Buffer.SetString Not Writing Values!

Hello all,

I'm writing a custom component similar to the "Derived Column" transformation, in which a value of some input column is "decoded" into an output column.

Here's the code:





Code Snippet

public override void ProcessInput(int inputID, PipelineBuffer buffer){

//TODO

setupTraceListener();

IDTSOutput90 outp = ComponentMetaData.OutputCollection["DecodeOutput"];

int outId = outp.ID;

int errorOut = -1;

IDTSInput90 inp = ComponentMetaData.InputCollection.GetObjectByID(inputID);
if( ComponentMetaData.OutputCollection.Count > 1){errorOut = ComponentMetaData.OutputCollection["DecodeErrors"].ID;

}

string sourceValue;

if(!buffer.EndOfRowset){
while(buffer.NextRow()){

if(!buffer.IsNull(inputColumnBufferIndex)){

switch(inp.InputColumnCollection[0].DataType){

case DataType.DT_WSTR:

sourceValue = buffer.GetString(this.inputColumnBufferIndex);

break;

case DataType.DT_I4:

sourceValue = buffer.GetInt32(this.inputColumnBufferIndex).ToString();

break;

default: throw new Exception("Invalid Data Type!");

}

sourceValue = sourceValue.Trim();

try{

object decodedValueObj = this.mappings[sourceValue];

if(decodedValueObj == null){

throw new Exception("No mapping!");

}

string decodedValue = decodedValueObj.ToString();

switch(outp.OutputColumnCollection[0].DataType){

case DataType.DT_WSTR:

buffer.SetString(this.outputColumnBufferIndex, decodedValue);

break;

case DataType.DT_I4:

buffer.SetInt32(this.outputColumnBufferIndex, int.Parse(decodedValue));

break;

default:

throw new IOException("Invalid Data Type!");

}

buffer.DirectRow(outId);

}catch(IOException fake){

throw fake;

}catch(Exception e){

redirectOrFail(inp, errorOut, outId, buffer, e);

}

}else{

redirectOrFail(inp,errorOut,outId,buffer,new Exception("Null values cannot be mapped"));

}

}

}

}





mappings is a hash map filled in PreExecute by accessing a database, outputColumnBufferIndex is calculated like this:




Code Snippet
IDTSInput90 input = ComponentMetaData.InputCollection[0];
IDTSOutput90 output = ComponentMetaData.OutputCollection["DecodeOutput"];
IDTSInputColumn90 inputColumn = input.InputColumnCollection[0];
IDTSOutputColumn90 outputColumn = output.OutputColumnCollection[0];
this.inputColumnBufferIndex =
BufferManager.FindColumnByLineageID(input.Buffer, inputColumn.LineageID);
this.outputColumnBufferIndex =
BufferManager.FindColumnByLineageID(input.Buffer, outputColumn.LineageID);






I've highlighted the parts that interest me, I've been testing the component thoroughly and it is getting the input data and mappings right, but it won't write the Decoded value to the given column and leaves it empty, even though the decodedValue variable is not null.

I'm guessing theres a problem when I call buffer.SetString() but I haven't the slightest idea of what that could be.

Any help would be greatly appreciated!