One of the basic principles for implementing the FreeMarker engine is that the data model can only be accessed in read-only mode.
A value from a data model cannot be changed during template execution.
One of the consequences concerns the Hash type: FreeMarker can be used to create a Hash object literally but, once it is created, the object cannot be changed (click here for more details).
Example:
<#assign hashVal = {"attr1": "val1",
"attr2": "val2",
"attr3": "val3"} />
<#list hashVal as aKey, aVal>...</#list>
${hashVal["attr2"]}
<#-- It is possible to browse the hashVal values or access a hashVal attribute value but it is not easy to change a hashVal attribute value or add/delete an attribute -->
<#-- Inefficient solution for changing an attribute value -->
<#assign attrModified = "attr2" />
<#assign hashVal = hashVal + { attrModified : "val2Modified" }/>
<#-- Inefficient solution for deleting an attribute -->
<#assign hashVal = {"attr1": "val1",
"attr2": "val2",
"attr3": "val3"} />
<#assign attrToDelete = "attr2" , tmpHash = {} />
<#list hashVal as key, val>
<#if key != attrToDelete>
<#assign tmpHash = tmpHash + {key: val} />
</#if>
</#list>
<#assign hashVal = tmpHash />
This function returns a Hash-type object with basic add, change and delete methods. It can take an argument:
- Either no parameter: the returned Hash object is empty,
- Or a Hash object: the returned Hash object is a copy. These attributes/values are identical to the Hash object passed as a parameter,
- a String-type key and a value of any type: the returned Hash type will contain a single attribute, the name of which is the value of the key passed as a parameter and the associated value of which is that passed as a parameter.
Parameters
Hash |
originalHash |
The returned Hash object contains the originalHash attribute/value pairs. |
Optional |
All types |
value |
Attribute value called "key" in the returned object |
Optional. Mandatory if the first parameter is String type |
For example
<#-- Create empty hash -->
<#assign newHash = hardisCore.createSimpleHash() />
Size of newHash:${newSeq?keys?size}
<#-- Create Hash from another Hash -->
<#assign originalHash = {"attr1": 1, "attr2":true} />
<#assign newHash = hardisCore.createSimpleHash(originalHash) />
Size of newHash:${newSeq?keys?size}
<#-- Create Hash with one sub variable -->
<#assign newHash = hardisCore.createSimpleHash("myKey", "myValue") />
Size of newHash:${newSeq?keys?size}