Fetching Data based on conditions using pymongo

Question

I am trying to fetch data based on filter based queries. Right now I am using

 filter_stuff = {'url': 1, 'organization_name': 1, 'hum_pred':1, 'ml_pred':1, '_id': 0}
 myData = list(crawlcol.find({'hum_pred': 'null'}, filter_stuff))

This will fetch data where hum_pred have values null.

hum_pred and ml_pred will have values valid invalid or null

How is it possible to fetch data which has field values hum_pred is null and ml_pred is valid or invalid

sample data

[
 {"url":"www.example1.com","organization_name":"abc","ml_pred":"Valid", "hum_pred":"invalid"},
 {"url":"www.example2.com","organization_name":"gvg","ml_pred":"Invalid", "hum_pred":"null"},
 {"url":"www.example3.com","organization_name":"hsg","ml_pred":"null", "hum_pred":"null"},
 {"url":"www.example4.com","organization_name":"hga","ml_pred":"Valid", "hum_pred":"valid"},
 {"url":"www.example5.com","organization_name":"tre","ml_pred":"Invalid", "hum_pred":"valid"}
 ]

Expected Output

[{"url":"www.example2.com","organization_name":"gvg","ml_pred":"Invalid", "hum_pred":"null"}]

You can specify multiple conditions on multiple fields using $or and $and logical query operators. — prasad_
– prasad_, Commented Apr 14, 2022 at 10:15
@prasad_ Thankyou for the response. Can you give me an example — imhans4305
– imhans4305, Commented Apr 14, 2022 at 10:19
Please feel free to refer the MongoDB Manual, for the usage and examples for the query operators. — prasad_
– prasad_, Commented Apr 14, 2022 at 10:21
I appied in this way list(crawlcol.find({$and: [{$or: [{"ml_pred": "Valid"},{"ml_pred": "Invalid"}]}],{"hum_pred": "null"}}, filter_stuff)) but I am getting an error SyntaxError: invalid syntax — imhans4305
– imhans4305, Commented Apr 14, 2022 at 10:56
Also, see PyMongo documentation for writing queries with Python specific syntax. With Python code one of the requirements is that the operators and field names must be within quotes; for example "$or", 'hum_pred', .... — prasad_
– prasad_, Commented Apr 14, 2022 at 11:02

imhans4305 · Accepted Answer · 2022-04-14 11:06:02Z

1

The query will be like

myData = list(crawlcol.find({"$and": [{"ml_pred": {"$ne": "null"}},{"hum_pred": {"$eq": "null"}}]}))

answered Apr 14, 2022 at 11:06

imhans4305

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Takis · Accepted Answer · 2022-04-14 12:23:56Z

1

Query

you have strings for example "null", so strings are used for null
to check if equal with one of multiple values we can use $or and $eq or $in like bellow ($in is more compact for this use)

*if you have only 3 possible values for ml_pred the @imhans4305 answer is even shorter, so go for the other i think, this is how you could do it in general case.

Playmongo

find({"hum_pred": "null","ml_pred": {"$in": ["Valid", "Invalid"]}})

edited Apr 14, 2022 at 12:23

answered Apr 14, 2022 at 12:17

Takis

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1 Comment

imhans4305 Over a year ago

Thaank for the reply. Please upvote the question too

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