How to rename fields in MongoDB output?

Question

I am new to MongoDB, my native language is Spanish. So I'm not sure how to find what I need.

I will try to make myself understandable.

I do this query and the result is an array.

For example :

Users.find({passport:123, (err, result) => {
   //output of result
   [ 
     {"nombre":"pedro","apellido":"jose"},
     {"nombre":"pablo","apellido":"jacinto"},
     {"nombre":"jose","apellido":"berta"},
   ]

I want to know if there is a more effective way to do something so that using some function from mongodb I can customize the output to avoid doing something like this:

Required Output :

   [ 
     {"name":"pedro","lastname":"jose"},
     {"name":"pablo","lastname":"jacinto"},
     {"name":"jose","lastname":"berta"},
   ]

is there any way to process the output information directly from mongoDB?

So do you wanted to nombre convert to name & apellido to lastname ? If yes there is no such thing that does directly, but you can write query to map nombre to name.. — whoami - fakeFaceTrueSoul
– whoami - fakeFaceTrueSoul, Commented Mar 24, 2020 at 3:48
result.map((element)=>{ return {name:element.nombre,lastname:element.apellido} } ? — yavg
– yavg, Commented Mar 24, 2020 at 3:50

whoami - fakeFaceTrueSoul · Accepted Answer · 2020-03-24 04:00:34Z

2

You need to use MongoDB's Aggregation to do that :

db.collection.aggregate([
  /** Filter docs based on criteria */
  {
    $match: {
      passport: 123
    }
  },
  /** Transform fields into required form */
  {
    $project: {
      name: "$nombre",
      lastname: "$apellido"
    }
  }
])

Test : MongoDB-Playground

Ref : $match , $project

edited Mar 24, 2020 at 4:00

answered Mar 24, 2020 at 3:55

whoami - fakeFaceTrueSoul

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8 Comments

yavg Over a year ago

I am using mongoose, I am too new, in this .. how can I get the result? a callback does not work Transaccion.aggregate([{...}], (err, value) => {})

whoami - fakeFaceTrueSoul Over a year ago

@yavg : callbacks should work, are you seeing any error ? Check this in case if you think callbacks don't work :: (stackoverflow.com/questions/23805772/…)

yavg Over a year ago

I am getting this error: i.imgur.com/UH13l1C.jpg , can you please tell me how to correct it. I do not understand and excuse my ignorance.

whoami - fakeFaceTrueSoul Over a year ago

@yavg : As error says you should pass all stages in an array like :: .aggregate([{},{}]) but not like :: .aggregate({},{})

whoami - fakeFaceTrueSoul Over a year ago

@yavg : It seems ok, is that throwing an issue ?

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