Append a string to the end of an existing field in MongoDB

Question

I have a document with a field containing a very long string. I need to concatenate another string to the end of the string already contained in the field.

The way I

Answer 1

this is a sample of one document i have :

{
    "_id" : 1,
    "s" : 1,
    "ser" : 2,
    "p" : "9919871172",
    "d" : ISODate("2018-05-30T05:00:38.057Z"),
    "per" : "10"
}

to append a string to any feild you can run a forEach loop throught all documents and then update desired field:

db.getCollection('jafar').find({}).forEach(function(el){
    db.getCollection('jafar').update(
        {p:el.p},
        {$set:{p:'98'+el.p}})    
    })