python - 在 Django 中使用请求解析 JSON

Question

我正在使用 Django 应用程序中的请求进行 API 调用。我不断收到关于名称的关键错误。 json 响应非常大，所以我只选择某些字段来使用。但错误出现在 json 列表中的第一项上。

json 的前几行看起来像这样，

"cards": [
    {
      "name": "Air Elemental",
      "manaCost": "{3}{U}{U}",
      "cmc": 5,
      "colors": [
        "Blue"
      ],
      "type": "Creature — Elemental",
      "types": [
        "Creature"
      ],
      "subtypes": [
        "Elemental"
      ],

在我看来，我正在像这样解析 json，

def graphs(request):
    if request.user.is_authenticated():
        parsedData = []
        req = requests.get('https://api.magicthegathering.io/v1/cards')
        jsonList = []
        jsonList.append(json.loads(req.content.decode()))
        cardData = {}
        for cards in jsonList:
            cardData['name'] = cards['name']
            cardData['manaCost'] = cards['manaCost']
            cardData['colors'] = cards['colors']
            cardData['type'] = cards['type']
            cardData['rarity'] = cards['rarity']
            cardData['set'] = cards['set']
            cardData['text'] = cards['text']
            cardData['flavor'] = cards['flavor']
            cardData['artist'] = cards['artist']
            cardData['power'] = cards['power']
            cardData['toughness'] = cards['toughness']
            cardData['layout'] = cards['layout']
            cardData['multiverseid'] = cards['multiverseid']
            cardData['id'] = cards['id']
        parsedData.append(cardData)
        return render(request, 'graphs/graphs.html', {'data': parsedData})
    else:
        return redirect('index')

错误

KeyError at /graphs/graphs/
'name'

在我看来，我正在像这样访问数据，

 {% for key in cards %}
                      <tr>
                          <td>{{ key.name }}</td>
                          <td>{{ key.manaCost }}</td>
                          <td>{{ key.colors }}</td>
                          <td>{{ key.type }}</td>
                          <td>{{ key.rarity }}</td>
                          <td>{{ key.set }}</td>
                          <td>{{ key.text }}</td>
                          <td>{{ key.flavor }}</td>
                          <td>{{ key.artist }}</td>
                          <td>{{ key.power }}</td>
                          <td>{{ key.toughness }}</td>
                          <td>{{ key.layout }}</td>
                          <td>{{ key.multiverseid }}</td>
                          <td>{{ key.id }}</td>
                      </tr>
                  {% endfor %}

为什么我会收到 key 错误？

Answer 1

当你这样做的时候

json.loads(req.content.decode())

你得到一个字典，一个键，cards .

{'cards': [<list of cards>]}

将其附加到 jsonList 没有意义，因为那时你有，

[{'cards': [<list of cards>]}

当您遍历该列表时，您将获得开始时使用的单个字典。正如我们之前所说，该字典只有一个键，cards。 ，因此当您尝试访问 name 时会出现 key 错误不存在的 key 。

你真的想遍历 [<list of cards>] , 所以设置 jsonList改为该列表。

    req = requests.get('https://api.magicthegathering.io/v1/cards')
    jsonData = json.loads(req.content.decode())
    jsonList = jsonData['cards']
    for cards in jsonList:
        cardData = {}  # move this line inside the loop
        cardData['name'] = cards['name']
        ...
        # make sure this line is inside the loop so that you append
        # every card to parsedData
        parsedData.append(cardData) 

如评论和其他答案中所述，您可以使用请求的 json()简化代码的方法:

    req = requests.get('https://api.magicthegathering.io/v1/cards')
    jsonList = req.json()['cards']
    for cards in jsonList:
        ...