# How to convert map of list to map of map? **URL:** \ **Category:** Terraform\ **Created:** [February 26, 2022, 1:01am UTC](https://discuss.hashicorp.com/t/how-to-convert-map-of-list-to-map-of-map/36263 "2022-02-26T01:01:10Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![BlueJapan](https://avatars.discourse-cdn.com/v4/letter/b/c67d28/32.png) [@BlueJapan](https://discuss.hashicorp.com/u/BlueJapan)\ **Post date:** [February 26, 2022, 1:01am UTC](https://discuss.hashicorp.com/t/how-to-convert-map-of-list-to-map-of-map/36263/1 "2022-02-26T01:01:10Z")
I am new to Terraform. ```auto variable "list" { default = { a = ["10"] b = ["20"] } } variable "list1" { default = { a = { c = "hello" } b = { d = "world" } } } ``` I’d like to have this as output. ```auto out = { a = { e = ["10"], c = "hello" } b = { f = ["20"], d = "world" } } ``` When i do this, it only prints out the hello world ```auto output "out" { value = {for k,v in merge(var.list, var.list1): k => v} } ``` ```auto out = { a = { c = "hello" } b = { d = "world" } } ``` How to achieve this? I think I don’t know how to convert var.list from map of list to map of map? Thanks. ###########Update: thanks @apparentlymart Currently, I already have an output can produce this: ```auto subnets_output = { "EU2" = { aks = [ "10.1.1.0/24", ] private_endpoints = [ "10.1.1.2/24", ] } } ``` I would love to achieve an output look like this, ```auto subnets_output2 = { aks = { cider = ["10.1.1.0/24"], type = "test" }, private_endpoints = { cider = ["10.1.2.0/24"], type = "base" } } ``` What I have now is: ```auto ##from local value locals = { aks = { type = "test" } private_endpoints = { type = "base" } } ``` ---
**Author:** ![apparentlymart](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/apparentlymart/32/702_2.png) [@apparentlymart](https://discuss.hashicorp.com/u/apparentlymart)\ **Post date:** [February 26, 2022, 1:41am UTC](https://discuss.hashicorp.com/t/how-to-convert-map-of-list-to-map-of-map/36263/2 "2022-02-26T01:41:16Z")
Hi @BlueJapan, There isn’t a single function for this situation, because what you want to achieve here is quite a specialized operation. I’m also not sure I fully understand your requirement, because I don’t see any rule in your description to decide the attribute names `e` and `f`. It might be easier to talk about this if we have realistic names for whatever problem you are really trying to solve, but I’ve made a _guess_ at what might be a suitable answer for you here: ```auto locals { all_keys = setunion(keys(var.list), keys(var.list2)) out = { for k in local.all_keys : k => { from_list = try(var.list[k], null) from_list1 = try(var.list1[k], null) } } } ``` The value of `local.out` should then be the following: ```auto { a = { from_list = ["10"] from_list1 = { c = "hello" } } a = { from_list = ["20"] from_list1 = { d = "world" } } } ``` This is the closest I can understand what you mean by your requirements, but I know that this doesn’t exactly match your example output. If the above doesn’t help you make progress, it would help if you could share a different example that is more realistic for what you are trying to achieve, using the real nouns that are involved, so that I can see more clearly how your intended result should relate to your input data. ---
**Author:** ![BlueJapan](https://avatars.discourse-cdn.com/v4/letter/b/c67d28/32.png) [@BlueJapan](https://discuss.hashicorp.com/u/BlueJapan)\ **Post date:** [February 26, 2022, 2:05am UTC](https://discuss.hashicorp.com/t/how-to-convert-map-of-list-to-map-of-map/36263/3 "2022-02-26T02:05:40Z")
Just updated my question above. Thanks a lot. ---
**Author:** ![BlueJapan](https://avatars.discourse-cdn.com/v4/letter/b/c67d28/32.png) [@BlueJapan](https://discuss.hashicorp.com/u/BlueJapan)\ **Post date:** [February 26, 2022, 3:12am UTC](https://discuss.hashicorp.com/t/how-to-convert-map-of-list-to-map-of-map/36263/4 "2022-02-26T03:12:18Z")
(1) ```auto output "lst_output2" { value = merge({for key in keys(var.lst): key => var.lst[key]}, {for key in keys(var.lst1) : key => var.lst1[key]}) } ``` Still not working… (2) But this is the closest i got ```auto value = {for key in keys(var.lst): key => merge(var.lst[key], {key:var.lst1[key]})} ``` The output look like this: ```auto output2 = { + aks = { + key = [ + "10.1.1.0/24", ] + type = "test" } + production = { + key = [ + "10.1.2.0/24", ] + type = "base" } } ``` ---
**Author:** ![apparentlymart](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/apparentlymart/32/702_2.png) [@apparentlymart](https://discuss.hashicorp.com/u/apparentlymart)\ **Post date:** [March 1, 2022, 2:22am UTC](https://discuss.hashicorp.com/t/how-to-convert-map-of-list-to-map-of-map/36263/5 "2022-03-01T02:22:29Z")
Hi @BlueJapan, I think you are saying that the `subnets_output` you included is a local value, so would be `local.subnets_output`. You then have another local value whose name you didn’t include which contains the `aks` and `private_endpoints` attributes, with `type` attributes inside each one. Let’s call that `local.other_attributes` just so I have something to call it in this example. So my understanding of the requirement is that you want to add an extra attribute called `cider` to each of the objects in `local.other_attributes`, while preserving the `type` attribute and presumably any other attributes that might appear there. Here’s what I would do for that requirement: ```auto locals { result = { for k, attrs in local.other_attributes : k => merge( attrs, { cider = local.subnets_output["EU2"][k] } ) } } ``` ---
**Author:** ![ChristosDragios](https://sea2.discourse-cdn.com/hashicorp/user_avatar/discuss.hashicorp.com/christosdragios/32/30026_2.png) [@ChristosDragios](https://discuss.hashicorp.com/u/ChristosDragios)\ **Post date:** [September 20, 2022, 7:00pm UTC](https://discuss.hashicorp.com/t/how-to-convert-map-of-list-to-map-of-map/36263/6 "2022-09-20T19:00:31Z")
Hi, about the first snippet, is the following a variable type of list(object) or something else? “variable “list1” { default = { a = { c = “hello” } b = { d = “world” } } }”