Limit API response to specific asset sub fields in collection

Support
1

How can I limit the fields displayed in the API response for assets?

fetch('/api/collections/get/posts?token=xxtokenxx', {
    method: 'post',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
        filter: {published:true},
        fields: {
                fieldA: 1, //what if this field is an asset field? 
                           //How can i specify the returned fields?
                           //I tried this with no success
                fieldA: {
                        fields:{fieldA1:1, fieldA2:0}
                },
                fieldB: 1
        },
        limit: 10
    })
})

this is what the API returns for asset field:

"FieldA":{
    "path":"..\/..",
    "title":"ext-1.jpeg",
    "mime":"image\/jpeg",
    "description":"",
    "tags":[],
    "size":22890,
    "image":true,
    "video":false,
    "audio":false,
    "archive":false,
    "document":false,
    "code":false,
    "created":1562254299,
    "modified":1562254299,
    "_by":"43657768878999",
    "width":573,
    "height":308,
    "colors":[
        "#cfbfae",
        "#0b0b0b",
        "#6b5d4e",
        "#848481",
        "#586e90"
    ],
    "folder":"",
    "_id":"5d1e1bdb33663653247643"
}

and I only need an API response like this:

    "FieldA":{
        "path":"..\/..",
        "title":"ext-1.jpeg",
        "_id":"5d1e1bdb33663653247643"
    }
2

if you use MongoDB as data storage then you should be able to do a query like this:


fetch('/api/collections/get/posts?token=xxtokenxx', {
    method: 'post',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
        filter: {published:true},
        fields: {
                'FieldA.path': 1,
                'FieldA.title': 1,
                'FieldA._id': 1,
                fieldB: 1
        },
        limit: 10
    })
})
3

Thanks for helping.
I am using the SQLight.
Any chance with this database for a similar sollution?