> For the complete documentation index, see [llms.txt](https://doc.telosys.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.telosys.org/bundles/code-snippets.md).

# Code snippets

### Iterate over all entities defined in the model

```velocity
#foreach( $e in $model.allEntites )
		...
#end
```

### Iterate over entity attributes

```velocity
#foreach( $attribute in $entity.attributes )
		...
#end

#foreach( $attribute in $entity.keyAttributes)
		...
#end

#foreach( $attribute in $entity.nonKeyAttributes)
		...
#end
```

### Iterate over entity links

```velocity
#foreach( $link in $entity.links )
		...
#end

```

### Execute a ".vm" file located in a model folder

The function "$fn.fileFromModel(fileName)" returns an instance of "file" located in the current model. If the file exists, its content is loaded and evaluated with "#evaluate" directive.

```velocity
#set( $file = $fn.fileFromModel("model-init.vm") )
#if($file.exists())#evaluate($file.loadContent())#end
```

### Get the class of an object

As all Velocity references ( "$xxx" ) are references of Java objects, sometimes it could be useful to know the object's class. To do this, just use "**class.name**" (full name with package) or "**class.simpleName**" (only the class name without package)

```velocity
#set( $v = 12 )
$v.class.name 
$v.class.simpleName 

#set( $s = "abc" )
$s.class.name 
$s.class.simpleName 

$entity.class.name 

$now.class.simpleName 
```

### Generate a file only once

Sometimes it can be useful to make sure you only generate a file once to avoid overwriting manual changes after project bootstrapping. Since Telosys 3.3.0 you can do that with **#cancel** directive.

```velocity
##--- NB : do not rewrite the file if it already exists
#if($target.outputFileExists() )#cancel("File already exists")#end

```

### Maps of lists 

With Velocity, you can create a "map" of "anything". A map can contain any object, even lists.

```velocity
## --- Example 1 :
#set( $list1 = [ 0, 1, 2 ] )
#set( $list2 = [ "", "A", "B", "C", "D" ] )
## A map of lists :
#set( $m = {"k1" : $list1 , "k2" : $list2} )

## --- Example 2 (literal):
#set( $m2 = {
  "int" : [ 100, 200, 300 ] , 
  "str" : [ "AAA", "BB", "CCC", "D" ] 
  } )

## --- Usage 
$m["k2"]
$m["k2"][2]

$m2["int"][1]
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://doc.telosys.org/bundles/code-snippets.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.