paginate

paginate(rel, {<sort attr>}, page_size, {<attr list>}) paginate(rel, {<sort attr>}, page_size, {<attr list>}, prev, next) paginate(rel, {<sort attr>}, page_size, {<attr list>}, prev, next, options)

Converts rel into an ordered table with a specified left-right attr list, starting from an optional prev/next key and in blocks of a given page_size.

Returns a tuple{data:table{...}, prev_page:str, next_page:str} where data is the next page of data and prev_page and next_page are key positions for adjacent pages that can be passed into subsequent paginate calls.

The {sort attr} should be unique and in the attr list, and will be used to order the tuples. Use -attr to reverse the sort. The default sort attribute name is '_sort', if left empty.

page_size will be used to limit the number of tuples in the table (after the ordering and any prev/next jump).

prev/next are each {v:str}. If they are passed in, they indicate where the data should start from. Generally you should pass in values returned from earlier calls of paginate.

An example prev/next value is: {v:str}{["SNO:str=S2"]} Values can arrive via http.hh form, via URL query/post: form[k="p"], form[k="n"]

A table is an array of tuples and can no longer be used in relational expressions.

Examples

Note: the data attribute of these results are no longer relations. They are tables, i.e. ordered sets of tuples.

first page

print(paginate($P, {PNO}, 3, {PNO,PNAME,COLOR,WEIGHT,CITY}))

┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄
  data                                        prev_page   next_page   
  #########################################               PNO:str=P3  
    PNO   PNAME   COLOR   WEIGHT   CITY                               
    P1    Nut     Red         12   London                             
    P2    Bolt    Green       17   Paris                              
    P3    Screw   Blue        17   Rome                               
  #########################################                           
┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄

Note: the next_page can be used to fetch the next page by passing it to paginate as the next parameter, e.g. when a user clicks a "next page" button.

There is no prev_page here which means there is no earlier page available.

page after first page

Here we pass a next_page value (from the previous example) which specifies where the page should start from, i.e. the next page after the previous example, in this case

print(paginate($P, {PNO}, 3, {PNO,PNAME,COLOR,WEIGHT,CITY}, {v:str}{}, {v:str}{["PNO:str=P3"]}))

┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄
  data                                        prev_page    next_page  
  #########################################   PNO:str=P4              
    PNO   PNAME   COLOR   WEIGHT   CITY                               
    P4    Screw   Red         14   London                             
    P5    Cam     Blue        12   Paris                              
    P6    Cog     Red         19   London                             
  #########################################                           
┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄

Note: the prev_page can be used to fetch the previous page by passing it to paginate as the prev parameter, e.g. when a user clicks a "previous page" button.

There is no next_page here which means there is no later page available.