Some Readers allow to read data from the optional input port.
Input port reading is supported by the following Readers:
CSVReader
XLSDataReader
DBFDataReader
XMLExtract
XMLXPathReader
MultiLevelReader (Commercial Component)
Important | |
---|---|
Remember that port reading can also be used by DBExecute for receiving SQL commands. Query URL will be as follows: port:$0.fieldName:discrete. Also SQL command can be read from a file. Its name, including path, is then passed to DBExecute from input port and the Query URL attribute should be the following: port:$0.fieldName:source. |
If you connect the optional input port of any of these
Readers to an edge, you must also connect the
other side of this edge to some data source. To define the protocol for field mapping,
a field from where you want to read data must be set in the File URL
attribute of the Reader. The type of the FieldName
input field can only be
string
, byte
, or
cbyte
as defined in input edge metadata.
The protocol has the syntax
port:$0.FieldName[:processingType]
.
Here processingType
is optional and defines if the data
is processed as plain data or url addresses. It can be
source
, discrete
, or stream
. If
not set explicitly, discrete
is applied by
default.
To define the attributes of input port reading, URL File Dialog can be used.
When graph runs, data is read from the original data source (according to the metadata of the edge connected to the optional input port of the Readers) and received by the Reader through its optional input port. Each record is read independently of the other records. The specified field of each one is processed by the Reader according to the output metadata.
discrete
Each data record field from input port represents one particular data source.
source
Each data record field from input port represents an URL to be load in and parsed.
stream
All data fields from input port are concatenated and processed as one input file.
If the null
value of this field is met, it is replaced by the eof
.
Following data record fields are parsed as another input file in the same way, i.e., until the
null
value is met. See Output Port Writing
for more information about writing with stream
processing type.