Legacy Product

Fusion 5.10
    Fusion 5.10

    Custom JavaScript Stages for Query Pipelines

    The JavaScript Query stage allows you to write custom processing logic using JavaScript to manipulate search requests and responses. The first time that the pipeline is run, Fusion compiles the JavaScript program into Java bytecode using the JDK’s JavaScript engine.

    The JavaScript Query stage allows you to run JavaScript functions over search requests and responses by manipulating variables called "request" and "response" which are Request objects and Response objects, respectively.

    Users who can create or modify code obtain access to the broader Fusion environment. This access can be used to create intentional or unintentional damage to Fusion.

    The JavaScript Engine Used by Fusion

    The JavaScript engine used by Fusion is the Nashorn engine from Oracle. See The Nashorn Java API for details.

    JavaScript Query Stage Global Variables

    JavaScript is a lightweight scripting language. The JavaScript in a JavaScript stage is standard ECMAScript. What a JavaScript program can do depends on the container in which it runs. For a JavaScript Query stage, the container is a Fusion query pipeline. The following global pipeline variables are available:

    Name Type Description

    request

    Request

    The Solr query information.

    response

    Response

    The Solr response information.

    ctx

    Context

    A map that stores miscellaneous data created by each stage of the pipeline.

    Use the ctx variable instead of the deprecated _context global variable.

    The ctx variable is used to:

    • Pass data from one stage to another

    • Store data that needs to be passed from one custom stage to a later custom stage

    The data can differ between stages:

    • If the previous stage changes the data

    • Based on the configuration of each stage

    If the data is modified in one stage, it may cause a later stage to function irregularly.

    collection

    String

    The name of the Fusion collection being indexed or queried.

    solrServer

    BufferingsolrServer

    The Solr server instance that manages the pipeline’s default Fusion collection. All indexing and query requests are done by calls to methods on this object. See solrClient for details.

    QueryRequestAndResponse

    QueryRequestAndResponse

    Used to create query pipeline requests and responses.

    JSONResponse

    JSONResponse

    Returns list of info as a string.
    See Custom JavaScript Query Stage Examples for more information.

    Syntax Variants

    JavaScript stages can be written using legacy syntax or function syntax. The key difference between these syntax variants is how the "global variables" are used. While using legacy syntax, these variables are used as global variables. With function syntax, however, these variables are passed as function parameters.

    Legacy Syntax

    Legacy syntax is used to perform very simple tasks.

    //do some work...
return doc;

    Function Syntax

    function(request,response) {
   request.addParam("foo", "bar");
}
    Function syntax is used for the examples in this document.

    Global variable logger

    The logs are output to the query service logs for custom query stages. Access the Log Viewer and filter on this service to view the information.

    See also