使用 pymongo 仅从 mongodb 中查找特定密钥

Question

I have written this code and I want to check only for a key named Virtual_Machines . I have data in the following form. I only want to check if Virtual_Machines is there then don't upload data again.

  {
          "Virtual_Machines": {
               "Debian": {
                    "VM_Name": "Debian",
                    "VM_Location": "eastus",
                    "VM_Disk_Name": "Debian_OsDisk_1_b890f5f5c42647549c881c0706b85201",
                    "VM_Publisher_Info": {
                         "publisher": "debian",
                         "offer": "debian-11",
                         "sku": "11-gen2",
                         "version": "latest"
                    },
                    "Vm_Disk_Type": "Standard_D2s_v3",
                    "VM_Encryption": null
               },
               "Ubuntu": {
                    "VM_Name": "Ubuntu",
                    "VM_Location": "eastus",
                    "VM_Disk_Name": "Ubuntu_disk1_0610e0fde49b481490ef0a069a03b460",
                    "VM_Publisher_Info": {
                         "publisher": "canonical",
                         "offer": "0001-com-ubuntu-server-focal",
                         "sku": "20_04-lts-gen2",
                         "version": "latest"
                    },
                    "Vm_Disk_Type": "Standard_D2s_v3",
                    "VM_Encryption": null
               }
          }
     },

My code is but it is giving output as None .

db = client['Audit']
vms = db['virtual_machine']
vm = json.dumps(vm)
vmachine = vms.find_one({"Virtual_Machine"},{'_id':0})    

print(vmachine)

Answer 1

The first parameter in find_one() must be a dict . You are getting your error because you are passing {"Virtual_Machine"} which python interprets as a set https://docs.python.org/3/library/stdtypes.html#set

If you want to check that a key exists or not, regardless of its value, use the $exists operator. https://www.mongodb.com/docs/manual/reference/operator/query/exists/

vms.find_one({'Virtual_Machines': {'$exists': True}}, {'_id':0})