardIndustrialClassification": {
                "href": "https://api.beta.ons.gov.uk/v1/code-lists/sic-unofficial/codes/S",
                "id": "S",
                "label": "S : Other service activities"
            }
        },
        "metadata": {
            "Data Marking": ""
        },
        "observation": "2.4"
    }
],
"offset": 0,
"total_observations": 23

}

我要获取的数据是作为字符串键的“标签”和作为双精度值的“观察”。 然后我试图将其保存在字典中。

我目前使用的代码如下所示：

UnityWebRequest www = UnityWebRequest.Get($"{baseUrl}observations?geography=UKG&growthrate=gra&prices=cvm&time={x}&unofficialstandardindustrialclassification=*");
            yield return www.SendWebRequest();
            if (www.result != UnityWebRequest.Result.Success)
            {
                Debug.Log(www.error);
            }
            else
            {

                OnsApiResult = www.downloadHandler.text;


                var observations = JObject.Parse(OnsApiResult)["observations"];
                var results = from data in observations
                              select
                                new { label = data["dimensions"]["UnofficialStandardIndustrialClassification"]["label"].ToObject<string>(), observation = data["observation"].ToObject<double>() };


                foreach (var item in results)
                {
                    thisYearData.Add(item.label, item.observation);
                }

当我将信息保存为 object 时系统工作，但是当我尝试将数据转换为字符串和双精度时，我收到错误消息：

“FormatException：输入字符串的格式不正确。”

我正在使用 newtonsoft.JSON 和 System.Linq，我也在使用 Unity 游戏引擎。

有人可以帮我吗？ 谢谢你。

Answer 1

我稍微更改了您的代码，对我来说没问题

    var observations = JObject.Parse(OnsApiResult)["observations"];
    var results = observations.Select( data => new {
        label = (string)data["dimensions"]["UnofficialStandardIndustrialClassification"]["label"],
        observation = (double)data["observation"]
        });

Answer 2

你的代码在我这边运行良好......也许你的 JSON 有一些错误......你可以尝试以下命令式方法而不是 LINQ 来获取有关发生的事情的更多信息

foreach(var data in observations)
{
    string label = (string)data["dimensions"]["UnofficialStandardIndustrialClassification"]["label"];
    
    double observation = 0.0;
    if (!double.TryParse((string)data["observation"], out observation))
    {
        // the string observation can not convert to double 
        // log it 
        Console.Error.WriteLine($"ther is problem in json the the value '{data["observation"]}' can not be double");
        continue;
    }
    if (thisYearData.ContainsKey(label))
    {
        // your dictionary alredy has the value 
        Console.Error.WriteLine($"doublicat label : '{label}' alredy exist");
        continue;
    }
    thisYearData.Add(label, observation);    

}

Answer 3

解决了：

我的代码没有任何问题。 我从 ONS 收到的 2012 年数据格式错误。 我从数据中删除了 2012 年，它工作正常。