Comparing version 14 and version 13

h3. Simple examples

h4. Query all records of a given model



  
    , 
    , 
     

  



h4. Simple search with conditions



  
    
      , 
      , 
       

    
    Number of records returned: 
  



h3. Summary of the tags shown

h4. model tag

Attribute:
* *name*: (required) specify model name here

h4. model:find tag

There are two main operation modes for model:find:

* if *id* attribute was given that it returns the record with the given id
* if no *id* was specified than a group of records will be returned

Either modes support the same tags.

* *limit*, *order*, *conditions* attributes will be passed to Model.find(...)

If *distinct* attribute was given than the following query will run: SELECT DISTINCT(*distinct*) FROM model WHERE *conditions* etc...

Furthermore, there is a special page type called *Filter* that may give further filtering conditions. More on that later. 

h3. Functions that may be called on the returned data (or on the Model itself)

What described above is very basic, but real life may require more complex calculations. To support that model_tags gives you several possibilities:

* You may create class funcions (methods) that may be called using a special tag *function*
* You may create instance functions (methods) that may be called on the result records

This leads to potential secutity issues, that will be addressed in a very basic fashion. Now lets see this in action.

h4. Class functions

First you need to prepare your model like this:


class Product < ActiveRecord::Base

  def self.myfunction(params=nil,conditions=nil)
    "returned value"
  end

  def self.otherfunction(params=nil,conditions=nil)
    ["value1","value2"]
  end

  def self.thirdfunction(params=nil,conditions=nil)
    { 'key' => 'value', 'key2' => 'value2' } 
  end

  def self.fourthfunction(params=nil,conditions=nil)
    Product.find(...whatever...)
  end

  def self.function_is_allowed_to?(fun,user)
    ['myfunction','otherfunction','thirdfunction', 'fourthfunction'].include?(fun)
  end

end


* *myfunction* returns a string that maybe displayed this way



  
    
    Great! Returned a real value...
  



* *otherfunction* returns an aray that may be displayed this way



  
    , 
    Number of returned items: 
  



please note the difference bw *each:value* and *each,value*

* *thirdfunction* returns a hash, that may be displayed this way:



  
    
    
  



* *fourthfunction* returns an array of Products:



  
    
        , 
 
    
    Number of returned products: 
  



h4. Instance functions

Instance functions may be created like class functions. They may return a single string, an array of values, a hash, an array of hashes or model instances. Same game. Prepare your model almost like above:


class Product < ActiveRecord::Base

  def myfunction(params=nil,conditions=nil)
    ["value1","value2"]
  end

  def function_is_allowed_to?(fun,user)
    ['myfunction'].include?(fun)
  end

end


* *myfunction* returns an aray that may be displayed this way



  
    
      
        , 
        Number of returned items: 
      
    
  



The important point here is that *function* tag is placed inside *model:find:each* instead of *model*. In the latter case the function is called on the Model class, in the former case on the returned Model instance. *params=nil,conditions=nil* parameters may be used to pass parameters and conditions to the function. 

* *params* is an array that is the value of the attribute *params* split on commas like this: params="1,2,3" => ["1","2","3"]
* *conditions* is the combined conditions given to the *find* tag and represented by the Filter url.

h3. Filter page type and tags

This feature allows you to create a specific page that processes the children url path as an SQL filter condition. To make this happen the following actions must be taken:

* create a page with the type: 'Filter' (here I assume its url is /filter)
* the page content would be something like:



  
    
      
        ....
      
    
  



If someone displays the following url /filter/price:e:100 than the code above is equivalent to this:



  
    ....
  



Thus the url part *price:e:100* is equivalent to *price=100* condition. Even better, different path components are combined to a single SQL condition. As shown the conditions are encoded like Field:Operation:Argument. The list of possible Operation values are:

* * e * : Equals
* * g * : Greater than
* * G * : Greater or equal
* * l * : Less than
* * L * : Less or equal
* * a * : String starts with
* * z * : String ends with
* * c * : Contains
* * n * : Is null
* * N * : Is not null

Null and not null conditions are treated in a special way, becuase Rails often stores empty strings rather than real null values. Because of that they means both empty string and null value. Also note that the Argument value is ignored, but must not be empty for null conditions.

Filter conditions may be enumerated, counted, listed and relative url may be displayed. ("More on this here...":http://model-tags.rubyforge.org/svn/trunk/extensions/model_tags/app/models/filter_page.rb)




Note: the result of /filter/price:e:100 call will be cached just like any other urls. This is on purpose. One might create a product catalog based on this feature and the distinct tag. It is desired not to query the database for each specific product category/filtered list.

h3. Container to store Model entities

The SiteController that handles static pages disables session support for performance reasons. It also provides caching features. I like both features, so I didn't want to change that. Still, sometimes part of the page should be created dynamically, while most of them may be cached. One such example is a shopping basket. To solve this I created special tags and a controller.

The idea is to render part of the page using AJAX javascript and handle the basket with a different controller while the container page is still rendered by the SiteController.

To use this feature you need to follow these steps:

* create a layout with content-type: text/html and only a  tag inside (assume this will be called SameAsContent)

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