我有一个包含多个JSON文件的目录。每个JSON文件都有一个JSON结构（每个结构中有3个字典元素）。我想读取每个JSON文件，并将字典附加到一个dictionary中-一个主dictionary，其中包含所有字典。这是我的代码：

def json_read:
    pathToDir = '/path/to/directory'
    json_mstr = {}

    for file_name in [file for file in os.listdir(pathToDir) if file.endswith('.json')]:
        with open(pathToDir + file_name) as input_file:
            print(file_name)
            json_str = json.load(input_file)
            json_mstr.update(json_str)

    print(len(json_mstr))
    
    return json_mstr

当我打印长度时，我只看到3作为最终主dictionary的长度，并且只看到主dictionary中最后一个JSON文件的字典内容。不知道为什么update()在每次读取文件后都会重置字典？

注意：每个文件中JSON的示例结构如下：

{
  "resourceType": "Single",
  "type": "transaction",
  "entry": [
    {
      "fullUrl": "urn:uuid",
      "resource": {
        "resourceType": "Employee",
        "id": "4cb1a87c",
        "text": {
          "status": "generated",
          "div": "generated"
        },
        "extension": [],
        "identifier": [
          {
            "system": "https://github.com",
            "value": "43f123441901"
          }
        ],
        "name": [
          {
            "use": "official",
            "family": "Shields52",
            "given": [
              "Aaro97"
            ],
            "prefix": [
              "Mr."
            ]
          }
        ],
        "maritalStatus": {
          "coding": [
            {
              "system": "MaritalStatus",
              "code": "M",
              "display": "M"
            }
          ],
          "text": "M"
        },
        "multipleBirthBoolean": false
      },
      "request": {
        "method": "POST",
        "url": "User"
      }
    },
{
      "fullUrl": "f411764e1f01",
      "resource": {
        "resourceType": "Claim",
        "id": "411764e1f01",
        "status": "active",
        "type": {
          "coding": [
            {
              "system": "type",
              "code": "Company"
            }
          ]
        },
        "use": "claim",
        "employee": {
          "reference": "1141dfb308"
        },
        "billablePeriod": {
          "start": "2009-12-24T16:42:36-05:00",
          "end": "2009-12-24T16:57:36-05:00"
        },
        "created": "2009-12-24T16:57:36-05:00",
        "provider": {
          "reference": "7e31e2b3feb"
        },
        "priority": {
          "coding": [
            {
              "system": "Employee",
              "code": "normal"
            }
          ]
        },
        "procedure": [
          {
            "sequence": 1,
            "procedureReference": {
              "reference": "58f373a0a0e"
            }
          }
        ],
        "insurance": [
          {
            "sequence": 1,
            "focal": true,
            "coverage": {
              "display": "Employer"
            }
          }
        ],
        "item": [
          {
            "sequence": 1,
            "productOrService": {
              "coding": [
                {
                  "system": "http://comp1.info/",
                  "code": "1349003",
                  "display": "check up"
                }
              ],
              "text": "check up"
            },
            "encounter": [
              {
                "reference": "bc0a5705f6"
              }
            ]
          },
          {
            "sequence": 2,
            "procedureSequence": [
              1
            ],
            "productOrService": {
              "coding": [
                {
                  "system": "http://comp.info",
                  "code": "421000124101",
                  "display": "Documentation"
                }
              ],
              "text": "Documentation"
            },
            "net": {
              "value": 116.60,
              "currency": "USD"
            }
          }
        ],
        "total": {
          "value": 163.7,
          "currency": "USD"
        }
      },
      "request": {
        "method": "POST",
        "url": "Employee"
      }
    }
    ]
}