Projection
find(), ka, SECOND, ARGUMENT, PROJECTION, hai — 1, wale, FIELDS, INCLUDE, hote, hain, 0, wale, EXCLUDE. INCLUDE, aur, EXCLUDE, (SIVAY, _id, ke) EK, HI, QUERY, mein, MIX, NAHI, kiye, ja, sakte.
Projection, PERFORMANCE, ke, liye, IMPORTANT, hai — SIRF, ZAROORI, FIELDS, RETURN, karne, se, NETWORK, TRANSFER, aur, CLIENT-SIDE, PROCESSING, kam, hoti hai, ESPECIALLY, LARGE, DOCUMENTS, ke, liye.
// Sirf name aur email fields (aur _id, default):
db.users.find({}, { name: 1, email: 1 });
// _id ko, bhi, EXCLUDE karna:
db.users.find({}, { name: 1, email: 1, _id: 0 });
// Password field, EXCLUDE karna:
db.users.find({}, { password: 0 });- Projection = find() ka second argument — kaun se fields return honge
- 1 = include, 0 = exclude — dono, ek, saath, mix, (sivay, _id ke), nahi, ho, sakte
- Sensitive fields, (password) exclude, karne, ke, liye, ZAROORI, hai
Dot, notation, se, nested, fields, ki, projection, ki, ja, sakti, hai — jaise, "address.city": 1, sirf, address, object, ke, andar, se, city, field, return, karega, poora, address, object, nahi.
db.users.find({}, { name: 1, "address.city": 1 });$slice, operator, se, EK, array, field, ke, SIRF, KUCH, elements, return, kiye, ja, sakte, hain — jaise, EK, comments, array, mein, se, sirf, RECENT, 5, comments, chahiye, POORA, array, nahi.