selection

This processor encapsulates the selection phase of ts-transforms.

To use this processor, it is required to use the selection processor as this works by using the metadata that is set in the selection processor. It also requires a file containing all transform rules that is will be preforming and any necessary plugins that those rules require to operate.

The full functionality of ts-transforms is encapsulated in the transform processor.

You would only want to use this processor instead of the fully functional transform processor if you wanted to inject a custom operation between each phase, or to capture the analytics of the records between each phase.

Usage

Example of the rules and plugins to run the selection phase

Below contains an example of the transform rules, plugins and configurations to perform the selection phase. Note that the post-process and output phases of ts-transforms are not executed.

Example Job

{
    "name" : "testing",
    "workers" : 1,
    "slicers" : 1,
    "lifecycle" : "once",
    "assets" : [
        "standard"
    ],
    "operations" : [
        {
            "_op": "test-reader"
        },
        {
            "_op": "selection",
            "plugins": ["someAssetId:plugins"],
            "rules": ["someAssetId:transformRules.txt"],
            "type_config": {
                "some": "string",
                "field": "string",
                "field2": "string",
                "date": "date",
                "location": "geo-point"
            },
            "variables": {
                "foo": "data"
            }
        }
    ]
}

Example rules located at someAssetId:transformRules.txt

{ "selector": "some: $foo", "source_field": "field", "target_field": "interm1", "tag": "someTag", "output": false }
{ "selector": "some: $foo", "source_field": "field2", "target_field": "interm2", "tag": "someTag", "output": false }
{ "follow": "someTag", "post_process": "join", "target_field": "final", "delimiter": " " }

{ "source_field": "otherField", "target_field": "lastField", "other_match_required": true }
{ "source_field": "_key", "target_field": "id", "other_match_required": true, "tag": "numberMe" }
{ "follow": "numberMe", "post_process": "number" }

{ "selector": "location: geoBox( top_left: '33.906320, -112.758421' bottom_right: '32.813646,-111.058902')", "source_field": "location", "target_field": "loc" }

{ "selector": "date:[2019-04-16T20:14:44.304Z TO *] AND bytes:>=1000000", "source_field": "date", "target_field": "last_seen", "tag": "tagOp" }
{ "follow": "tagOp", "post_process": "tag" }

Example plugin used by rules above located at someAssetId:plugins

import { DataEntity } from '@terascope/job-components';

class Tag {
    static cardinality = 'one-to-one';

    constructor(operationConfig) {
        this.operationConfig = operationConfig;
    }

    run(doc: DataEntity) {
        doc.wasTagged = true;
        return doc;
    }
}

export default class Plugin {
    init() {
        return {
            tag: Tag,
        };
    }
}

Example of the data and the expected results of the selection phase, the metadata is what is set by the selection processor

const data = [
    new DataEntity({ some: 'data' }),
    new DataEntity({ some: 'other' }),
    new DataEntity({ location: '33.435967,-111.867710', zip: 94302 })
];

const results = await processor.run(data);

results === [
   { some: 'data' },
   { location: '33.435967,-111.867710', zip: 94302 }
];

Parameters

Configuration	Description	Type	Notes
_op	Name of operation, it must reflect the exact name of the file	String	required
rules	an array of strings that are the locations where rule files. must be specified in "assetName:path" format	String[]	required
plugins	an array of strings that are the locations where plugins reside. must be specified in "assetName:modulePath" format	Object[]	optional, defaults to []
type_config	a schema for the data being consumed. Set the keys to your data field names, with values set to this enum	Object	optional
variables	An object containing any variables for the xlucene rules	Object	optional