The map block

Use the map block to convert a list into a map (key-value pair) or a nested map within a globals or lets block. You can use the map block to store configuration data in variables and pass them between different parts of the infrastructure code. If you have multiple objects in a list with one or more identical keys, you can merge values corresponding to the identical keys while iterating over them. For each object in the list, you can access the previous or the current value of any of its keys. In the for-each iteration, the iterator (default name element) is an object with the following properties:

element = {
    new = <current element>
    old = <previous set value in the object> || null
}

Arguments

The map block can only be used inside the globals or lets block, requires one label and optionally accepts a value.

name	type	description
for_each	list(any)	The input list
key	string	The computed key
value	any	The value for the key
value	block*	value properties

The value block and the value attribute cannot be used together.

Syntax

globals {
  map totals {
    for_each = global.orders

    key = element.new.name

    value {
      total_spent = tm_try(element.old.total_spent, 0) + element.new.price
    }
  }
}

Examples

Let's convert the global.orders list below into a nested object organized by name and product.

globals {
  orders = [
    { name = "Morpheus", product = "sunglass", price = 100.5 },
    { name = "Trinity", product = "cape", price = 82.30 },
    { name = "Trinity", product = "necklace", price = 25.0 },
    { name = "Trinity", product = "sunglass", price = 100.5 },
    { name = "Anderson", product = "ollydbg", price = 30 },
    { name = "Morpheus", product = "boot", price = 65 },
    { name = "Anderson", product = "cape", price = 82.30 },
    { name = "Morpheus", product = "sunglass", price = 145.50 },
  ]
}

Structure those values by product for each name by using the nested map block as defined below:

globals {
  map totals {
    for_each = global.orders

    iterator = per_name

    key = per_name.new.name

    value {
      total_spent = tm_try(per_name.old.total_spent, 0) + per_name.new.price

      map per_product {
        for_each = [for v in global.orders : v if v.name == per_name.new.name]

        iterator = per_product

        key = per_product.new.product

        value {
          total = tm_try(per_product.old.total, 0) + per_product.new.price
        }
      }
    }
  }
}

It will result in the below object:

obj = {
  Anderson = {
    total_spent = 112.3
    per_product = {
      cape = {
        total = 82.3
      }
      ollydbg = {
        total = 30
      }
    }
  }
  Morpheus = {
    total_spent = 311
    per_product = {
      boot = {
        total = 65
      }
      sunglass = {
        total = 246
      }
    }
  }
  Trinity = {
    total_spent = 207.8
    per_product = {
      cape = {
        total = 82.3
      }
      necklace = {
        total = 25
      }
      sunglass = {
        total = 100.5
      }
    }
  }
}