07 March 2024

Collection Index

An index can be defined on a Collection property (such as List). Setting such an index means that each of the Collection's items is indexed.

Setting an index on a Collection is done using the SpaceIndex.Path attribute where a Collection property should be followed by "[*]".

The following example shows how to define an index on a List of Integers:

[SpaceClass]
public class CollectionIndexingExample
{
  private Integer id;
  private List<int> numbers;

  // Getter and setter methods...

  // This means that each Integer in the List is indexed.
  [SpaceIndex(Path = "[*]")]
  [SpaceProperty (StorageType=StorageType.Object)]
  public List<string> myList { get; set; }
  public List&lt;int&gt; Numbers { get; set; }

}

The following query shows how to take advantage of the defined index:

SqlQuery<CollectionIndexingExample> sqlQuery =
    new SqlQuery<CollectionIndexingExample>("Numbers[*] = 30");
CollectionIndexingExample[] result = spaceProxy.ReadMultiple(sqlQuery);

Nested Property within a Collection

Its also possible to index a nested property within a collection.

The following example shows how to define an index on a Book.id property, which resides in a Collection property in Author:

[SpaceClass]
public class Author
{
  // Properties...

  // This means that each Book.Id in the Collection is indexed.
  [SpaceIndex(Path = "[*].Id")]
  [SpaceProperty(StorageType = StorageType.Document)]
  public List<Book> Books{ get; set; }
}

public class Book
{
  // Properties...

  public int? Id{ get; set; }
}

The following query shows how to take advantage of the defined index:

SqlQuery<Author> sqlQuery = new SqlQuery<Author>("Books[*].Id = 57");
Author result = spaceProxy.Read(sqlQuery);

Setting an index on a Collection within a nested property is also accepted:

[SpaceClass]
public class Employee
{
  // Properties...

  [SpaceIndex(Path = "PhoneNumbers[*]")]
  [SpaceProperty(StorageType = StorageType.Document)]
  public Information Information{ get; set; }
}

public class Information
{
  // Properties...
  public List<String> PhoneNumbers{ get; set; }
}