JsonDataSource.Schema Property

Gets or sets the JsonDataSource‘s data schema.

Namespace: DevExpress.DataAccess.Json

Assembly: DevExpress.DataAccess.v18.2.dll

Declaration

C#

[Browsable(false)]
public JsonSchemaNode Schema { get; set; }

VB.NET

<Browsable(False)>
Public Property Schema As JsonSchemaNode

Property Value

Type	Description
JsonSchemaNode	An object associated with the root node of the data source.

Remarks

If you do not set the Schema property, it is set to the entire schema of the JSON data that the JsonSource property provides. Use the Schema property to set a custom schema where you can specify from which JSON nodes to retrieve data.

JSON schema consists of the root node and its child nodes. All schema nodes are the JsonSchemaNode objects that define a JSON object, array or property.

In the following code, the Customers node’s schema is defined and added to the data source’s root node.

root: {
    customers: [{
        CustomerID
        CompanyName
        ContactTitle
    }]
}

C#

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

            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))),
                new JsonSchemaNode(new JsonNode("Address", false, JsonNodeType.Property, typeof(string)))
            });

            root.AddChildren(customers);
            jsonDataSource.Schema = root;
            // Retrieve data from the JSON data source to the Report Designer's Field List
            jsonDataSource.Fill();
            return jsonDataSource;
        }

VB.NET

Imports DevExpress.DataAccess.Json
Imports DevExpress.XtraReports.UI
        ' ...
        Public Shared 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"))
            Dim root = New JsonSchemaNode()
            root.NodeType = JsonNodeType.Object

            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)))
            })

            root.AddChildren(customers)
            jsonDataSource.Schema = root
            ' Retrieve data from the JSON data source to the Report Designer's Field List
            jsonDataSource.Fill()
            Return jsonDataSource
        End Function

The following image demonstrates the result. A report’s field list displays only the selected properties.

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the Schema property.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

Create-a-Report-Bound-To-JsonDataSource/CS/Create-a-Report-Bound-to-JsonDataSource/Form1.cs#L72

root.AddChildren(customers);
jsonDataSource.Schema = root;
//Retrieve data from the JSON data source