Using MongoDB $set to update multiple subdocuments - mongodb

Question

I have such Article-documents:
{
"_id" : "rNiwdR8tFwbTdr2oX",
"createdAt" : ISODate("2018-08-25T12:23:25.797Z"),
"title" : "Happy",
"lines" : [
{
"id" : "5efa6ad451048a0a1807916c",
"text" : "Test 1",
"align" : "left",
"indent" : 0
},
{
"id" : "ae644f39553d46f85c6e1be9",
"text" : "Test 2"
},
{
"id" : "829f874878dfd0b47e9441c2",
"text" : "Test 3"
},
{
"id" : "d0a46ef175351ae1dec70b9a",
"text" : "Test 4"
},
{
"id" : "9bbc8c8d01bc7029220bed3f",
"text" : "Test 5"
},
{
"id" : "6b5c02996a830f807e4d8e35",
"text" : "Test 6",
"indent" : 0
}
]
}
I need to update some Lines.
For example I have array with ids of the line which must be updated.
let lineIds = [
"5efa6ad451048a0a1807916c",
"829f874878dfd0b47e9441c2",
"6b5c02996a830f807e4d8e35"
];
So I try to update attributes "attr" for the "lines" and I do following:
'articles.updateLines': function (articleId, lineIds, attr, value) {
return Articles.update({
'_id': articleId,
'lines.id': { $in: lineIds }
},
{
$set: {
['lines.$.' + attr]: value
}
},
{ multi: true }
);
}
The problem is that just the first line (with id="5efa6ad451048a0a1807916c") is updated.
Any ideas? Thanks! :)

Answer 1

You can use $[]. This will works only MongoDB version 3.6 and above.
Refer link :
https://docs.mongodb.com/manual/reference/operator/update/positional-all/
You can also see this stackoverflow question reference:
How to add new key value or change the key's value inside a nested array in MongoDB?
You can convert below query in your function
db.col.update(
{ '_id':"rNiwdR8tFwbTdr2oX", },
{ $set: { "lines.$[elem].text" : "hello" } },
{ arrayFilters: [ { "elem.id": { $in: lineIds } } ],
multi: true
})

Answer 2

'lines.id': { $in: lineIds }
This won't work, because lines is an array.
What I understand from your question, you can prepare a new array with proper processing and replace the lines array with the new one. Here is an idea how to do this:
'articles.updateLines': function (articleId, lineIds, attr, value) {
let lines = Articles.findOne(articleId).lines;
// prepare a new array with right elements
let newArray = [];
for(let i=0; i<lines.length; i++){
if(lineIds.includes(lines[i].id)){
newArray.push(value)
}
else newArray.push(lines[i])
}
return Articles.update({
'_id': articleId,
},
{
$set: {
lines: newArray
}
}
);
}