TransformationNodeBuilder.TransformColumn(String, String) Method

Transforms a column and specifies a new name for this column.

Namespace: DevExpress.DataAccess.DataFederation

Assembly: DevExpress.DataAccess.v25.1.dll

NuGet Package: DevExpress.DataAccess

Declaration

C#

public TransformationNodeBuilder TransformColumn(
    string columnName,
    string alias
)

VB.NET

Public Function TransformColumn(
    columnName As String,
    alias As String
) As TransformationNodeBuilder

Parameters

Name	Type	Description
columnName	String	The name of a column that should be transformed.
alias	String	A new column name.

Returns

Type	Description
TransformationNodeBuilder	The result of the transformation query.

Remarks

If a column is an array, the TransformColumn method unfolds this column and then flattens it. The Unfold operation transforms each element of the array into an individual record. The Flatten operation creates individual columns from the fields of these records.

Example

The following example demonstrates how to unfold and flatten a data source’s Products array and specify a new name for this array:

Show JSON Data

[
    {
        "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 source = new Source("Products", jsonDataSource);

var query = source
    .Transform()
    .TransformColumn("Products", "ProductsInfo")
    .Build("ProductsUnfoldedAndFlattened");

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

VB.NET

Imports DevExpress.DataAccess.DataFederation
Imports DevExpress.DataAccess.Json
' ...
Dim source = New Source("Products", jsonDataSource)

Dim query = source.
    Transform().
    TransformColumn("Products", "ProductsInfo").
    Build("ProductsUnfoldedAndFlattened")

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

The following schema is the result of the transformation:

"CategoryID": int
"ProductsInfo_ProductName": string
"ProductsInfo_UnitPrice": int