paginate

[aliabdolazimi]

hi.i have datas with this structrue { _id:"",parentId:"", ... } and i want to get datas with same paranetId using paginate.
for example the first elemnents that i show in client be objects with parentId:1 and it can includes one or more data matching db, and the seccond be objects with parentId:2 and ...
for example i may have 10 data in my db.3 of them have parentId : 1 two of them have parentId:2 and the rest have parentId:3
i set limit to 2 and i want to get the first two datas with same parent id.the first one is that 3 data i mentioned before with parentId:1 and the 2nd is two data with parentId:2. and when i scroll down load the rest data that has parentId:3 as the third elemnt.
i searched for it but i found nothing.
thanks a lot.