TransformationNodeBuilder.UnfoldColumn(String, String) Method

If a column is an array, transforms each element of this array to an individual record and changes the name of the column to the specified alias.

Namespace: DevExpress.DataAccess.DataFederation

Assembly: DevExpress.DataAccess.v25.1.dll

NuGet Package: DevExpress.DataAccess

Declaration

C#

public TransformationNodeBuilder UnfoldColumn(
    string columnName,
    string alias
)

VB.NET

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

Parameters

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

Returns

Type	Description
TransformationNodeBuilder	The result of the transformation query.

Example

The following example demonstrates how to unfold 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()
    .UnfoldColumn("Products", "CategoryProducts")
    .Build("ProductsUnfolded");

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().
    UnfoldColumn("Products", "CategoryProducts").
    Build("ProductsUnfolded")

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

The following schema is the result of the transformation:

"CategoryID": int
"CategoryProducts"
    "ProductName": string
    "UnitPrice": int