Documentation Mailing Lists FAQ Frequently Asked Questions v2

Topic: Constants

This example uses 1 view, 3 categories, and 2 levels of constants. The catgories are not important but maybe you like to use them so I left them in there.

The view below manages a two level side bar menu. It highlights the branch you are in and the (sub)item you have selected. Example can be seen here http://pi.gn.apc.org

The constants are used as the menu entries. You have to use hierarchical constants and define the constants like this:

Level 0: Name      Value 
         Terrorism Terrorism 
         Policy    Policy ... 

Level 1: Name                        Value
         Politics of Terrorism       Terrorism::Politics of Terrorism Defining 
         Terrorism and Emergencies   Terrorism::Terrorism and Emergencies 
         IGOs and Laundering Policy  Policy::IGOs and Laundering Policy
         ... 

Now create a new constants view Paste the text below into Odd Rows.  Set the Group by to "Value Select" the hierarchical constant group created above View 342 is the listing view I use to display items from my slice.

The slice has 3 categories. This menu only manages the selection of the first category (category........) which is set to use the constant group created above. Further it's first confition is set to LIKE (name of category........). You will have to replace 342 in the text below with your listing view. You can leave away most of the {country}-stuff. To work this just needs {theme} and {_parent_}.

TODO: use better names for the aliases. 'theme' and 'country' might be substrings in the constants. That would cause havoc! All left to do now is to create your style sheet. Have fun!

----------SNIP SNIP----------

{switch({_#LEVEL##_})0:<br>
  {switch({theme}).*theme.*:
    <div class="constView_ContentThemes_ListEntry">
  :{_#NAME###_}.*:
    <div class="constView_ContentThemes_ListEntry_Hl">
    :<div class="constView_ContentThemes_ListEntry{switch({_parent_}){_#NAME###_}.*:_Hl}">
  }
  <a href="/index.shtml?cmd[342][]=c-1-{_#NAME###_}&als[theme]={_#NAME###_}&conds[1][category........]={_#NAME###_}{switch({_#VALUE##_}){theme}.*:&als[_parent_]={theme}}{switch({country}).*country.*::&cmd[342][]=c-3-{country}&als[country]={country}&conds[3][category.......2]={country}}" class="constView_ContentThemes_ListEntry_link">_#NAME###_</a>
  </div>
:1:<!--{theme}--_#VALUE##_--_#NAME###_-->
  {switch({_parent_}).*_parent_.*:
    {switch({theme}).*theme.*::
      {switch({_#VALUE##_}){theme}.*:<div class="constView_ContentThemes_SubListEntry{switch({theme}){_#NAME###_}.*:_Hl}"><a href="/index.shtml?cmd[342][]=c-1-{_#NAME###_}&als[theme]={_#NAME###_}&conds[1][category........]={_#NAME###_}&als[_parent_]={theme}{switch({country}).*country.*::&cmd[342][]=c-3-{country}&als[country]={country}&conds[3][category.......2]={country}}" class="constView_ContentThemes_SubListEntry_link">{_#NAME###_}</a></div>}
    }
  :{switch({theme}).*theme.*::
    {switch({_#VALUE##_}){_parent_}.*:<div class="constView_ContentThemes_SubListEntry{switch({theme}){_#NAME###_}.*:_Hl}"><a href="/index.shtml?cmd[342][]=c-1-{_#NAME###_}&als[theme]={_#NAME###_}&conds[1][category........]={_#NAME###_}&als[_parent_]={_parent_}{switch({country}).*country.*::&cmd[342][]=c-3-{country}&als[country]={country}&conds[3][category.......2]={country}}" class="constView_ContentThemes_SubListEntry_link">{_#NAME###_}</a></div>}
    }
  }
}

----------SNIP SNIP----------

Some fields have a predefined set of possible values --- a constant group. These are usually shown in a select box, multiple check / radio boxes etc. Edit them in Slice Admin -- Fields -- Constants -- Edit / New.

Categories are constants with some special properties. The constant table structure is:

CREATE TABLE constant (
   id char(16) NOT NULL,
   group_id char(16) NOT NULL,
   name char(150) NOT NULL,
   value char(150) NOT NULL,
   class char(16),
   pri smallint(5) DEFAULT '100' NOT NULL,
   PRIMARY KEY (id),
   KEY group_id (group_id)
);

• group_id is the constant group name
• name is shown on the Add / Edit item page in the select box or other controls
• value is stored in database (table content) and used by slice.php3, view.php3 etc.
• class_id is used only by categories. It is an identifier of some parent - APC wide - category, usefull when importing items between slices.
• pri is the priority used to sort in the select box etc.

When to use different name and value

For example the "State" select box (if you want to see it on input form) has the names and values of:

Another example, more real-life - colors select box. There can be names of "Red", "blue", "very bright green", ... and values will be "#FF0000", "#0000FF", "#EEFFEE". In input form you see Red... and on page is then #FF0000

The third example is kind of hint. Suppose you want to have different kinds of item - for example "public", "private", "other" and you want to see this words on compact view. No problem, but you want to see each in different color. So you can define:

Order Categories on Input Form as You Wish

You can set the priority order in the constant editing page, and then if you want the output in this order as well, then in the View set the sorting to be "Ascending (or Descending) by Priority"

Propagate changes into current items

Usually if you change a constant value, the current items in the database remain the same. By checking this box you force the changes to be made on the items too. If you change "red" to "cyan", all items with color "red" will be changed to "cyan".

Remember that the constants may be shared by several slices --- if you change a value, the changes may be propagated to some places which you didn't count with. Another danger is that if there were some items with "cyan" before, you can never ever find which item are converted from "red" and which are not.

Changing the constant name doesn't have any effect in the database but changes the look in all Edit / New item pages using the constant group.

Displaying list of constants on a page

This FAQ interface was developed by Jason at Commons.ca

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