GanttControlNode.GetPredecessors() Method

Returns keys (see KeyFieldName) of the node’s predecessors.

Namespace: DevExpress.XtraGantt

Assembly: DevExpress.XtraGantt.v23.2.dll

NuGet Package: DevExpress.Win.Gantt

Declaration

C#

public object GetPredecessors()

VB.NET

Public Function GetPredecessors As Object

Returns

Type	Description
Object	An object that specifies keys of the task’s predecessors.

Remarks

Use the methods below to obtain a task’s predecessors. You can use a GanttControlNode object or Id property value to specify the task.

• GetPredecessorNodes(GanttControlNode), GetPredecessorNodes(Int32), and GetPredecessorNodes() - return an IEnumerable<T> collection of GanttControlNode objects that specify a task’s predecessors.

  If the control is bound to a data source, these methods are not in effect if you call them before the control is displayed onscreen because nodes are not created yet. You can call the ForceInitialize() method to force node creation.

• GetPredecessors(GanttControlNode), GetPredecessors(Int32), and GetPredecessors() - return keys (see KeyFieldName) of a task’s predecessors.

  If you use the DependencySource property to specify dependencies, the returned value is a List<T> of keys as they are specified in the data source (see PredecessorFieldName).

  If you use the DataSource property to specify dependencies, the returned value is an object as it is specified in the data source (see PredecessorsFieldName).

Use the methods below to obtain a task’s successors. You can use a GanttControlNode object or Id property value to specify the task.

• GetSuccessorNodes(GanttControlNode), GetSuccessorNodes(Int32), and GetSuccessorNodes() - return an IEnumerable<T> collection of GanttControlNode objects that specify a task’s successors.

  If the control is bound to a data source, these methods are not in effect if you call them before the control is displayed onscreen because nodes are not created yet. You can call the ForceInitialize() method to force node creation.

• GetSuccessors(GanttControlNode), GetSuccessors(Int32), and GetSuccessors() - return keys (see KeyFieldName) of a task’s successors.

  If you use the DependencySource property to specify dependencies, the returned value is a List<T> of keys as they are specified in the data source (see SuccessorFieldName).

  If you use the DataSource property to specify dependencies, you cannot get successors because this data source stores predecessors only.

Example

The example below shows how to get a task’s predecessors and successors. You can use the FindNodeByFieldValue(String, Object) method to retrieve a GanttControlNode object by the content in a specific field.

C#

using DevExpress.XtraGantt;
using System.Collections.Generic;

// The following methods return nodes that specify a task's predecessors and successors.
IEnumerable<GanttControlNode> predecessorNodes = 
    ganttControl1.GetPredecessorNodes(0);
IEnumerable<GanttControlNode> predecessorNodes1 = 
    ganttControl1.GetPredecessorNodes(ganttControl1.FindNodeByFieldValue("Text", "Task 2") as GanttControlNode);
IEnumerable<GanttControlNode> predecessorNodes2 = 
    (ganttControl1.FindNodeByFieldValue("Text", "Task 3") as GanttControlNode).GetPredecessorNodes();

IEnumerable<GanttControlNode> successorNodes = 
    ganttControl1.GetSuccessorNodes(0);
IEnumerable<GanttControlNode> successorNodes1 = 
    ganttControl1.GetSuccessorNodes(ganttControl1.FindNodeByFieldValue("Text", "Task 2") as GanttControlNode);
IEnumerable<GanttControlNode> successorNodes2 = 
    (ganttControl1.FindNodeByFieldValue("Text", "Task 3") as GanttControlNode).GetSuccessorNodes();

// The following methods return keys
// (as they are specified in the data source) of a task's predecessors and successors.
// If you use the DependencySource property to specify dependencies,
// the returned value is of List<object> type. Items in the collection are keys of the corresponding type.
List<object> predecessorKeyList = 
    ganttControl1.GetPredecessors(0) as List<object>;
List<object> predecessorsKeyList1 = 
    ganttControl1.GetPredecessors(ganttControl1.FindNodeByFieldValue("Text", "Task 2") as GanttControlNode) as List<object>;
List<object> predecessorsKeyList2 = 
    (ganttControl1.FindNodeByFieldValue("Text", "Task 3") as GanttControlNode).GetPredecessors() as List<object>;

