QueryBuildingExtensions.Transform(IJoinNode) Method

Creates a TransformationNodeBuilder object that allows you to apply transformations to a node created after the Join, Select, Union, or Union All operations.

Namespace: DevExpress.DataAccess.DataFederation

Assembly: DevExpress.DataAccess.v24.2.dll

Declaration

C#

public static TransformationNodeBuilder Transform(
    this IJoinNode root
)

VB.NET

<ExtensionAttribute>
Public Shared Function Transform(
    root As IJoinNode
) As TransformationNodeBuilder

Parameters

Name	Type	Description
root	IJoinNode	A node created after the Join, Select, Union, or Union All operations.

Returns

Type	Description
TransformationNodeBuilder	An object that allows you to apply transformation operations.

Example

The following example demonstrates how to unfold and flatten the Products array of two data sources and unite data from these sources.

Show JSON Data (Products1.json)

[
    {
        "CategoryID": 1,
        "Products":
        [
            {
                "ProductName": "Chai",
                "UnitPrice": 18
            },
            {
                "ProductName": "Chang",
                "UnitPrice": 19
            }
        ]
    },
    {
        "CategoryID": 2,
        "Products":
        [
            {
                "ProductName": "Ikura",
                "UnitPrice": 31
            },
            {
                "ProductName": "Konbu",
                "UnitPrice": 6
            }
        ]
    }
]

Show JSON Data (Products2.json)

[
    {
        "CategoryID": 1,
        "Products":
        [
            {
                "ProductName": "Chai",
                "UnitPrice": 18
            },
            {
                "ProductName": "Chang",
                "UnitPrice": 19
            }
        ]
    },
    {
        "CategoryID": 2,
        "Products":
        [
            {
                "ProductName": "Ikura",
                "UnitPrice": 31
            },
            {
                "ProductName": "Konbu",
                "UnitPrice": 6
            }
        ]
    }
]

C#

using DevExpress.DataAccess.DataFederation;
using DevExpress.DataAccess.Json;
// ...
var source1 = new Source("Products1", jsonDataSource1);
var source2 = new Source("Products2", jsonDataSource2);

var query = source1
    .From()
    .Select("Products")
    .Build()
    .Union(source2
        .From()
        .Select("Products")
        .Build())
    .Build()
    .Transform()
    .TransformColumn("Products")
    .Build("ProductsUnited");

var federation = new FederationDataSource() {
    Queries = { query }
};

VB.NET

Imports DevExpress.DataAccess.DataFederation
Imports DevExpress.DataAccess.Json
' ...
Dim source1 = New Source("Products1", jsonDataSource1)
Dim source2 = New Source("Products2", jsonDataSource2)

Dim query = source1.
    From().
    Select("Products").
    Build().
    Union(source2.From().
        Select("Products").
        Build()).
    Build().
    Transform().
    TransformColumn("Products").
    Build("ProductsUnited")

Dim federation = New FederationDataSource()
federation.Queries.Add(query)

The following schema is the result of the transformation:

"Products_ProductName": string
"Products_UnitPrice" : string