db={product:[{"_id":ObjectId("6200a77598412e443c03f0ee"),"name":"1000","sku_code":"22","field_values":[{"field_id":ObjectId("61fd34cbbc787e45d256a270"),"key":"P4YZRK71CZAQ8IXJ3","value":"54"},{"field_id":ObjectId("61fb77b2384e2635f8a2d1ea"),"key":"SF_10KRUMSESSIONSPERMONTH","value":"34"}]}],field:[{"_id":ObjectId("61fb77b1384e2635f8a2d1e9"),"description":"sf_infrastructureFunction__c","is_read_only":false,"is_required":false,"name":"sf_infrastructureFunction","key":"SF_INFRASTRUCTUREFUNCTION","type":"number"},{"_id":ObjectId("61fb77b2384e2635f8a2d1ea"),"default":"123","description":"sf_10KRumSessionsPerMonth__c","is_read_only":false,"is_required":false,"name":"sf_10KRumSessionsPerMonth","key":"SF_10KRUMSESSIONSPERMONTH","type":"number"},{"_id":ObjectId("61fd34cbbc787e45d256a270"),"description":"UKXNVYBF7AXE1VOUH","is_read_only":false,"is_required":true,"name":"P4YZRK71CZAQ8IXJ3","key":"P4YZRK71CZAQ8IXJ3","type":"number"}]}

db.field.aggregate([{"$lookup":{"from":"product","localField":"_id","foreignField":"field_values.field_id","as":"field_data"}},{$unwind:{path:"$field_data",preserveNullAndEmptyArrays:true}},{"$addFields":{"field_data":{"$filter":{"input":"$field_data.field_values","as":"fv","cond":{$eq:["$$fv.field_id","$_id"]}}}}},{$addFields:{field_data:{$cond:{if:{$eq:["$field_data",null]},then:"$$REMOVE",else:"$field_data"}}}}])