Remove a item in nested array

[Zuyang Kou]

I have a document like this:

{'arr': [['Bob', true], ['Alice', true], ['Mike', false]]}

I want to remove the item containing 'Bob', after operation the
document will become {'arr': [['Alice', true], ['Mike', false]]} .

How can I do this?

Or I should choose another scheme?

--
Code is poetry.

[Karl Seguin]

Use $pull:

http://www.mongodb.org/display/DOCS/Updating#Updating-%24pull

[Zuyang Kou]

I don't know how to use $pull in this case, I trid db.foo.update({}, {
$pull : {'arr': {'0': 'Bob'}}}) , but take no effect.

Could you give me the exact command I should use?

On Thu, Oct 13, 2011 at 10:47 PM, Karl Seguin <karls...@gmail.com> wrote:
> Use $pull:
> http://www.mongodb.org/display/DOCS/Updating#Updating-%24pull
>
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--
Code is poetry.

[Sam Millman]

It won't work on nested arrays.

The only way really atm is client side tbh.

[Karl Seguin]

ya, sorry..I didn't pay close enough attention to your structure..my bad.

[Brandon Diamond]

Hi Zuyang,

The best way forward is to change your schema such that you do not
have an array of arrays: instead, store a sub-document with two
fields, { "name": "Bob", "someNameForBool": true }.

Then, you can provide a matching expression so you can target sub-
documents by name. For example --

> db.stuff.save({ "arr": [ { "a": 1, "b": 2 }, { "a": 2, "b": 2 }, { "a": 3, "b": 1 } ] })
> db.stuff.update({}, { "$pull": { "arr": { "a": 2 } } })
> db.stuff.find()
{ "_id" : ObjectId("a0987e09ae70f987f"), "arr" : [ { "a" : 1, "b" :
2 }, { "a" : 3, "b" : 1 } ] }

Also, keep in mind that updates do not affect more than one document
by default. If more than one document will match your update selector,
you should pass in the multi-update flag.

Hope this helps,
- Brandon

On Oct 13, 11:10 am, Zuyang Kou <leaf...@gmail.com> wrote:
> I don't know how to use $pull in this case, I trid db.foo.update({}, {
> $pull : {'arr': {'0': 'Bob'}}}) , but take no effect.
>
> Could you give me the exact command I should use?
>