Before/After Write Event Handling

Show how to implement write events

Input.txt

10249   TOMSP  05071996      11.61
10250   HANAR  08071996       0.00
10251   VICTE  08071996      41.34
10269   TOMSP  05071996      11.61
10230   HANAR  08071996      65.83
10151   VICTE  08071996      41.34

Report layout.cs

[FixedLengthRecord]
[IgnoreEmptyLines]
public class OrdersFixed
{
    [FieldFixedLength(7)]
    public int OrderID;

    [FieldFixedLength(8)]
    public string CustomerID;

    [FieldFixedLength(8)]
    public DateTime OrderDate;

    [FieldFixedLength(11)]
    public decimal Freight;
}

Run a record through engine using the write event to filter out unwanted details

RunEngine.cs

public override void Run()
{
    var engine = new FileHelperEngine<OrdersFixed>();

    var result = engine.ReadFile("Input.txt");

    //  add our filter logic.
    engine.BeforeWriteRecord += BeforeWriteEvent;
    engine.AfterWriteRecord += AfterWriteEvent;

    engine.WriteFile("output.txt", result);
}

private void BeforeWriteEvent(EngineBase engine, BeforeWriteEventArgs<OrdersFixed> e)
{
    //  We only want clients with large frieght values
    if (e.Record.Freight < 40)
        e.SkipThisRecord = true;
}

private void AfterWriteEvent(EngineBase engine, AfterWriteEventArgs<OrdersFixed> e)
{
    //  Hide a line
    if (e.Record.CustomerID.Trim() == "HANAR")
        e.RecordLine = "-- Insufficient Access";
}

output.txt

  10251 VICTE  08071996      41.34
-- Insufficient Access
  10151 VICTE  08071996      41.34

ImportantYou can use lambda expressions instead of event methods, for example:

RunEngineLambda.cs

public void RunLambda()
{
    var engine = new FileHelperEngine<OrdersFixed>();

    var result = engine.ReadFile("Input.txt");

    //  add our filter logic.
    engine.BeforeWriteRecord += (eng, e) => {
        if (e.Record.Freight < 40)
            e.SkipThisRecord = true;
    };
    engine.AfterWriteRecord += (eng, e) => {
        if (e.Record.CustomerID == "HANAR")
            e.RecordLine = "Insufficient Access";
    };

    engine.WriteFile("output.txt", result);
}