How to repeat all fields key and set the new value in $project stage in aggregate mongodb?

Question

I have a schema model with so many fields like below example, I want to clone root field in suggest_foo to $project stage of aggregation without having to manually rewrite those fields and then set those fields with new value as my logic.

Example:

• schema model:

  const fooSchema = new Schema({
     suggest_foo: 
       foo1: String,
       foo2: String,
       foo3: String,
       foo4: String,
       foo5: String,
     }
     ...
  })
  

• seeds data:

  {
     suggest_foo: {
       foo1: 'Foo1',
       foo2: 'Foo2',
       foo3: 'Foo3',
       foo4: 'Foo4',
       foo5: 'Foo5',
     }
  }
  

• aggregate query code:

  fooSchema.aggregate([
     ...
     {
       $project: {
          // I want to clone root in suggest_foo (eg: foo1, foo2, foo(n)...) to be here.
       }
     }
  ])
  

My output result that I expected look like:

  {
     foo1: 'Foo1 maybe you like',
     foo2: 'Foo2 maybe you like',
     foo3: 'Foo3 maybe you like',
     foo4: 'Foo4 maybe you like',
     foo5: 'Foo5 maybe you like',
  }

Answer 1

One option is to use $replaceRoot with $arrayToObject and $objectToArray as this will allow you to manipulate array in a loop:

db.collection.aggregate([
  {$replaceRoot: {
      newRoot: {
        $arrayToObject: {
          $map: {
            input: {$objectToArray: "$suggest_foo"},
            in: {
              v: {$concat: ["$$this.v", " maybe you like"]},
              k: "$$this.k"
            }
          }
        }
      }
  }}
])

See how it works on the playground example