Dictionary Data type
Version: Available or changed with runtime version 1.0.
Represents an unordered collection of keys and values. The Dictionary data type is optimized for fast lookup of values.
Instance methods
The following methods are available on instances of the Dictionary data type.
| Method name | Description |
|---|---|
| Add(TKey, TValue) | Adds the specified key and value to the dictionary. |
| ContainsKey(TKey) | Determines whether the Dictionary contains the specified key. |
| Count() | Gets the number of key/value pairs contained in the Dictionary. |
| Get(TKey, var TValue) | Gets the value associated with the specified key. |
| Get(TKey) | Gets the value associated with the specified key. |
| Keys() | Gets a collection containing the keys in the Dictionary. |
| Remove(TKey) | Removes the value with the specified key from the Dictionary. |
| Set(TKey, TValue) | Sets the value associated with the specified key. |
| Set(TKey, TValue, var TValue) | Sets the value associated with the specified key. |
| Values() | Gets a collection containing the values in the Dictionary. |
Remarks
Each addition to the dictionary consists of a value, and its associated key. Every key in a Dictionary must be unique. A key cannot be null, but a value can be, only when the value type is a reference type.
A Dictionary is a reference type, so assigning an instance of a dictionary to another variable or passing as a method parameter by value (for example without var), creates a second variable that reads/writes the same dictionary. It does not create a new dictionary.
To create a new dictionary that contains the same values as the original dictionary, you can do the following to perform a shallow copy:
trigger OnRun()
var
dict1: Dictionary of [Integer, Integer];
dict2: Dictionary of [Integer, Integer];
dictionaryKey: Integer;
begin
// ...
foreach dictionaryKey in dict1.Keys() do
dict2.Add(dictionaryKey, dict1.Get(dictionaryKey));
end;
The Dictionary data type does not support holding instantiated records. For this purpose, use temporary tables.
Warning
Previously in C/AL, one would have typically used an in-memory temporary table to create a key-value data structure, as shown in the code below. In AL you use the Dictionary Data Type instead.
IF KeyCacheRec.Get(‘Some Value’) THEN
Complete data stack execution;
Example
In the following example, the variable counter represents the Dictionary data type to store a value representing the number of occurrences for each character in the customerName. Using the Get method, you get the number of occurrences for the character at position i. If i returns false, it means there is no value associated with that character, so you add the value 1. If i returns true, it means the value already exists, so you add c + 1 to the value. The Add method adds the {key:value} pair to the Dictionary.
procedure CountCharactersInCustomerName(customerName: Text; counter: Dictionary of [Char, Integer])
var
i : Integer;
c : Integer;
begin
for i := 1 to StrLen(customerName) do
if counter.Get(customerName[i], c) then
counter.Set(customerName[i], c + 1)
else
counter.Add(customerName[i], 1);
end;