Mongo alias set-CodePudding

Mongo data in the database

 {
"_id" : ObjectId (" 5 c88c7d72db68f5597065063 "), 
"Array" : [
{
"A" : "a1", 
"B" : {
"C" : "c1" 
} 
}, 
{
"A" : "a2", 
"B" : {
"C" : "c2" 
} 
} 
] 
}

I want to take out from the mongo data format for (remove the b this layer) :

 {
"_id" : ObjectId (" 5 c88c7d72db68f5597065063 "), 
"Array" : [
{
"A" : "a1", 
"C" : "c1" 
}, 
{
"A" : "a2", 
"C" : "c2" 
} 
] 
}

I use the query:

 the test_alias. Aggregate ({" $project ": {" array. A" : 1, "array. C" : "$array. The biggest"}})

Results:

 {
"_id" : ObjectId (" 5 c88c7d72db68f5597065063 "), 
"Array" : [
{
"A" : "a1", 
"C" : [
"C1", 
"C2" 
] 
}, 
{
"A" : "a2", 
"C" : [
"C1", 
"C2" 
] 
} 
] 
}

Such as how to get, please I hope the data format