I am new to mongo so excuse me if it's a noobish question. I have wrongfully updated a specific flag in mongo with "true"/"false" (type strings). I want a query so that I could update my collection and change the type of the flag from string "true" to boolean true.
Example:
{flag: "true"} to { flag : true}
So I have 2 questions:
For relatively small collections, perform an update if the type of field is string:
db.collection.find({ "flag": { $type : 2 } }).forEach(function (doc){
var isTrueSet = (doc.flag === "true");
doc.flag = isTrueSet; // convert field to Boolean
db.collection.save(doc);
});
For medium/large collections you can use the bulkWrite API as
var cursor = db.collection.find({ "flag": { "$exists": true, "$type": 2 } }),
ops = [];
cursor.forEach(function(doc){
var isTrueSet = (doc.flag === "true");
ops.push({
"updateOne": {
"filter": { "_id": doc._id },
"update": { "$set": { "flag": isTrueSet } }
}
});
if (ops.length == 1000) {
db.collection.bulkWrite(ops);
ops = [];
}
});
if (ops.length > 0) { db.collection.bulkWrite(ops); }
Just call these two queries:
db.coll.update({
flag: "true"
}, {
$set: {flag: true}
}, { multi: true })
db.coll.update({
flag: "false"
}, {
$set: {flag: false}
}, { multi: true })
First one changes all "true" to true, second you will get it.
For a medium/big collection this will work significantly faster than already suggested foreach statement.
See MongoDB Manual - Modify Documents. Example:
db.collectionName.update({_id: "yourid"}, {$set: {flag : true}})
Strings can be converted to boolean in MongoDB v4.0 using $toBool operator. In this case
db.col.aggregate([
{
$project: {
_id: 0,
flagBool: { $toBool: "$flag" }
}
}
])
Outputs:
{ "flagBool" : true }
