Visualforce Developer Guide
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Reference Apex Maps and Lists
Visualforce pages that use dynamic bindings can reference the Apex Map and List
data types in their markup.
For example, if an Apex List is defined
as:
public List<String> people {
get {
return new List<String>{'Winston', 'Julia', 'Brien'};
}
set;
}
public List<Integer> iter {
get {
return new List<Integer>{0, 1, 2};
}
set;
}<apex:repeat value="{!iter}" var="pos">
<apex:outputText value="{!people[pos]}" /><br/>
</apex:repeat>Similarly, if you have this Apex Map:
public Map<String,String> directors {
get {
return new Map<String, String> {
'Kieslowski' => 'Poland',
'del Toro' => 'Mexico',
'Gondry' => 'France'
};
}
set;
}<apex:repeat value="{!directors}" var="dirKey">
<apex:outputText value="{!dirKey}" /> --
<apex:outputText value="{!directors[dirKey]}" /><br/>
</apex:repeat>Use dynamic references to lists and maps in an <apex:inputText> tag to create forms using data that isn’t in your organization’s custom objects. Working with a single map can be much simpler than creating a series of instance variables in an Apex controller or creating a custom object just for the form data.
Here’s a Visualforce page that uses a
map to hold form data for processing by a custom
controller.
<apex:page controller="ListsMapsController">
<apex:outputPanel id="box" layout="block">
<apex:pageMessages/>
<apex:form >
<apex:repeat value="{!inputFields}" var="fieldKey">
<apex:outputText value="{!fieldKey}"/>:
<apex:inputText value="{!inputFields[fieldKey]}"/><br/>
</apex:repeat>
<apex:commandButton action="{!submitFieldData}"
value="Submit" id="button" rerender="box"/>
</apex:form>
</apex:outputPanel>
</apex:page>
And here’s a simple controller that
works with the
form.
public class ListsMapsController {
public Map<String, String> inputFields { get; set; }
public ListsMapsController() {
inputFields = new Map<String, String> {
'firstName' => 'Jonny', 'lastName' => 'Appleseed', 'age' => '42' };
}
public PageReference submitFieldData() {
doSomethingInterestingWithInput();
return null;
}
public void doSomethingInterestingWithInput() {
inputFields.put('age', (Integer.valueOf(inputFields.get('age')) + 10).format());
}
}A Map can contain references to sObjects or
sObject fields. To update those items, reference a field name in the input
field.
public with sharing class MapAccCont {
Map<Integer, Account> mapToAccount = new Map<Integer, Account>();
public MapAccCont() {
Integer i = 0;
for (Account a : [SELECT Id, Name FROM Account LIMIT 10]) {
mapToAccount.put(i, a);
i++;
}
}
public Map<Integer, Account> getMapToAccount() {
return mapToAccount;
}
}<apex:page controller="MapAccCont">
<apex:form>
<apex:repeat value="{!mapToAccount}" var="accNum">
<apex:inputField value="{!mapToAccount[accNum].Name}" />
</apex:repeat>
</apex:form>
</apex:page>Unresolved Dynamic References
Keep in mind the following issues that can arise at run time if a dynamic reference doesn’t resolve:
- If there isn’t a value mapped to a particular key or the value is null, the Visualforce page returns an error
message. For example, with this
controller:This page causes an error at run time.
public class ToolController { public Map<String, String> toolMap { get; set; } public String myKey { get; set; } public ToolController() { Map<String, String> toolMap = new Map<String, String>(); toolMap.put('Stapler', 'Keeps things organized'); toolMap.put('Notebook', null); } }<apex:page controller="ToolController"> <!-- Both outputText values render an error on the page --> <apex:outputText value="{!toolMap['Paperclip']}" /> <apex:outputText value="{!toolMap['Notebook']}" /> </apex:page> - If the key is null, the Visualforce page
renders an empty string. For example, using the same controller as above, this
page shows an empty
space.
<apex:page controller="ToolController"> <!-- This renders a blank space --> <apex:outputText value="{!toolMap[null]}" /> </apex:page>