Dictionary variables (Dictionary<TKey, TValue>) are collection type of variables of (key, value) pairs, in which the keys are unique. Think of the Address Book in your mobile phone, where each entry has corresponding data (name, phone number(s), email address, etc).
The data types for both keys and values have to be chosen when the variable is declared. Data types within dictionaries can be any of the supported variables (String, Int32, etc) including Dictionary<TKey, TValue>.
The operations that are most often associated with dictionaries are:
- Adding and deleting (key, value) pairs.
- Retrieving the value associated with a key.
- Re-assigning new values to existing keys.
Methods for working with dictionary variables:
Initialization
As in the case of list variables, dictionary variables need to be initialized as well. For example, if we want to initialize a dictionary of String type of key and String type of value, we can add new Dictionary(Of String, String) inside the Default value field in the Variables panel or Data Manager panel for the respective variable, or use an Assign activity to assign the value to the variable within the workflow.
Adding Key-Value Pairs
VarName.Add(Key, Value) adds an item to an existing dictionary variable. Because Add doesn't return a value, we use the Invoke Method or Assign activity.
Removing Keys
VarName.Remove(Key) removes an item from the dictionary variable. It can be used in an Invoke Method activity.
Retrieving
VarName.Item(Key) returns the Dictionary item by its key.
VarName.Count returns an Int32 value of the number of Dictionary items.
VarName.ContainsKey(Key) checks if the item with the given key exists in the dictionary variable and returns a Boolean result.
To declare a dictionary, we need to create a variable with System.Collections.Generic.Dictionary as type. Then we select its key and value data types. Dictionaries, like lists, must be initialized after being declared. To assign keys and values to the dictionary variable, we can use the Assign activity. We can process items in our dictionary variable by using the For Each activity.
Source: UiPath Academy