How to dynamically access objects in ftl? - templates

Question

I have my data model stored in yaml as below
users:
- "u1"
- "u2"
u1:
name: "user1"
age: 25
u2:
name: "user2"
age: 26
I am trying to use the below template (ftl) to generate user records
[
<#list users as user>
{
"username": "${${user}.name}"
"userage": "${${user}.age}"
},
</#list>
]
my final output should look like:
[
{
"username": "user1",
"userage": "25"
},
{
"username": "user2",
"userage": "26"
}
]
How to achieve this? I am getting below error

Answer 1

The expression you are looking for is .vars[user].name (where [] does the lookup by a dynamic key, and .vars is a special variable to refer to all your top-level variables). Then you can put that whole thing into ${} where that's needed. You can also do <#assign userObj = .vars[user]>, and then later just write userObj.name, and userObj.age. (Though, regrading the name choices, I would use userId instead of user, and user instead of userObj.)
Last not least, the data-model should just be like this, if possible, and then everything is simpler, and less confusing:
users:
u1:
name: "user1"
age: 25
u2:
name: "user2"
age: 26
So then you can write something like users.u1.age. If the user ID is dynamic, and let's say it's in the userId variable, then you can write users[userId].age.

Answer 2

In FreeMarker Template Language (FTL), you can dynamically access objects in your data model using the square bracket notation, like this:
[
<#list users as user>
{
"username": "${user.name}"
"userage": "${user.age}"
},
</#list>
]
Here, the users list is accessed using users as the key in the data model. The user variable in the list directive holds each value of the list one at a time. To access the properties of the u1 and u2 objects, you use user.name and user.age.
This should produce the desired output:
[ {
"username": "user1",
"userage": "25" },
{ "username": "user2",
"userage": "26" }]