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

I am currently trying to download data from the office for national statistics API. The JSON has the format:

{
"@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

}

The data I am trying to get out is the "label" as the string key and the "observation" as the double value. I am then trying to save this within a dictionary.

The code I am currently using looks like this:

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);
                }

the system works when I keep the information as an object, but when I try to convert the data to string and double, I get the error messages:

"FormatException: Input string was not in a correct format."

I am using newtonsoft.JSON, and System.Linq, I am also working on the Unity Game Engine.

Can someone please help me with this? Thank You.

Answer 1

I changed a little your code and it works ok for me

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

Answer 2

Your code is working fine in my side... maybe you have some error in your JSON....you can try the following imperative approach instead of LINQ to get more info about what happen

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

Solved:

There was nothing wrong with my code. The data I was receiving for 2012 from the ONS was badly formatted. I removed the 2012 from the data and it worked fine.