Execute Script
- Leena Gopal
- Diane Miller (Deactivated)
- Ankur Parekh
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This Snap is Deprecated. See Script instead.
| Snap type: | Write | ||||||
|---|---|---|---|---|---|---|---|
| Description: | This Snap executes a script file using the ScriptEngine mechanism. The script is contained within a file, which can be located anywhere SnapLogic and the SnapLogic user has access to it. | ||||||
| Prerequisites: | [None] | ||||||
| Support and limitations: | Works in Ultra Tasks if you pass the original document to the 'write()' method for the output view. For example, in the JavaScript template, the body of the loop looks like: // Read the next document, wrap it in a map and write out the wrapper
var doc = this.input.next();
var wrapper = new java.util.HashMap();
wrapper.put("original", doc);
this.output.write(wrapper);
The last line should look like: this.output.write(doc, wrapper); The original document is needed so that lineage can be maintained. Breaking changes for Pipelines using the Script Snap (or the deprecated Execute Script Snap) with the Python engine To implement Python in the Script Snap we use Jython. We recently upgraded the Jython engine from version 2.7-b3 (a beta version from 2014) to the current version, 2.7.2 (March, 2020). The following are the resultant issues and workarounds that we are suggesting: | ||||||
| Account: | Accounts are not used with this Snap. | ||||||
| Views: |
| ||||||
Settings | |||||||
Label | Error rendering macro 'excerpt-include' : No link could be created for 'SPD:Snap Label'. | ||||||
| Scripting Language | Required. Language in which the script is provided. Options available include Python, Javascript, and Ruby. Default value: Javascript | ||||||
| Script File | Required. A script file that implements the ScriptHook interface. Example: slbd://transform.py Default value: [None] | ||||||
Examples
The ScriptHook interface that can be used by the script:
package com.snaplogic.scripting.language;
import java.util.Iterator;
/**
* ScriptHook is the interface that should be implemented as a callback mechanism for
* ExecuteScript Snap to call into the script.
*
*/
public interface ScriptHook {
/**
* Scripts should implement this method to provide application logic.
*/
void execute();
/**
* Input is interface that is used by the script to read input from the Snap's input view.
*/
public static interface Input extends Iterator<Object> {
}
/**
* Output is interface that is used by the script to send output data to the Snap output view.
*/
public static interface Output {
/**
* Write the data to the Snap output.
*
* @param data
*/
void write(Object data);
}
/**
* Error is interface that is used by the script to send error data to Snap error view.
*/
public static interface Error extends Output {
}
}
General Instructions for All Scripting Languages
The script author should declare a global variable named 'hook' (note that this variable name is case sensitive). Â
Â
Script engine makes 4 global variables available to the script - input, output, error and log.
- Variable 'input' is of type ScriptHook.Input defined above.
- Variable 'output' is of type ScriptHook.Output defined above.
- Variable 'error' is of type ScriptHook.Error defined above.
- Variable 'log' is of type org.slf4j.Logger.
Type defined in the schema maps to the Java class as shown below:
| Â Snap Type | Java class |
|---|---|
| Â NUMBERÂ Â | Â java.math.BigDecimal |
|  INTEGER |  java.math.BigInteger |
| Â STRING | Â java.lang.String |
|  DATETIME |  org.joda.time. DateTime  |
|  LOCALDATETIME |  org.joda.time. LocalDateTime |
|  BOOLEAN |  java.lang.Boolean |
|  DATE |  org.joda.time. LocalDate |
| Â TIME | Â org.joda.time.LocalTime |
|  BINARY |  java.lang.Byte |
|  TABLE |  java.util.List |
|  ANY |  java.lang.Object |
|  COMPOSITE |  java.util.Map |
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Objects written to the output view should be of Java types. This is required by some downstream Snaps, for example the Joiner Snap. To write out a Python map to the output view in a Python script, convert the map to a Java HashMap as follows:
import java.util
python_map = {}
self.output.write(java.util.HashMap(python_map))
Python
Script Snap uses Jython engine to execute the scripts written in Python.
from com.snaplogic.scripting.language import ScriptHook
from com.snaplogic.scripting.language.ScriptHook import *
class TransformScript(ScriptHook):
def __init__(self, input, output, error, log):
self.input = input
self.output = output
self.error = error
self.log = log
def execute(self):
self.log.info("Executing Transform script")
i = 0
while self.input.hasNext():
data = self.input.next().intValue()
if (i % 2 == 0):
self.error.write(data * 10);
else:
self.output.write(data * 10)
i = i + 1
self.log.info("Finished executing the Transform script")
hook = TransformScript(input, output, error, log)
Ruby
Script Snap uses JRuby engine to execute the scripts written in Ruby.
class MyScript
include com.snaplogic.scripting.language.ScriptHook
attr_reader :log, :input, :output, :error
def initialize(log, input, output, error)
@log = log
@input = input
@output = output
@error = error
@array = [java.lang.Integer.valueOf(1), java.lang.Integer.valueOf(2)]
end
def execute()
for element in @array
output.write(java.lang.Integer.valueOf(element))
end
end
end
$hook = MyScript.new($log, $input, $output, $error)
JavaScript
Script Snap uses Rhino engine to execute the scripts written in JavaScript.
script = {
execute : function() {
for (i = 0; i < data.length; i++) {
output.write(java.lang.Integer.valueOf(data[i]))
}
}
};
var data = [1, 2]
var hook = new com.snaplogic.scripting.language.ScriptHook(script)
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