捕捉：内部/外部循环与抢劫 [英] Snap: inner/outer loops with heist

问题描述

我不确定我是否正确地在标题中表达了这个问题，但这是情况。
当表字段（模式）仅在运行时可用时，我需要创建一个带有heist的动态表。
所以通常情况下，当模式在compile时已知，我会这样做：

 < table> 
< row-splice> 
< tr> 
< td> < field1的/> < / TD> 
< td> < FIELD2 /> < / TD> 
< td> <字段3 /> < / TD> 
< / tr> 
< / row-splice> 
< / table> 
  

这就是当我在编译时知道字段数目和它们的名字。
我理解如何处理与'runChildrenWith'，'mapSplices'等处理程序中的所有内容...

现在我处于一种情况字段和模式的数量仅在运行时可用。
因此，据我所知，heist模板看起来像这样：

 < table> 
< row-splice> 
< tr> 
< field-splice> 
< td> <场强/> < / TD> 
< / field-splice> 
< / tr> 
< / row-splice> 
< / table> 
  

我很在意如何在处理程序中实现它。我假设我需要做两次'mapSplices' - 一个在另一个里面，对吗？因此，从经验上讲，这将是一个内部和外部循环/地图，对吗？

我如何在处理程序中执行此操作？

谢谢。

更新：

忘记提及架构可以在运行时间从数据库和可用：

  Table {tableName :: Text 
，tableFields :: [Text] 
 
 $ / code> 

但它并不是真的需要，因为数据来自无模式mongodb并被转换到Map：

  fromList [（FieldName1，Value1），（FieldName2，Value2），（ FieldName3，Value3）] 
  

Update2：



我尝试了一些没有运气的示例，我只是将所有数据都放在一个列中。
我只需要一个简单的内部和外部循环来动态地生成字段和行。
这不能简单：



 <％@ rows.each do | row | ％GT; 
< tr> 
 <％row.each do | field | ％GT; 
< td> <％= field％> < / TD> 
<％end％> 
< / tr> 
<％end％> 
  

Update3：

我终于破解了它经过长时间的周末休息...
这里是例子。它是特定的mongodb，我简直就是复制并粘贴它。
但是如果有人被内部/外部循环卡住了，我想这会有所帮助。

  showTableH :: AppHandler（）
 showTableH = do 
表<  -  liftIO $ fetchTable tname 
 docs<  -  liftIO $ getColList tname 
 let rowSplice doc = mapSplices（\ f  - > fieldSplice $ T.pack $ at f doc）（tableFields table）
 where fieldSplice field = runChildrenWithText [（field，field）] 
 let listRowsSplice = mapSplices（\d-> runChildrenWith [（fields，rowSplice d）]）docs 
 heistLocal（bindSplices [（rows， listRowsSplice）]）$ rendershow-table
  

解决方案

我认为这里的关键是使用mapSplices和runChildrenWith。我认为它看起来像这样：

  rowSplice = do 
 rows<  -  lift getRowsFromDB 
 mapSplices（\row  - > runChildrenWith [（field-splice，fieldSplice row）]）rows 
 fieldSplice rowId = do 
 fields<  -  lift $ getFieldsFromDB rowId 
 mapSplices \\ f  - > runChildrenWith [（field，fieldToText f）]）fields 
  

I am not sure if I phrased the question in the title correctly but here is the situation.. I need to create a dynamic table with heist when table fields (schema) are only available at run time. So usually, when the schema is known at compile, I would do something like this:

<table>
  <row-splice>
    <tr>
      <td> <field1/> </td>
      <td> <field2/> </td>
      <td> <field3/> </td>
    </tr>
  </row-splice>
</table>

That is when I know the number of fields and their names at compile time. I understand how to process all that in the handler with 'runChildrenWith', 'mapSplices' and so on ...

Now I am in a situation when the number of fields and schema are available only at run time. So the heist template, as I understand it, would look like this:

<table>
  <row-splice>
    <tr>
      <field-splice>
      <td> <field/> </td>
      </field-splice>
    </tr>
  </row-splice>
</table>

I am really stuck with how to implement it within the handler. I assume I would need to do 'mapSplices' twice - one inside the other, correct? So, empirically speaking, that would be an inner and outer loop/map, right?

How would I do this within handler??

Thanks.

Update:

Forgot to mention that schema can be retrieved at run time from the DB and available as:

Table { tableName   :: Text
      , tableFields :: [Text]
      }

But it is not really needed as data comes from schema-less mongodb and converted to Map:

fromList [("FieldName1","Value1"),("FieldName2","Value2"),("FieldName3","Value3")]

Update2:

I tried suggested examples with no luck I just get all my data in a single column. All I need is a simple inner and outer loop to generate fields and rows dynamically. It cannot be simpler then this:

<% @rows.each do |row| %>
  <tr>
  <% row.each do |field| %>
    <td> <%= field %> </td> 
  <% end %>
  </tr>
<% end %>

Update3:

I finally cracked it after a long weekend rest ... Here is the example. it is mongodb specific and I literally just copied and pasted it. But if someone gets stuck with inner/outer loops it would be helpful, I suppose.

showTableH :: AppHandler ()
showTableH = do
  table <- liftIO $ fetchTable tname
  docs <- liftIO $ getColList tname
  let rowSplice doc = mapSplices (\f -> fieldSplice $ T.pack $ at f doc) (tableFields table)
    where fieldSplice field = runChildrenWithText [("field", field)]
  let listRowsSplice = mapSplices (\d -> runChildrenWith [("fields", rowSplice d)]) docs
  heistLocal (bindSplices [("rows", listRowsSplice)]) $ render "show-table"

解决方案

I think the key here is using mapSplices along with runChildrenWith. I think it would look something like this:

rowSplice = do
    rows <- lift getRowsFromDB
    mapSplices (\row -> runChildrenWith [("field-splice", fieldSplice row)]) rows
fieldSplice rowId = do
    fields <- lift $ getFieldsFromDB rowId
    mapSplices (\f -> runChildrenWith [("field", fieldToText f)]) fields

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