How to iterate a mongo db document and update a nested array

Question

I need to remove entries inside a 2d array of documents structure in mongodb.

Sample is as below

{
    "_id" : ObjectId("5ffef283f1f06ff8524aa2c2"),
    "applicationName" : "TestApp",
    "pName" : "",
    "environments" : [],
    "stages" : [],
    "createdAt" : ISODate("2021-01-15T09:51:35.546Z"),
    "workflows" : [ 
        [ 
            {
                "pName" : "Test1",
                "wName" : "TestApp_Test1",
                "agent" : ""
            }, 
            {
                "pName" : "Test2",
                "wName" : "TestApp_Test2",
                "agent" : ""
            }
        ], 
        [ 
            {
                "pName" : "Test1",
                "wName" : "TestApp_Test1",
                "agent" : ""
            }
        ]
    ],
    "updatedAt" : Date(-62135596800000)
}

So, I want to remove all document occurences of

{
  "pName" : "Test1",
  "wName" : "TestApp_Test1",
  "agent" : ""
}

from both the arrays.

pName:Test1 can be used to filter it out.

What's the query which can be used to find this and delete it ?

I am ok to do a find and then iterate over the collection , find the matching entry and then update the document. I have to do this using Go mongodb driver

Since this is kind of complex for me as I am new to both golang and mongo db, I am stuck.

Update: 1.Tried {$pull: {workflows: {pName:"Test1"}}}, {multi: true} in the update() call as suggested but didn't work.

2.Tried something like this

db.getCollection('workflows').update({_id:ObjectId('5ffef283f1f06ff8524aa2c2')}, {$pull:{workflows: { $elemMatch: {pName:'Test2'}}}} )

This is removing the entire array as shown below because Test2 is present in that. I need to remove only the Test2 document

[ 
    {
        "pName" : "Test1",
        "wName" : "TestApp_Test1",
        "agent" : ""
    }, 
    {
        "pName" : "Test2",
        "wName" : "TestApp_Test2",
        "agent" : ""
    }
]

Gibbs · Accepted Answer · 2021-01-15 17:02:18Z

1

I'll give you a hint as you are new and you haven't posted the tried things.

You could use $pull to remove documents matching the conditions.

similar example

And you could use official mongodb driver for go or most used gopkg

An example SO post

edited Jan 15, 2021 at 17:02

answered Jan 15, 2021 at 16:56

Gibbs

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2 Comments

Abbas Over a year ago

Thanks. I tried {$pull: {workflows: {pName:"Test1"}}}, {multi: true} in the update() call. It said it updated in the mongo client but it didn't remove the entry. I know this needs a modification since its another enclosing array. How do we do it in this case ?

Gibbs Over a year ago

Alternatively, you can iterate by simple find and update workflows after removing programmatically.

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