Find field between two documents with multiple condition in Python

Question

   def method(class, doc): # read and fetch data from coll1 and get required fields
        id = doc['id']
        type = doc['type']
        startdate = doc['startDate']
        endDate = doc['endDate'])
        match = class.mongo_db['coll2'] # match fields in coll1 and coll2 and fetch data from coll2
        target = match.find({'id': id, 'type': type,'startDate':{'$lte': startdate},'endDate':{'$gte': endDate}})
        Data = []
        for data1 in target:
            Data.append(data1)
        if len(Data) == 1:
          ---------------
          ----------
          ----
          --
        else:
          skip

      
      
      

I need to match data from both collections and fetch required data, if two documents got fetched from coll2 then we need to skip else proceed.

I am successful in this with out having an issue:

if coll2 has proper 'endDate' to match, but in some scenarios the the 'endDate' would be 00 then I need to consider it has 20500202 (IF end data was 00) how can I do this in above mongo?

Find query, I am unable to achieve this if 'endDate' is 00

For example, if enddate of coll1 is 20210303, and end date of coll2 is 00, then we should consider it as

(20500202 > 20210303) 

not

(00 > 20210303)`

`

-- source collection coll1
{
    "Id": "ID1",      
    "type": "DATA",
    "startdate": 20200101,
    "endDate": 20200301
}



-- collection coll2 which to match from coll1 ex_1
{
    "Id": "ID1",
    "type": "DATA",
    "startdate": 20200101,
    "endDate": 00,
    "documentId": "DSC0001",
    "documentDesc": "Value document"
}

match id,type,startdate<(coll1 startdate),endDate>(coll1 endDate)

if end date of coll2 is zero then we need to consider it as

(20500202 > 20210301)

not

(00 > 20210303) 

so the desired output needed from coll2 is

{
    "startdate": 20200101,
    "endDate": 0,
    "documentId": "DSC0001",
    "documentDesc": "Value document"
}

-- collection coll2 which to match from coll1 ex_2

{
    "Id": "ID1",
    "type": "DATA",
    "startdate": 20200101,
    "endDate": 20200401,
    "documentId": "DSC0001",
    "documentDesc": "Value document"
}

if endDate of coll2 is in proper format then we can directly consider it as

20200401>20210303

so the desired output needed from coll2 is

{
    "startdate": 20200101,
    "endDate": 0,
    "documentId": "DSC0001",
    "documentDesc": "Value document"
}

Please suggest me how to achieve this

thanks in advance

Answer 1

What you are looking for is possible only in MongoDB Aggregation.

The below code is what you are looking for if my understanding is right.

target = match.aggregate([
  {
    "$match": {  # <-- Put all your conditions except for `endDate`
      'id': id, 
      'type': type,
      'startDate':{
        '$lte': startdate
      }
    },
  },
  {
    "$project": {  # <-- Keys you want to be projected from `coll2`
      "documentId": 1,
      "documentDesc": 1,
      "startdate": 1,
      "endDate": {
        "$cond": {
          "if": {
            "$in": [
              "$endDate",
              [  #  <-- Add all your exceptions here
                0,
                "00",
              ]
            ]
          },
          "then": 20500202,
          "else": "$endDate",
        }
      }
    },
  },
  {
    "$match": {  # <-- Add your `endDate` condition here
      "endDate": {
        "$gte": endDate,
      }
    },
  },
])