# How to configure a computed property within a TypeList element

**URL:** <https://discuss.hashicorp.com/t/how-to-configure-a-computed-property-within-a-typelist-element/4187>\
**Category:** Terraform Providers\
**Created:** [November 26, 2019, 9:25am UTC](https://discuss.hashicorp.com/t/how-to-configure-a-computed-property-within-a-typelist-element/4187 "2019-11-26T09:25:31Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![oscarDovao](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/oscardovao/32/3332_2.png) [@oscarDovao](https://discuss.hashicorp.com/u/oscarDovao)\
**Post date:** [November 26, 2019, 9:25am UTC](https://discuss.hashicorp.com/t/how-to-configure-a-computed-property-within-a-typelist-element/4187/1 "2019-11-26T09:25:31Z")

</div>

Hi,  
I’m working on a official provider.  
We are trying to implement a new element within an existing resource which looks like this…

```auto
"waf": {
	Type: schema.TypeList,
	Optional: true,
	MaxItems: 1,
	Elem: &schema.Resource{
		Schema: map[string]*schema.Schema{
			"response_object": {
				Type: schema.TypeString,
				Required: true,
			},
			"prefetch_condition": {
				Type: schema.TypeString,
				Required: true,
			},
			"waf_id": {
				Type: schema.TypeString,
				Computed: true,
			},
		},
	},

```

‘’’

However the computed property “waf\_id” doesn’t seem to be recognised and therefore it doesn’t show on the plan (plan bellow).

```auto

      + waf {
          + prefetch_condition = "Waf_Prefetch"
          + response_object = "WAF_Response"
        }

```

Is there a way I can make Terraform recognise “waf\_id” as computed property?

Any advice would be greatly appreciated.

Many thanks,