将布尔字段查询为“ not true”(例如，false 或不存在)

db.tests.find({deleted: {$ne: true}})

Where $ne stands for "not equal". (Documentation on mongodb operators)

JohnnyHK has the best answer. The $in selector is the shortest and cleanest IMO.

This will test for exactly "false" or "non existent". And can be indexed.

db.tests.find({$or:[{deleted:false},{deleted:{$exists:false}}]})

An example with a use of an index.

((function(){
print("creating collection 'testx' and inserting 50 trues, 50 falses, 50 non-existents");
db.testx.drop();
db.testx.ensureIndex({deleted:1});
for (var i=0;i<50;i++){
db.testx.insert({i:i,deleted:false});
};
for (var i=0;i<50;i++){
db.testx.insert({i:i,deleted:true});
};
for (var i=0;i<50;i++){
db.testx.insert({i:i});
};
var res0 = db.testx.find().explain();
var res1 = db.testx.find({deleted:false}).explain();
var res2 = db.testx.find({deleted:true}).explain();
var res3 = db.testx.find({deleted:{$exists:false}}).explain();
var res4 = db.testx.find({$or:[{deleted:false},{deleted:{$exists:false}}]}).explain();
var res5 = db.testx.find({$or:[{deleted:true},{deleted:{$exists:false}}]}).explain();
var res6 = db.testx.find({deleted:{$in:[false,null]}}).explain();
print("res0: all objects                      ("+res0["n"]+" found, "+res0["nscannedObjects"]+" scanned)");
print("res1: deleted is false                 ("+res1["n"]+" found, "+res1["nscannedObjects"]+" scanned)");
print("res2: deleted is true                  ("+res2["n"]+" found, "+res2["nscannedObjects"]+" scanned)");
print("res3: deleted is non-existent          ("+res3["n"]+" found, "+res3["nscannedObjects"]+" scanned)");
print("res4: deleted is false or non-existent ("+res4["n"]+" found, "+res4["nscannedObjects"]+" scanned)");
print("res5: deleted is true or non-existent  ("+res5["n"]+" found, "+res5["nscannedObjects"]+" scanned)");
print("res6: deleted is in [false,null]       ("+res5["n"]+" found, "+res5["nscannedObjects"]+" scanned)");
})())

This should print

creating collection 'testx' and inserting 50 trues, 50 falses, 50 non-existents
res0: all objects                      (150 found, 150 scanned)
res1: deleted is false                 (50 found, 50 scanned)
res2: deleted is true                  (50 found, 50 scanned)
res3: deleted is non-existent          (50 found, 50 scanned)
res4: deleted is false or non-existent (100 found, 100 scanned)
res5: deleted is true or non-existent  (100 found, 100 scanned)
res6: deleted is in [false,null]       (100 found, 100 scanned)

For the sake of completeness, another way to do this is with $in:

db.test.find({deleted: {$in: [null, false]}})

Including null in the array pulls in the docs where the deleted field is missing. This query can use an index on {deleted: 1} in the current 2.6.6 MongoDB release.

For the case that someone needs this in an aggregation pipeline instead of find, this is what worked for me

db.getCollection('tests').aggregate([
// ...previous operations...
{ $addFields: { "deleted_conclusion": { $cond: {
if:{ $ne: [ "$deleted", false ]}, then: { $cond: [ "$deleted", ":TRUE", ":FALSY"]}, else: ":FALSE"
}}}}
])

After adding the extra field you can go on with pipeline stages and have the information you miss

In case you are looking for mongoid syntax (I am using this in a rails app), this is what I came up with for a company's users:

2.3.1 :042 > accepted_consent = org.users.active.where(:accepted_terms_and_conditions => true).count
=> 553
2.3.1 :043 > not_accepted_yet = org.users.active.where(:accepted_terms_and_conditions.ne => true).count
=> 6331
2.3.1 :044 > 6331+553
=> 6884
2.3.1 :045 > org.users.active.count
=> 6884