我在morningstar的第一项工作，就是构建一个带分栏表头的grid表格。上面的表格中，第一行是父栏，第二行是子栏，第三行开始才是数据。而在table中还要实现这样的表头，还是有点麻烦的。
为了构建这种有父子栏的表头，我想到把表格头部的数据转化为按照table tr td的排列顺序，利用td的colspan, rowspan来进行分割的原理，构建一个按行分开的数据结果，利用这个数据结果按照table的加载顺序，一个一个td进行渲染。
而我们拿到的原始数据往往是像下面这样的：
[
{"id":"a2","pid":"","name":"Name",type:"tree",align:"left","dataType":"VARCHAR"},
{"id":"a3","pid":"","name":"Ticker",type:"ro",align:"left","dataType":"VARCHAR"},
{"id":"a4","pid":"","name":"Inception Date",type:"ro",align:"left","dataType":"VARCHAR"},
{"id":"a5","pid":"","name":"Expense Ratios"},
{"id":"b1","pid":"a5","name":"Gross expense ratio",type:"ro",align:"left","dataType":"VARCHAR"},
{"id":"b2","pid":"a5","name":"Net expense ratio",type:"ro",align:"left","dataType":"VARCHAR"},
{"id":"b3","pid":"a5","name":"Contractual waiver through",type:"ro",align:"left","dataType":"VARCHAR"},
{"id":"a6","pid":"","name":"Average annual return [%]"},
{"id":"c1","pid":"a6","name":"Lastest week as of 02/11/2011"},
{"id":"d1","pid":"c1","name":"YTD",type:"ro",align:"left","dataType":"INT"},
{"id":"d2","pid":"c1","name":"1-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"d3","pid":"c1","name":"3-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"d4","pid":"c1","name":"5-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"d5","pid":"c1","name":"10-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"d6","pid":"c1","name":"Since Inception",type:"ro",align:"left","dataType":"INT"},
{"id":"c2","pid":"a6","name":"Lastest quarter as of 12/31/2010 [unadjusted]"},
{"id":"e1","pid":"c2","name":"YTD",type:"ro",align:"left","dataType":"INT"},
{"id":"e2","pid":"c2","name":"1-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"e3","pid":"c2","name":"3-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"e4","pid":"c2","name":"5-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"e5","pid":"c2","name":"10-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"e6","pid":"c2","name":"Since Inception",type:"ro",align:"left","dataType":"INT"},
{"id":"c3","pid":"a6","name":"Lastest week as of 02/11/2011 [adjusted]"},
{"id":"f1","pid":"c3","name":"YTD",type:"ro",align:"left","dataType":"INT"},
{"id":"f2","pid":"c3","name":"1-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"f3","pid":"c3","name":"3-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"f4","pid":"c3","name":"5-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"f5","pid":"c3","name":"10-Year",type:"ro",align:"left","dataType":"INT"},
{"id":"f6","pid":"c3","name":"Since Inception",type:"ro",align:"left","dataType":"INT"},
{"id":"a7","pid":"","name":"Last return [%]",type:"ro",align:"left","dataType":"VARCHAR"}
]
我这里为了让每条数据之间的父子关系清晰一点，把子栏目的数据都堆到了父栏目下面。但是实际上，我们拿到的数据也应该按照这个顺序进行排列，否则你怎么确定父栏目与父栏目之间的顺序，子栏目与子栏目之间的顺序。当然，如果更加理想化，我们可以增加一个order/sort字段，用来保存排列顺序，并可以通过这个字段进行数组元素的排序计算，这样就不怕给的原始数据是随机排序的了。但是，我们本文仍然把这种情况排除，我们假设data api返回的数据就是上面这样的，已经确定好顺序了。
下面就是我进行处理的javascript代码，需要在node下运算，或者改写成可以在浏览器下运行的函数。
'use strtic';
require('jquery');
module.exports = function (origin) { // deep copy origin data, and origin data will not be change
var data = $.extend([],origin);
var origin = {};
for(var i = 0,len = data.length;i < len;i ++) {
var item = data[i];
item.children = [];
item.level = 1;
origin[item.id] = item;// change data to key=>value
}
/*
* build table tr
* find item children
* find item level
*/
var _nodes_ = [];
// add child to parent's children
for(var i = 0,len = data.length;i < len;i ++) {
var item = data[i];
if(item.pid != "") {
origin[item.pid].children.push(item.id);
}
}
function pushEndNodeToAncestors(item) {
var id = item.id;
var pid = item.pid;
if(pid == "" && item.children.length == 0) { // only one level (top) item
return;
}
while(pid != "") {
if(!_nodes_[pid]) _nodes_[pid] = [];
if(_nodes_[pid].indexOf(id) < 0) _nodes_[pid].push(id);
item = origin[pid];
pid = item.pid;
}
}
function pushLevelOfAncestors(item) {
var level = 1;
while(true) {
if(level > item.level) { // if this item is the same parent of different children
item.level = level;
}
if(level > headerRowsTotalCount) {
headerRowsTotalCount = level;
}
if(item.pid == "") {
break;
}
item = origin[item.pid];
level ++;
}
}
var headerRowsTotalCount = 1;
for(var i = 0,len = data.length,index = 0;i < len;i ++) {
var item = data[i];
if(item.children.length == 0) { // end nodes
item.index = index;
index ++;
pushEndNodeToAncestors(item);
pushLevelOfAncestors(item); // get headerRowsTotalCount at the same time
}
}
var headerRows = new Array(headerRowsTotalCount);
for(var i = 0,len = data.length;i < len;i ++) {
var item = data[i];
var nodes = _nodes_[item.id];
// kids
item.kids = item.children ? item.children.join(',') : "";
// (end)nodes
item.nodes = nodes ? nodes.join(',') : "";
// colspan
var colspan = 1;
if(nodes) {
colspan = nodes.length;
}
item.colspan = colspan;
// rowspan
var rowspan = 1;
if(item.pid == "") {
rowspan = 1 + (headerRowsTotalCount - item.level); // roots rowspan
}
else {
rowspan = origin[item.pid].level - item.level;
}
item.rowspan = rowspan;
// push item into table tr row
var row = headerRowsTotalCount - (item.level + item.rowspan - 1);
if(!headerRows[row]) headerRows[row] = [];
headerRows[row].push(item);
}
return headerRows;
}
完成上面的运算之后，实际上，我们得到的是一个3xn的数组，数组整体上有三个元素，每个元素都是一个数组，而这个数组中存放的，就是每一行tr内应该显示的td相关信息。接下来，我们把这个数据结果赋值给data，并在页面内进行table的构建：
var td = '<td colspan="{%s}" rowspan="{%s}" align="{%s}" data-id="{%s}" data-pid="{%s}" data-kids="{%s}" data-nodes="{%s}" data-index="{%s}" title="{%s}" class="header-cell"><div class="header-name">{%s}</div></td>';
var table = '';
for(var i = 0,len = data.length;i < len;i ++) {
var rowItems = data[i]; table += '<tr>';
for(var c = 0,leng = rowItems.length;c < leng;c ++) {
var item = rowItems[c];
table += sprintf(td,item.colspan,item.rowspan,item.align,item.id,item.pid,item.kids,item.nodes,item.index,item.name,item.name);
}
table += '</tr>';
}
sprintf是我自己写的一个函数，用来实现和c语言中sprintf一样的功能（只能替换{%s}），你也可以自己写过。这样，就可以在页面内构建能够分栏的tr行了，把它们插入到你需要显示的地方即可。
2016-07-26 3148
