Item[string] Indexer

Overview

The Item[string] indexer allows you to get or set the current value of a data field of an observable data row by column name. This indexer provides convenient access to row values using array-like syntax.

Reading a value using the indexer returns null if the specified column does not exist or if the stored value is null.

Writing a value using the indexer updates the row value and may change the row DataRowState. If the row is in the Unchanged state, assigning a different value causes the framework to capture original values and mark the row as Modified.

Namespace and Assembly

Namespace: PocoDataSet.ObservableData
Assembly: PocoDataSet.ObservableData.dll

Usage Example

// 1. Create observable data set
IObservableDataSet observableDataSet = new ObservableDataSet();

// 2. Create Department observable table
IObservableDataTable departmentObservableDataTable = observableDataSet.AddNewTable("Department");
departmentObservableDataTable.AddColumn("Id", DataTypeNames.INT32);
departmentObservableDataTable.AddColumn("Name", DataTypeNames.STRING);

// 3. Add observable data row to Department observable table in Unchanged state by calling AcceptChanges method
IObservableDataRow departmentObservableDataRow1 = departmentObservableDataTable.AddNewRow();
departmentObservableDataRow1["Id"] = 1;
departmentObservableDataRow1["Name"] = "Marketing";
departmentObservableDataRow1.AcceptChanges();

// 4. Subscribe to all events of the observable data row
departmentObservableDataRow1.DataFieldValueChanged += DepartmentObservableDataRow1_DataFieldValueChanged;
departmentObservableDataRow1.PropertyChanged += DepartmentObservableDataRow1_PropertyChanged;
departmentObservableDataRow1.RowStateChanged += DepartmentObservableDataRow1_RowStateChanged;

// 5. Change any value of the observable data row and observe that all three events were raised and handled
departmentObservableDataRow1["Name"] = "Reception";

private void DepartmentObservableDataRow1_DataFieldValueChanged(object? sender, DataFieldValueChangedEventArgs e)
{
    // columnName = "Name"
    string columnName = e.ColumnName;
}

private void DepartmentObservableDataRow1_PropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
{
    // propertyName = "Name"
    string propertyName = e.PropertyName;
}

private void DepartmentObservableDataRow1_RowStateChanged(object? sender, RowStateChangedEventArgs e)
{
    // e.OldState is Unchanged
    DataRowState oldState = e.OldState;

    // e.NewState is Modified
    DataRowState newState = e.NewState;
}

 

Table of Content POCO DataSet API References ObservablePOCO DataSet Types ObservableDataRow Members

 

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Business Process Programming in .Net
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