freemark 技巧收集

写程序是 顺便收集一下吧

 

• has_content

 

说明：

It is true if the variable exists (and isn't Java null) and is not ``empty'', otherwise it is false. The meaning of ``empty'' depends on the concrete case. This follows intuitive common-sense ideas. The following are empty: a string with 0 length, sequence or hash with no subvariables, a collection which has passed the last element. If the value is not a string or sequence or hash or collection, then it counts as non-empty if it's a number or a date or a boolean (e.g. 0 and false are not empty), otherwise it counts as empty. Note that when your data-model implements multiple template model interfaces you may get unexpected results. However, when in doubt you can use always use expr!?size > 0 or expr!?length > 0 instead of expr?has_content.

This buit-in is exceptional in that you can use the parentheses trick like with the default value operator. That is, you can write both product.color?has_content and (product.color)?has_content. The first doesn't handle the case when product is missing, the last does.

 

    这个感觉挺实用的，一般如果检查一个 BOOLEAN 变量的时候 用

写道

"name":"row.isTrue?string('是','否')", "escape":false}

    就够了

 

   但是在检查其他的时候，比如 string类型字段是否为空时 并且 不是单纯在if中进行判断（这个用 (varis.attr)?? 就可以了）就可以使用

 

写道

((row.corporation)?has_content)?string('是','否')