用 Python 解析复杂的 JSON 对象：搜索特定的键/值对

Question

General question : how can I search a specific key:value pair in a JSON using Python?

Details for the specific case : I'm reading ~ 45'000 JSON objects, each one of them look like this one .
As you can see, inside every JSON there are several dictionaries that have the same keys (but different values): "facetName , "facetLabel" , "facetValues" .
I'm interested in the dictionary that starts with "facetName": "soggettof" , that goes like:

{
  "facetName": "soggettof",
  "facetLabel": "Soggetto",
  "facetValues": [
    [
      "chiesa - storia - documenti",
      "chiesa - storia - documenti",
      "1"
    ],
    [
      "espiazione - mare mediterraneo <bacino> - antichita - congressi - munster - 1999",
      "espiazione - mare mediterraneo <bacino> - antichita - congressi - munster - 1999",
      "1"
    ],
    [
      "lega rossa combattenti - storia",
      "lega rossa combattenti - storia",
      "1"
    ],
    [
      "pavia - storia ecclesiastica - origini-sec. 12.",
      "pavia - storia ecclesiastica - origini-sec. 12.",
      "1"
    ],
    [
      "pavia <diocesi> - storia - origini-sec. 12.",
      "pavia <diocesi> - storia - origini-sec. 12.",
      "1"
    ],
    [
      "persia - sviluppo economico - 1850-1900 - fonti diplomatiche inglesi",
      "persia - sviluppo economico - 1850-1900 - fonti diplomatiche inglesi",
      "1"
    ]

Please note, that not all the JSON objects have that.

How can I grab the values of the facetValues list, but only in the dictionary that I'm interested in?

Answer 1

I found your question a little confusing, partially because the data shown in it was not really the JSON-object you needed to extract the information from—but instead was just an example of a sub-JSON-object you wanted to extract it from. Fortunately you had a link to the outermost container JSON-object (even though the data in corresponding sub-JSON-object in it was different). Here's the data from that link:

json_obj = {"numFound":1,"start":0,"rows":3,"briefRecords":[{"progressivoId":0,"codiceIdentificativo":"IT\\ICCU\\LO1\\0120590","autorePrincipale":"Savoia, Carlo","titolo":"Per la inaugurazione dell'Asilo infantile Strozzi nei locali della caserma Filippini già convento della Vittoria / parole di mons. Carlo Savoia","pubblicazione":"Mantova : Tip. Eredi Segna, 1870","livello":"Monografia","tipo":"Testo a stampa","numeri":[],"note":[],"nomi":[],"luogoNormalizzato":[],"localizzazioni":[],"citazioni":[]}],"facetRecords":[{"facetName":"level","facetLabel":"Livello bibliografico","facetValues":[["Monografia","m","1"]]},{"facetName":"tiporec","facetLabel":"Tipo di documento","facetValues":[["Testo a stampa","a","1"]]},{"facetName":"nomef","facetLabel":"Autore","facetValues":[["savoia, carlo","savoia, carlo","1"]]},{"facetName":"soggettof","facetLabel":"Soggetto","facetValues":[["mantova - asili infantili","mantova - asili infantili","1"]]},{"facetName":"luogof","facetLabel":"Luogo di pubblicazione","facetValues":[["mantova","mantova","1"]]},{"facetName":"lingua","facetLabel":"Lingua","facetValues":[["italiano","ita","1"]]},{"facetName":"paese","facetLabel":"Paese","facetValues":[["italia","it","1"]]}]}

It's important to have this outermost container because it is through it you will have to drill-down to the portion you want. Once you have the actual data It's often helpful to reformat it to make its structure clear. You can do this by hand, or have the computer do it via a print(json.dumps(json_obj, indent=2)) , although the results from that can sometimes have a little too much white space in them (which can be counterproductive).

That being the case here, below is the more succinct version I came up doing it manually that still let's me see the overall layout of the data:

json_obj = {"numFound" : 1,
             "start" : 0,
             "rows" : 3,
             "briefRecords" : [
                {"progressivoId" : 0,
                 "codiceIdentificativo" : "IT\\ICCU\\LO1\\0120590",
                 "autorePrincipale" : "Savoia, Carlo",
                 "titolo" : "Per la inaugurazione dell'Asilo infantile Strozzi nei locali della caserma Filippini già convento della Vittoria / parole di mons. Carlo Savoia",
                 "pubblicazione" : "Mantova : Tip. Eredi Segna, 1870",
                 "livello" : "Monografia",
                 "tipo" : "Testo a stampa",
                 "numeri" : [],
                 "note" : [],
                 "nomi" : [],
                 "luogoNormalizzato" : [],
                 "localizzazioni" : [],
                 "citazioni" : []
                }
             ],
             "facetRecords" : [
                {"facetName" : "level" ,
                 "facetLabel" : "Livello bibliografico" ,
                 "facetValues" : [["Monografia" , "m" , "1"]]},
                {"facetName" : "tiporec" ,
                 "facetLabel" : "Tipo di documento" ,
                 "facetValues" : [["Testo a stampa" , "a" , "1"]]},
                {"facetName" : "nomef" ,
                 "facetLabel" : "Autore" ,
                 "facetValues" : [["savoia, carlo" , "savoia, carlo" , "1"]]},
                {"facetName" : "soggettof" ,
                 "facetLabel" : "Soggetto" ,
                 "facetValues" : [["mantova - asili infantili" , "mantova - asili infantili" , "1"]]},
                {"facetName" : "luogof" ,
                 "facetLabel" : "Luogo di pubblicazione" ,
                 "facetValues" : [["mantova" , "mantova" , "1"]]},
                {"facetName" : "lingua" ,
                 "facetLabel" : "Lingua" ,
                 "facetValues" : [["italiano" , "ita" , "1"]]},
                {"facetName" : "paese" ,
                 "facetLabel" : "Paese" ,
                 "facetValues" : [["italia" , "it" , "1"]]}
             ]
            }

Once you have something like this, it's usually fairly easy to determine what code is needed. In this case it's:

target_facet_name = "soggettof"

for record in json_obj["facetRecords"]:
    if record["facetName"] == target_facet_name:
        for value in record["facetValues"]:
            print(value)

Since facetRecords is a list , a linear search through them as shown is required to find the one(s) wanted.