Updating a nested array object in Mongo db

Question

This is the json object

{
"account_id":"1",
"sections":[ {
 "section_name":"abc",
 "labels": [{
 "name": "label1",
 "value": "value1"
 },
 {
 "name": "label2",
 "value": "value2"
 }]
 },
 {
 "section_name":"def",
 "labels": [{
 "name": "label3",
 "value": "value3"
 }]
 }]
}

In this json object I wanted to change the value of label3 from value3 to value4 in the section def. There are different accounts but I have listed only one json object here.

I have used the below code, but it didn't work for me. Here I have passed section name(section), label name (label) and label value (value).

let query = {
account_id: event.accountId.toString(),
sections: {
 section_name: section,
 labels: {
 label_name: label
 }
 }
 };
 return using(connectDatabase(), db => {
 return db.collection(TABLE_NAME).updateOne(query, { $set: { 
 'sections.$.labels.$.value': value } });
 }).then(
 result => {
 cb(null, responseObj(result, 200));
 },
 err => {
 cb(responseObj(err, 500));
 }
 );

Can someone help me ? Thanks in advance

• Naga Sai A: any errors while running that query?
• Uthpala Pitawela: Its not updating in the database.
• Naga Sai A: posted answer using arrayFilters, hope it works for you

Answer 1

To achieve expected result, use below option of using arrayFilters for nested objects

• Get main Object using account_id
• Using ArrayFiter $[identfier].section : "def" and $[identfier].name: "label3"

---

 db.collection(TABLE_NAME).updateOne({
 account_id: event.accountId.toString(),
 {
 "$set": {
 "sections.$[elem].labels.$[label].value": value
 }
 },
 {
 "arrayFilters": [{
 "elem.section_name": section
 }, {
 "label.name": label
 }]
 }
})

Please refer this link for more details - https://docs.mongodb.com/manual/reference/operator/update/positional-filtered/

Another example of arrayFilters with example - How to Update Multiple Array Elements in mongodb

• Uthpala Pitawela: "Unsupported projection option: $set: { sections.$[elem].labels.$[label].value: \"valllll\" }", <----- got this error
• Uthpala Pitawela: I have checked this in RoboMongo . Will that affect for this error?
• Naga Sai A: @UthpalaPitawela, should enclose this quotes - sections.$[elem].labels.$[label].value
• Uthpala Pitawela: I think the probelm is the MOngo version where this works only for versions higher 3.6 while my mongo version is less than 3.6
• Naga Sai A: oh k @UthpalaPitawela :) , Did you try to upgrade to 3.6 or are you trying for solution for version less than 3.6?

Answer 2

Updated Query You can use this query

db.testcol.update(
 { },
 { $set: { "sections.$[element].labels.$[element1].value" : "value1New" } },
 { multi: true,
 arrayFilters: [ { "element.section_name": { $eq: "abc" } }, { "element1.name": { $eq: "label1" } }]
 }
)

You can check the following query: Where 1 is the index value of the array.

db.testcol.update(
 {
 account_id:"1", 
 "sections.section_name":"def"
 }, 
 {
 $set:{
 "sections.1.labels.1.value":"value8"
 }
 }
) 

If you want to update all the values then you can use:

db.testcol.update(
{
 account_id:"1", 
 "sections.section_name":"def"
}, 
{
 $set:{
 "sections.$[].labels.$[].value":"value8"
 }
}

)

Please check and let me know if it is help-full.

• Uthpala Pitawela: This does not work as sections.1.labels.1.value":"value8 , updates index 1 and sometimes the intended label not always in the index 0.