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I am developing a web app using Codeigniter and MongoDB. The users can upload files and other users can comment on them.
I store the comments in an array called comments in the main file document. This is all fine but how can I remove specific comments from the array?
I cannot use ID as key since a user can add multiple comments. How would you recommend that I can do it?
This is my comment array:
"comments": [ { "user_id": ObjectId("4f240b433dc7937d68030000"), "user_name": "james", "user_comment": "This is a comment", "created_at": "2012-01-2821: 20: 44" }, { "user_id": ObjectId("4f240b433dc7937d68030000"), "user_name": "mandy", "user_comment": "This is another comment", "created_at": "2012-01-2821: 31: 07" } ], 
924
pop() function: This method is use to remove elements from the end of an array. shift() function: This method is use to remove elements from the start of an array. splice() function: This method is use to remove elements from the specific index of an array.
Find the index of the array element you want to remove using indexOf , and then remove that index with splice . The splice() method changes the contents of an array by removing existing elements and/or adding new elements. The second parameter of splice is the number of elements to remove.
If you can identify the comment item by matching userid, name or comment -- then you can remove that comment using update() command with $pull modifier along with the appropriate condition.
If you cannot do as above, include an unique id in the comments (like UUID).
To delete the comment, do the following:
db.coll.update({<cond to identify document}, {$pull: {'comments': {'name': <name>}}} ) If you use the id, which is preferred:
db.coll.update({<cond to identify document}, {$pull: {'comments': {'id': <id>}}} ) maybe you can remove comment by its 'created_at' time, as the time is unique.
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