I want to push some values into array using Python.
Maybe next time when i update the array ,it will insert some values exists ,so it will got some duplicate values.
I want to know is there anyway to avoid duplicate values.
Should I use db.collection.find() to determine whether I should insert or not ?
db.graph.insert_one({"user_id": a.url}, )
for j in a.followers:
db.graph.update({"user_id": a.url}, {"$push": {"following": j.url}})
The best way to do this is using $addToSet operator which ensures that there are no duplicate items added to the set and the $each modifier to add multiple values to the"following" array.
urls = [j.url for j in a.followers]
db.graph.update_one({"user_id": a.url}, {"$addToSet": {"following": {"$each": urls}}})
also you should use the update_one method because update is deprecated.
I think, that you can use $addToSet operator: https://docs.mongodb.org/manual/reference/operator/update/addToSet/
I'm lazy ass, so I'm going to paste here the code i use. Don't mind the language. The underline logic is similar.
// array of object prevent duplication 1------------------------------
Dict_target_schema.index(
{ user_id: 1, wid: 1, w: 1, "exp.r_id": 1 },
{ unique: true }
);
let result = await Dict_target.findOneAndUpdate(
{ user_id, wid, w, "exp.r_id": { $ne: article_id } },
{
$push: {
exp: {
r_id: article_id,
},
},
},
{
upsert: true,
new: true,
}
);
// array of object prevent duplication 2-----------------
Dict_target_schema.index(
{ user_id: 1, wid: 1, w: 1 },
{ unique: true }
);
let result = await Dict_target.findOneAndUpdate(
{
user_id,
wid,
w,
exp: { $not: { $elemMatch: { r_id: article_id } } },
},
{
$push: {
exp: {
r_id: article_id,
},
},
},
{
upsert: true,
new: true,
}
);
