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MongoDB — Updating Documents — 3


  1. UpdateOne
    • db.<collection>.updateOne(filter, update)
    • Example:
      • db.<collection>.updateOne({_id: <id>}, {$set: {<field>: <Value>}})
  2. UpdateMany
    • db.<collection>.updateOne(filter, update)
    • Example:
      • db.<collection>.updateMany({<field1>: <Value1>}, {$set: {<field2>: <Value2>}})
  3. $inc (Incrementing/Decrementing)
    • Incrementing
      • db.<collection>.updateOne({<field1>: <Value>}, {$inc: {<field2>: <n>}})
    • Decrementing
      • db.<collection>.updateOne({<field1>: <Value>}, {$inc: {<field2>: <-n>}})
    • Increment/Decrement one field and update other
      1. db.<collection>.updateOne({<field1>: <Value1>}, {$inc: {<field2>: <n>}, $inc: {<field3>: <Value2>}})
  4. $min — if new value < old value then updates with new value
    • db.<collection>.updateOne({<field1>: <Value>} {$min: {<field2>:<n>}})
  5. $max — if new value > old value then updates with new value
    • db.<collection>.updateOne({<field1>: <Value>} {$max: {<field2>:<n>}})
  6. $max — multiplies value and updates
    • db.<collection>.updateOne({<field1>: <Value>} {$mul: {<field2>:<n>}})
  7. $unset — removes field
    • db.<collection>.updateMany({<field1>: <Value>}, {$unset: {<field2>: ""}})
  8. $rename — rename field
    • db.<collection>.updateMany({}, {$rename: {<field2>: <new field name>}})
      • if field exists, it will be renamed in all documents
  9. $upsert — takes boolean value, default is false, if set true add a document if not found
    • db.<collection>.updateMany({<field1>: <Value1>}, {$set: {<field2>: <Value2>, <field3>: <Value3>}}, {upsert: true})
  10. Update embeded document inside document
    • Wrong Way: db.<documents>.updateMany({$and: [{<field>.<subfield1>:<Value1>}, {<field>.<subfield2>: {$gte: n}}]}, {$set: {}})
    • Right Way: db.<documents>.updateMany({<field>: {$elemMatch: {<subfield1>:<Value1>, <subfield2>: {$gte: n}}}}, {$set: {"<field>.$.<new subfield>": <Value2>}})
  11. Update all matched values from an array of embeded documents
    • db.<collection>.updateMany({<field>: {$gt: <num>}}, {$inc: {"<field>.$[].frequency": <num>}})
      • Updating field inside array of embeded documents
    • db.<collection>.updateMany({<field>: {$gt: <num>}}, {$inc: {"<field>.$[]": <num>}})
      • Updating field inside array
  12. When searching directly for a few embeded documents in an array, entire array is returned. If you want only embeded documents from array that match your need then use the following
    • db.<collection>.updateMany({"<field>.<subfield>": {$gt: <n>}}, {$set: {"<field>.$[ele]<subfield>": <Value>}}, {arrayFilters: [{"ele.<subfield>": {$gt: <n>}}]})
      • First filter and arrayFilters do not have to be equal, even though we used the same in the example
      • First filter is to return documents containing the condition, and arrayFilters, like the name suggests, is to return the embeded documents in the array that matches the condition
      • 'ele' in the example is a name given by us to refer each array element
  13. Adding embeded document or value to an array
    • db.<collection>.updateOne({<field1>:<value1>}, {$push: {<array field>: <embeded document OR value>}})
      • for adding one value or embeded document to the array
    • db.<collection>.updateOne({<field1>:<value1>}, {$push: {<array field>: {$each: [<embeded documents OR values SEPARATED BY COMMA>]}}})
      • for adding more than one values or embeded documents to the array
    • db.<collection>.updateOne({<field1>:<value1>}, {$push: {<array field>: {$each: [<embeded documents OR values SEPARATED BY COMMA>], $sort: {<subfield>: <1 OR -1>}, $slice: <n>}}})
      • sort sorts entire array before storing (optional)
      • slice takes the first n values/embeded documents and stores (optional)
  14. Removing embeded document or value from an array
    • db.<collection>.updateOne({<field1>:<value1>}, {$pull: {<array field>: {<subfield>: <value>}}})
      • removes matching documents/values from array
    • db.<collection>.updateOne({<field1>:<value1>}, {$pop: {<array field>: <1 for last element or -1 for first element>}}})
      • removes first or last item from the array
  15. $addToSet
    • db.<collection>.updateOne({<field1>:<value1>}, {$addToSet: {<array field>: <embeded document OR value>}})
      • for adding one value or embeded document to the array only once. If you try again it won't work since it adds only unique values. If duplicate, it won't execute
  16. .replaceOne()
    1. Used to replace entire document with a new document but retain the id

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