List<object> successorKeyList = 
    ganttControl1.GetSuccessors(0) as List<object>;
List<object> successorsKeyList1 = 
    ganttControl1.GetSuccessors(ganttControl1.FindNodeByFieldValue("Text", "Task 2") as GanttControlNode) as List<object>;
List<object> successorsKeyList2 = 
    (ganttControl1.FindNodeByFieldValue("Text", "Task 3") as GanttControlNode).GetSuccessors() as List<object>;

// If you use the DataSource property to specify dependencies,
// the returned value is of the same type as in the data source.
// Note that you cannot get successors in this case
// since the data source stores predecessors only.
var predecessorKeys = 
    ganttControl1.GetPredecessors(0);
var predecessorsKeys1 = 
    ganttControl1.GetPredecessors(ganttControl1.FindNodeByFieldValue("Text", "Task 2") as GanttControlNode);
var predecessorsKeys2 = 
    (ganttControl1.FindNodeByFieldValue("Text", "Task 3") as GanttControlNode).GetPredecessors();

VB.NET

Imports DevExpress.XtraGantt
Imports System.Collections.Generic

' The following methods return nodes that specify a task's predecessors and successors.
Dim predecessorNodes = 
    ganttControl1.GetPredecessorNodes(0)
Dim predecessorNodes1 As IEnumerable(Of GanttControlNode) = 
    ganttControl1.GetPredecessorNodes(TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 2"), GanttControlNode))
Dim predecessorNodes2 As IEnumerable(Of GanttControlNode) = 
    TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 3"), GanttControlNode).GetPredecessorNodes()

Dim successorNodes = 
    ganttControl1.GetSuccessorNodes(0)
Dim successorNodes1 As IEnumerable(Of GanttControlNode) = 
    ganttControl1.GetSuccessorNodes(TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 2"), GanttControlNode))
Dim successorNodes2 As IEnumerable(Of GanttControlNode) = 
    TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 3"), GanttControlNode).GetSuccessorNodes()

' The following methods return keys
' (as they are specified in the data source) of a task's predecessors and successors.
' If you use the DependencySource property to specify dependencies,
' the returned value is of List<object> type. Items in the collection are keys of the corresponding type.
Dim predecessorKeyList As List(Of Object) = 
    TryCast(ganttControl1.GetPredecessors(0), List(Of Object))
Dim predecessorsKeyList1 As List(Of Object) = 
    TryCast(ganttControl1.GetPredecessors(TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 2"), GanttControlNode)), List(Of Object))
Dim predecessorsKeyList2 As List(Of Object) = 
    TryCast(TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 3"), GanttControlNode).GetPredecessors(), List(Of Object))

Dim successorKeyList As List(Of Object) = 
    TryCast(ganttControl1.GetSuccessors(0), List(Of Object))
Dim successorsKeyList1 As List(Of Object) = 
    TryCast(ganttControl1.GetSuccessors(TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 2"), GanttControlNode)), List(Of Object))
Dim successorsKeyList2 As List(Of Object) = 
    TryCast(TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 3"), GanttControlNode).GetSuccessors(), List(Of Object))

' If you use the DataSource property to specify dependencies,
' the returned value is of the same type as in the data source.
' Note that you cannot get successors in this case
' since the data source stores predecessors only.
Dim predecessorKeys = 
    ganttControl1.GetPredecessors(0)
Dim predecessorsKeys1 = 
    ganttControl1.GetPredecessors(TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 2"), GanttControlNode))
Dim predecessorsKeys2 = 
    TryCast(ganttControl1.FindNodeByFieldValue("Text", "Task 3"), GanttControlNode).GetPredecessors()