JsonSchemaNode() Constructor

Initializes a new instance of the JsonSchemaNode class.

Namespace: DevExpress.DataAccess.Json

Assembly: DevExpress.DataAccess.v19.1.dll

Declaration

C#

[Browsable(false)]
public JsonSchemaNode()

VB.NET

<Browsable(False)>
Public Sub New

Remarks

Use this constructor to create the data source schema‘s root node:

• The root node does not define a JSON object’s node.
• The root node has child nodes that define the JSON object’s nodes.

The following code sample demonstrates a root node.

C#

using DevExpress.DataAccess.Json;
using DevExpress.XtraReports.UI;
//...
private JsonDataSource CreateDataSourceFromWeb()
{
    var jsonDataSource = new JsonDataSource();
    //Specify the data source location
    jsonDataSource.JsonSource = new UriJsonSource(new Uri("http://northwind.servicestack.net/customers.json"));

    // Define the Customers node's scheme to retrieve only required child nodes and properties
    var customers = new JsonSchemaNode() {NodeType=JsonNodeType.Array, Name="Customers", Selected=true };
    customers.AddChildren(new[] {
        new JsonSchemaNode(new JsonNode("CustomerID", true, JsonNodeType.Property, typeof(string))) { DisplayName = "Customer ID" },
        new JsonSchemaNode() {
            Name =  "CompanyName",
            Selected = true,
            NodeType = JsonNodeType.Property,
            Type = typeof(string)
        },
        new JsonSchemaNode(new JsonNode("ContactTitle", true, JsonNodeType.Property, typeof(string))),
        //Set the JsonNode.Selected to false not to retrieve the Address field
        new JsonSchemaNode(new JsonNode("Address", false, JsonNodeType.Property, typeof(string)))
    });


    // Create a root schema node
    var root = new JsonSchemaNode();
    root.NodeType = JsonNodeType.Object;
    // Add the defined Customers schema node to the root node
    root.AddChildren(customers);
    // Specify the JsonDataSource's Scheme property to retrieve data only from the Customers node
    jsonDataSource.Schema = root;

    // Retrieve data from the JSON data source
    jsonDataSource.Fill();
    return jsonDataSource;
}

VB.NET

Imports DevExpress.DataAccess.Json
Imports DevExpress.XtraReports.UI
'...
Private Function CreateDataSourceFromWeb() As JsonDataSource
    Dim jsonDataSource = New JsonDataSource()
    'Specify the data source location
    jsonDataSource.JsonSource = New UriJsonSource(New Uri("http://northwind.servicestack.net/customers.json"))

    ' Define the Customers node's scheme to retrieve only required child nodes and properties
    Dim customers = New JsonSchemaNode() With {
        .NodeType=JsonNodeType.Array,
        .Name="Customers",
        .Selected=True
    }
    customers.AddChildren( {
        New JsonSchemaNode(New JsonNode("CustomerID", True, JsonNodeType.Property, GetType(String))) With {.DisplayName = "Customer ID"},
        New JsonSchemaNode() With {
            .Name = "CompanyName",
            .Selected = True,
            .NodeType = JsonNodeType.Property,
            .Type = GetType(String)
        },
        New JsonSchemaNode(New JsonNode("ContactTitle", True, JsonNodeType.Property, GetType(String))),
        New JsonSchemaNode(New JsonNode("Address", False, JsonNodeType.Property, GetType(String)))
    })
        'Set the JsonNode.Selected to false not to retrieve the Address field


    ' Create a root schema node
    Dim root = New JsonSchemaNode()
    root.NodeType = JsonNodeType.Object
    ' Add the defined Customers schema node to the root node
    root.AddChildren(customers)
    ' Specify the JsonDataSource's Scheme property to retrieve data only from the Customers node
    jsonDataSource.Schema = root

    ' Retrieve data from the JSON data source
    jsonDataSource.Fill()
    Return jsonDataSource
End Function