One to many relationship mongoose.

[0san0]

mongodb version v3.6.0
npm version 5.6.0
node version v8.9.3

I have used two schema blog and its comment.where it has a unidirectional relationship between blogs and comments (1 to Many).

const BlogPostSchema = mongoose.Schema({
  Title: { type: String },
  Description: { type: String },
  Image: { type: String }
});

const CommentSchema = mongoose.Schema({
  // object reference from BlogPost
  BlogPost  : { type: mongoose.Schema.Types.ObjectId, ref: 'BlogPost' },
  Image: { type: String }
  Message: { type: String }
});

var comment = Comment.find().populate('BlogPost').exec();

Using this query, I am able to fetch all comments with its blog.

[
    {
        "_id": "5a45d53f4c02c537427a52a7",
        "Message": "This is my test first comment.",
        "BlogPost": {
            "_id": "5a45d4f35193c636b3c1b673",
            "Description": "This is blog description.",
            "Title": "This is my blog."
            "Image": "36a3d5e0.jpg",
        },
       "Image": "66a3d5e0.jpg",
        "__v": 0
    },
    {
        "_id": "5a45d5794c02c537427a52a8",
        "Message": "This is my test second comment.",
        "BlogPost": {
            "_id": "5a45d4f35193c636b3c1b673",
            "Description": "This is blog description.",
            "Title": "This is my blog."
            "Image": "36a3a5e0.jpg",
        },
        "Image": "66a3d5e1.jpg",
        "__v": 0
    },
]

which is working fine.
1.How would I fetch all blogs with its comment with this unidirectional (reverse) one to many relationships?
2.How would I change "Image": "66a3d2f1.jpg" to "Image": "https://www.example.com/uploads/66a3d2f1.jpg" value?
Expected result.

[
    {
        "_id": "5a45d4f35193c636b3c1b673",
        "Description": "This is blog description.",
        "Title": "This is my blog.",
        "Image": "66a3d2f1.jpg",
        "__v": 0,
        "Comments": [
            {
                "_id": "5a45d53f4c02c537427a52a7",
                "Message": "This is my test first comment.",
                "BlogPost": "5a45d4f35193c636b3c1b673",
                "Image": "66a3d5q1.jpg",
                "__v": 0
            },
            {
                "_id": "5a45d5794c02c537427a52a8",
                "Message": "This is my test second comment.",
                "BlogPost": "5a45d4f35193c636b3c1b673",
                "Image": "66a3d5f3.jpg",
                "__v": 0
            },
            {
                "_id": "5a45ebe562509738a12c3eb5",
                "Message": "This is my test second comment.",
                "BlogPost": "5a45d4f35193c636b3c1b673",
                "Image": "66a3d5f1.jpg",
                "__v": 0
            }
        ]
    },
    {
        "_id": "5a45d5c54c02c537427a52a9",
        "Description": "This is blog description.",
        "Title": "This is my blog.",
        "Image": "66a3e5f1.jpg",
        "__v": 0,
        "Comments": [
            {
                "_id": "5a45ebec62509738a12c3eb6",
                "Message": "This is my test second comment.",
                "BlogPost": "5a45d5c54c02c537427a52a9",
                "Image": "66a3d5e0.jpg",
                "__v": 0
            },
            {
                "_id": "5a4d05dcfe3557278310e6ac",
                "Message": "This is my test second comment.",
                "BlogPost": "5a45d5c54c02c537427a52a9",
                "Image": "66a3d5e1.jpg",
                "__v": 0
            }
        ]
    }
]

[sobafuchs]

1. you can use a virtual populate: read this blog post for more info on how to use this API: http://thecodebarbarian.com/mongoose-virtual-populate

2. I'm not sure I understand the question. Can't you just query for it in the database based on that Image property and update it?

[0san0]

This is the response, I have got.

[
    {
        "_id": "5a45d4f35193c636b3c1b673",
        "Description": "This is blog description.",
        "Title": "This is my blog.",
        "Image": "66a3d2f1.jpg",
        "__v": 0,
        "Comments": [
            {
                "_id": "5a45d53f4c02c537427a52a7",
                "Message": "This is my test first comment.",
                "BlogPost": "5a45d4f35193c636b3c1b673",
                "Image": "66a3d5q1.jpg",
                "__v": 0
            }
        ]
    }
]

I mean how would i modify json response that i am getting through populating model?
But the expected response is below.

[
    {
        "_id": "5a45d4f35193c636b3c1b673",
        "Description": "This is blog description.",
        "Title": "This is my blog.",
        "Image": "https://www.example.com/uploads/66a3d2f1.jpg",
        "__v": 0,
        "Comments": [
            {
                "_id": "5a45d53f4c02c537427a52a7",
                "Message": "This is my test first comment.",
                "BlogPost": "5a45d4f35193c636b3c1b673",
                "Image": "https://www.example.com/uploads/66a3d5q1.jpg",
                "__v": 0
            }
        ]
    }
]

[sobafuchs]

I'm sorry I still don't understand. What do you want to change in the response / why can't you do it with javascript?