Before/After Read Event Handling

Show how to implement read events

Reads report.inp and skips all the records that are not detail records using a simple criteria

report.inp

-----------------------------------------------------
              XXX Enterprise
-----------------------------------------------------
10249   TOMSP  05071996      11.61
10250   HANAR  08071996      65.83
10251   VICTE  08071996       0.00
                                             Page 1
-----------------------------------------------------
                YYY Enterprise
-----------------------------------------------------
10269   TOMSP  05071996      11.61
10230   HANAR  08071996       0.00
10151   VICTE  08071996      41.34

Report layout.cs

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

    [FieldFixedLength(8)]
    public string CustomerID;

    [FieldFixedLength(8)]
    public DateTime OrderDate;

    [FieldFixedLength(11)]
    public decimal Freight;
}

RunEngine.cs

public override void Run()
{
    var engine = new FileHelperEngine<OrdersFixed>();
    engine.BeforeReadRecord += BeforeEvent;
    engine.AfterReadRecord += AfterEvent;

    var result = engine.ReadFile("report.inp");

    foreach (var value in result)
        Console.WriteLine("Customer: {0} Freight: {1}", value.CustomerID, value.Freight);

}

private void BeforeEvent(EngineBase engine, BeforeReadEventArgs<OrdersFixed> e)
{
    if (e.RecordLine.StartsWith(" ") ||
        e.RecordLine.StartsWith("-"))
        e.SkipThisRecord = true;

    //  Sometimes changing the record line can be useful, for example to correct for
    //  a bad data layout.  Here is an example of this, commented out for this example

    //if (e.RecordLine.StartsWith(" "))
    //   e.RecordLine = "Be careful!";
}


private void AfterEvent(EngineBase engine, AfterReadEventArgs<OrdersFixed> e)
{
    //  we want to drop all records with no freight
    if (e.Record.Freight == 0)
        e.SkipThisRecord = true;
}

Console

Customer:  TOMSP   Freight: 11,61
Customer:  HANAR   Freight: 65,83
Customer:  TOMSP   Freight: 11,61
Customer:  VICTE   Freight: 41,34

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

RunEngineLambda.cs

public void RunLambda()
{
    var engine = new FileHelperEngine<OrdersFixed>();
    engine.BeforeReadRecord += (eng, e) => {
        if (e.RecordLine.StartsWith (" ") ||
            e.RecordLine.StartsWith ("-"))
            e.SkipThisRecord = true;
    };
    engine.AfterReadRecord +=  (eng, e) => {
        if (e.Record.Freight == 0)
            e.SkipThisRecord = true;
    };

    var result = engine.ReadFile("report.inp");

    foreach (var value in result)
        Console.WriteLine("Customer: {0} Freight: {1}", value.CustomerID, value.Freight);

}