Row Generator
Description
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Pipeline source: this transform can start without incoming hops. Hop Gui refuses hops into it. |
To use fields, you must have a data row. A data row will automatically be generated by some transforms like a table input (if you ran the preview). If no data row exists add a “Generate rows” transform to create a row(s) in order to use fields or print variables or parameters etc.
The Generate rows transform outputs a specified number of rows that are empty or have a set of hard-coded fields. By default, the rows are empty; however they can contain a number of static fields.
This transform is used primarily for testing purposes. It may be useful for generating a fixed number of rows, for example, you want exactly 12 rows for 12 months.
Sometimes you may use Generate Rows to generate one row that is an initiating point for your pipeline. For example, you might generate one row that contains two or three field values that you might use to parameterize your SQL and then generate the real rows.
Examples: * To generate a row of sample data, add two action items to a pipeline. Add a Generate rows transform connected to Add constants. In Add constants, you can add fields to generate. In Generate rows, you can limit the number of rows. * To loop through 100 rows you could use a Generate rows and an “Add sequence” Action to the pipeline and connect them on a pipeline.
Options
| Option | Description |
|---|---|
Transform Name |
Name of the transform this name has to be unique in a single pipeline |
Limit |
Sets the maximum number of rows you want to generate |
Fields |
Structure and constant values of the generated rows (optional). See Fields. |
Never stop generating rows |
This option is intended for real-time use cases where you never want to stop the running pipeline. The output of this transform is then used to drive recurring tasks like polling from a file, queue, database, … |
Interval in ms |
The interval between generated rows in milliseconds. |
Current row time field name |
The *optional *field name for the Date field containing the time when the current row was generated |
Previous row time field name |
The *optional *field name for the Date field containing the time when the previous row was generated |
Fields
Each row in the Fields table defines one output field. Every generated pipeline row carries the same constants.
The columns below appear on many field tables. They are field metadata: they control how Hop converts a string to a typed value, and how a typed value is written back to a string. They do not change the value stored in a database.
| Column | Description |
|---|---|
Format / Conversion mask |
Number, date or Boolean pattern used to parse and print the value. See Formatting numbers and dates. |
Length |
String: maximum characters.
Number / BigNumber: significant digits.
Integer: display width (leading zeros when writing).
Date: length of the printed string (for example |
Precision |
Decimal digits after the radix for Number and BigNumber. Not used for String, Date or Boolean. |
Decimal |
Character that separates the integer and fractional parts.
|
Group / Grouping |
Thousands grouping symbol.
|
Currency |
Optional currency symbol used when the format mask contains a currency sign ( |
Value |
A single constant, entered as a string and parsed with Type, Format, Decimal, Group and Currency. Not a comma-separated list of values. Use Data Grid when you need several different rows. |
Set empty string? |
When the constant is empty, emit an empty string ( |
| Column | Description |
|---|---|
Name |
Name of the generated field. |
Type |
Hop data type. The Value string is parsed into this type. See Data types. |
Value is a single constant, not a comma-separated list.
1,2,3 is one string (or a parse error), not three rows.
Group is the thousands separator (, in 1,000.00), not a row group.
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To emit several different rows of sample data, use Data Grid instead.