Using MongoDB to filter and search within an array using both the $in operator and regular

Question

Using MongoDB to filter and search within an array using both the $in operator and regular

My challenge involves working with 2 collections, where I'm attempting to retrieve all records from Coll_A where a specific field (Field1) is not present in Coll_B.

The complicating factor is that the Field1 in

Coll_A</code has trailing white spaces up to a certain length, which are missing in the corresponding collection.</p>

<p>In the query below, the array <code>vals

contains unpadded records, causing inaccurate results when using db.Coll_A.find.

vals = db.Coll_B.find({}, 
                      {"Field1" : 1, _id: 0})
                .map(function(a){
                      return a.Field1;
                    });
db.Coll_A.find({ "Field1": { $nin: vals }});

I've explored using regex to handle whitespace differences, but I'm unsure how to apply it in this scenario. Any help would be greatly appreciated. Thank you.

javascript mongodb

Answer 1

Answer №1

To enhance your code, consider adjusting the return value to an array of regular expressions and implement it with the $nin operator.

Here is a sample code snippet:

var exp = db.Coll_B.find({}, {"Field1" : 1, _id: 0}).map(function(a){
                                 return new RegExp(a.Field1+"\\s*$");
                             });
db.coll_A.find({"Field1":{$nin:exp}});

Note that utilizing the $regex operator within the $nin or $in operators is not supported.

Answer 2

To enhance your code, consider adjusting the return value to an array of regular expressions and implement it with the $nin operator.

Here is a sample code snippet:

var exp = db.Coll_B.find({}, {"Field1" : 1, _id: 0}).map(function(a){
                                 return new RegExp(a.Field1+"\\s*$");
                             });
db.coll_A.find({"Field1":{$nin:exp}});

Note that utilizing the $regex operator within the $nin or $in operators is not supported.

Answer 3

Answer №2

To ensure consistency in the collection, it's recommended to address any data inconsistencies by removing unnecessary white spaces from all records.

If you are unable or unwilling to perform this task directly, an alternative approach would be to utilize a forEach function for manual checking:

var results = [];
db.Collection_A.find({}).forEach(function(item){
   if(item.Field1.trim().indexOf(values) === -1){
     results.push(item);
   }
});

Answer 4

To ensure consistency in the collection, it's recommended to address any data inconsistencies by removing unnecessary white spaces from all records.

If you are unable or unwilling to perform this task directly, an alternative approach would be to utilize a forEach function for manual checking:

var results = [];
db.Collection_A.find({}).forEach(function(item){
   if(item.Field1.trim().indexOf(values) === -1){
     results.push(item);
   }
});

Using MongoDB to filter and search within an array using both the $in operator and regular

Answer №1

Answer №2

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