Freemarker iterating over hashmap keys

Question

Freemarker has two collection datatypes  lists and hashmaps Is there a way to iterate over hashmap keys just as we do with lists   So if I have a var with data lets say   user       name    user    email    looser everything com    homepage    http   nosuchpage org      I would like to print all the user s properties with their value  This is invalid  but the goal is clear    lt  list user props   as prop gt      prop      user get prop    lt   list gt

User · Answer

You can use a single quote to access the key that you set in your Java program.

If you set a Map in Java like this

Map<String,Object> hash = new HashMap<String,Object>();
hash.put("firstname", "a");
hash.put("lastname", "b");

Map<String,Object> map = new HashMap<String,Object>();
map.put("hash", hash);

Then you can access the members of 'hash' in Freemarker like this -

${hash['firstname']}
${hash['lastname']}

Output :

a
b

User · Answer

Edit  Don t use this solution with FreeMarker 2 3 25 and up  especially not  get prop   See other answers   You use the built-in keys function  e g  this should work    lt  list user keys as prop gt        prop      user get prop    lt   list gt

User · Answer

Iterating Objects  If your map keys is an object and not an string  you can iterate it using Freemarker   1  Convert the map into a list in the controller   List lt Map Entry lt myObjectKey  myObjectValue gt  gt  convertedMap    new ArrayList originalMap entrySet       2  Iterate the map in the Freemarker template  accessing to the object in the Key and the Object in the Value    lt  list convertedMap as item gt       lt  assign myObjectKey   item getKey    gt       lt  assign myObjectValue   item getValue    gt             lt   list gt

User · Answer

Since 2 3 25  do it like this    lt  list user as propName  propValue gt      propName      propValue   lt   list gt    Note that this also works with non-string keys  unlike map key   which had to be written as map api get key  then    Before 2 3 25 the standard solution was    lt  list user keys as prop gt      prop      user prop    lt   list gt    However  some really old FreeMarker integrations use a strange configuration  where the public Map methods  like getClass  appear as keys  That happens as they are using a pure BeansWrapper  instead of DefaultObjectWrapper  whose simpleMapWrapper property was left on false  You should avoid such a setup  as it mixes the methods with real Map entries  But if you run into such unfortunate setup  the way to escape the situation is using the exposed Java methods  such as user entrySet    user get key   etc   and not using the template language constructs like  keys or user key

User · Answer

If using a BeansWrapper with an exposure level of Expose SAFE or Expose ALL  then the standard Java approach of iterating the entry set can be employed   For example  the following will work in Freemarker  since at least version 2 3 19     lt  list map entrySet   as entry gt       lt input type  hidden  name    entry key   value    entry value     gt   lt   list gt    In Struts2  for instance  an extension of the BeanWrapper is used with the exposure level defaulted to allow this manner of iteration

User · Answer

For completeness  it s worth mentioning there s a decent handling of empty collections in Freemarker since recently   So the most convenient way to iterate a map is    lt  list tags gt   lt ul class  posts  gt       lt  items as tagName  tagCount gt           lt li gt   tagName     tagCount   lt  li gt       lt   items gt   lt  ul gt   lt  else gt       lt p gt No tags found  lt  p gt   lt   list gt    No more  lt  if     gt  wrappers

User · Answer

FYI  it looks like the syntax for retrieving the values has changed according to   http   freemarker sourceforge net docs ref builtins hash html   lt  assign h     name   mouse    price  50  gt   lt  assign keys   h keys gt   lt  list keys as key gt   key      h key     lt   list gt

[java] Freemarker iterating over hashmap keys

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