mongodb - 列出mongodb中某个字段的所有值

Question

如何获得一个数组，其中包含集合中所有文档的某个字段的所有值？

db.collection:

{ "_id" : ObjectId("51a7dc7b2cacf40b79990be6"), "x" : 1 }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be7"), "x" : 2 }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be8"), "x" : 3 }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be9"), "x" : 4 }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990bea"), "x" : 5 }

"db.collection.ListAllValuesForfield(x)" 结果:[1,2,3,4,5]

另外，如果这个字段是一个数组呢？

{ "_id" : ObjectId("51a7dc7b2cacf40b79990be6"), "y" : [1,2] }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be7"), "y" : [3,4] }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be8"), "y" : [5,6] }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990be9"), "y" : [1,2] }
{ "_id" : ObjectId("51a7dc7b2cacf40b79990bea"), "y" : [3,4] }

"db.collection.ListAllValuesInArrayField(y)" 结果:[1,2,3,4,5,6,1,2,3,4]

另外，我可以让这个数组独一无二吗？ [1,2,3,4,5,6]

Answer 1

db.collection.distinct('x')

应该为您提供该字段的唯一值数组。