Update Documents From Each Value of an Input Array - mongodb

Question

I have a JSON with two keys: id and name. I need a way to insert that id on my collection (querys.project.name) when the name on it and on the JSON matches.
Example of my JSON:
var projectsMysql = [
{
"id" : 1,
"name" : "Something"
},
{
"id" : 5,
"name" : "Something else"
},
{
"id" : 50,
"name" : "Some name"
}]
and in my collection about 60 documents like this one:
{
"_id" : ObjectId("58e42bf30a34d641be6c25c2"),
"folio" : "R-666-69",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Something else"
// "projectsMysql_id" : 5 THIS SHOULD BE PLACED HERE
},
}
I wrote a function for Node.js but now I need to run this directly on the mongo shell, I read that I need to use cursor.forEach() method but I couldn't find a way to do it, this is my function:
projectsMysql
.forEach(function(project){
var query = {
name: project.name
}
db.getCollection('requests')
.find(query)
.exec(function(err, response){
if (err) {
return
}
if (response) {
db.getCollection('requests')
.update({id: response.id}, {$set: {
'project.projectsMysql_id': project.id
console.log("element inserted");
}})
.exec(function(err){
});
}
});
});
Can you point me in to the right direction?

Answer 1

What you want here is bulkWrite(), where instead of actually executing an update() for each document within the projectsMysql array you actually just construct a "single" statement made of "multiple" updates which sends to the server and updates the appropriate documents:
db.getCollection('requests').bulkWrite(
projectsMysql.map(({ id, name }) =>
({ "updateOne": {
"filter": { "project.name": name },
"update": { "$set": { "project.id": id } }
}})
)
)
If you expect "multiple documents" to match the condition, then simply switch to updateMany:
db.getCollection('requests').bulkWrite(
projectsMysql.map(({ id, name }) =>
({ "updateMany": {
"filter": { "project.name": name },
"update": { "$set": { "project.id": id } }
}})
)
)
Your array is already in memory so there is not really any point to doing any other kind of "iteration" and you can simply .map() the properties onto the updateOne statements ( or updateMany ) and issue them all in one statement. Updates are only actually processed where there is a "match" and indeed where there is something to actually update, as existing values will be left alone using $set.
To Demonstrate, considering these documents:
{
"folio" : "R-666-69",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Something else"
}
},
{
"folio" : "R-666-67",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Some name"
}
},
{
"folio" : "R-666-68",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Some name"
}
}
{
"folio" : "R-666-64",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Something"
}
},
{
"folio" : "R-666-65",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Different"
}
}
The the following update:
var projectsMysql = [
{
"id" : 1,
"name" : "Something"
},
{
"id" : 5,
"name" : "Something else"
},
{
"id" : 50,
"name" : "Some name"
}]
db.getCollection('requests').bulkWrite(
projectsMysql.map(({ id, name }) =>
({ "updateMany": {
"filter": { "project.name": name },
"update": { "$set": { "project.id": id } }
}})
)
)
Returns the response:
{
"acknowledged" : true,
"deletedCount" : 0,
"insertedCount" : 0,
"matchedCount" : 4,
"upsertedCount" : 0,
"insertedIds" : {
},
"upsertedIds" : {
}
}
And alters the matched documents accordingly:
{
"_id" : ObjectId("5b206a48f7fa0c655d90157a"),
"folio" : "R-666-69",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Something else",
"id" : 5
}
}
{
"_id" : ObjectId("5b206a48f7fa0c655d90157b"),
"folio" : "R-666-67",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Some name",
"id" : 50
}
}
{
"_id" : ObjectId("5b206a48f7fa0c655d90157c"),
"folio" : "R-666-68",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Some name",
"id" : 50
}
}
{
"_id" : ObjectId("5b206a48f7fa0c655d90157d"),
"folio" : "R-666-64",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Something",
"id" : 1
}
}
{
"_id" : ObjectId("5b206a48f7fa0c655d90157e"),
"folio" : "R-666-65",
"alias_purchase" : "Deal",
"project" : {
"description" : "",
"name" : "Different"
}
}