3.分頁處理-Node部分

這邊把分頁所需要的變數算出來 主要是

• items(頁數)
• currentpage(目前頁數)
• next(下一頁)
• prev(上一頁)
• total(總筆數)
• limit(每頁的資料筆數) 這裡是用bookshelf寫的，mongodb其實也是要算這些東西。 存在pagination傳回client。

  generatePagination: function (totalRecords) {
    var self = this;
    var totalpages = Math.ceil(totalRecords / self.limit);
    var groups = Math.ceil(totalpages / self.paginationLimit);
    var currentpage = self.currentpage;
    var items = [];
    var lastpage = totalpages;
    var next = currentpage < lastpage ? currentpage + 1 : 1;
    var prev = currentpage < 2 ? lastpage : currentpage - 1;
    var isFirstPage = currentpage === 1;
    var isLastPage = currentpage === lastpage;
    var highestF = currentpage + 2;
    var lowestF = currentpage - 2;
    var counterLimit = totalpages - 2;
    if (groups > 1) {
      items.push(1);
      items.push(2);
      // if our current page is higher than 3
      if (lowestF > 3) {
        items.push('...');
        //lets check if we our current page is towards the end
        if (lastpage - currentpage < 2) {
           lowestF -=  3; // add more previous links
        }
      }
      else {
        lowestF = 3; // lowest num to start looping from
      }
      for (var counter = lowestF; counter < lowestF + 5; counter++) {
        if (counter > counterLimit) {
          break;
        }
        items.push(counter);
      }
      // if current page not towards the end
      if (highestF < totalpages - 2) {
        items.push('...');
      }
      items.push(lastpage - 1);
      items.push(lastpage);
    }
    else {
      // no complex pagination required
      for (var counter2 = 1; counter2 <= lastpage; counter2++) {
        items.push(counter2);
      }
    }
    self.pagination = {
      items: items,
      currentpage: currentpage,
      base: self.base,
      isFirstPage: isFirstPage,
      isLastPage: isLastPage,
      next: next,
      prev: prev,
      total: totalRecords,
      limit: self.limit
    };
    return self.pagination;
  }