Stage 2 · Lesson 2 of 9
find, findOne and equality filters
find(filter) returns every document that matches the filter, and findOne(filter) returns the first match or . A filter is itself a document: { status: "shipped", country: "PK" } matches documents where both are equal to those values, so listing several fields means AND.
An empty filter, {}, matches everything. Matching is exact and case sensitive, and type matters: the string "5" does not equal the number 5. A filter on a field that some documents lack simply skips them.
countDocuments(filter) counts matches without fetching them. Filtering on the server rather than in your code means only the matching documents travel over the network, and can help later.
Common trapfiltering in application code after find({}) returns the whole collection.
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Free: the CRUD lessons on inserting, finding, replacing, updating and deleting documents, with labs