RegEx

Overview

The Regex plugin creates a single “union” table in a database from any files matching a regular expression (RegEx) by leveraging any of the flat file connectors (CSV, Excel, JSON, etc) as a base.

Create a RegEx job

Create a job using any of the flat file connectors:

Edit the job.

Rename the input’s use to base. base is how the Regex plugin knows which underlying flat file connector to use.

Add a new input use key with the value flatfile.iov2#RegexInput.

Remove the input source and add regex with the regular expression value.

Update the steps with the job's steps to these steps:

    "steps": [
        {
            "column": "__mtime__",
            "use": "mitto.iov2.steps#MaxTimestamp"
        },
        {
            "use": "mitto.iov2.steps.upsert#SetUpdatedAt"
        },
        {
            "transforms": [
                {
                    "use": "mitto.iov2.transform#ExtraColumnsTransform"
                },
                {
                    "use": "mitto.iov2.transform#ColumnsTransform"
                }
            ],
            "use": "mitto.iov2.steps#Input"
        },
        {
            "use": "mitto.iov2.steps#CreateTable"
        },
        {
            "use": "mitto.iov2.steps.upsert#CreateTempTable"
        },
        {
            "transforms": [
                {
                    "use": "mitto.iov2.transform#FlattenTransform"
                }
            ],
            "use": "mitto.iov2.steps#Output"
        },
        {
            "key": "__source__",
            "use": "mitto.iov2.steps.upsert#SyncTempTable"
        },
        {
            "use": "mitto.iov2.steps#CollectMeta"
        }
    ]

The Regex connector uses all the input parameters (e.g. delimiter, encoding, skip, etc) from the initial job's plugin.

Output table

The resulting database table has three additional columns:

__index__ - the index of each row in each separate file
__source__ - the source file the rows originate from
__mtime__ - the modified time of the source file

Upsert

Upsert is supported for RegEx jobs by using the __source__ as the primary key and __mtime__ as the last modified time.

Example

We have 3 CSV files we want to union together into a single database table.

Here's what the initial CSV files look like:

Here's the resulting database table for regex_1.csv after using the XSV plugin:

id	name	__index__
true	Justin	1

And here's the resulting database table after using the RegEx plugin:

id	name	__index__	__source__	__mtime__
3	Birdie	1	regex_3.csv	2020-02-19 17:30:20.680760
2	Bear	1	regex_2.csv	2020-02-19 17:30:20.628760
1	Justin	1	regex_1.csv	2020-02-19 17:30:20.572761

Here's the job config for the original XSV job:

{
    "input": {
        "delimiter": ",",
        "encoding": "ASCII",
        "includes_header": true,
        "source": "/var/mitto/data/regex_1.csv",
        "use": "xsv.iov2#XsvInput2"
    },
    "output": {
        "dbo": "postgresql://localhost/analytics",
        "schema": "test",
        "tablename": "regex_1",
        "use": "call:mitto.iov2.db#todb"
    },
    "sdl": {
        "columns": [
            {
                "__header__": "id",
                "__jpath__": "$.'id'",
                "name": "id",
                "type": "Boolean"
            },
            {
                "__header__": "name",
                "__jpath__": "$.'name'",
                "length": 30,
                "name": "name",
                "type": "String"
            }
        ],
        "name": "regex_1"
    },
    "steps": [
        {
            "transforms": [
                {
                    "use": "mitto.iov2.transform#ExtraColumnsTransform"
                },
                {
                    "use": "mitto.iov2.transform#ColumnsTransform"
                }
            ],
            "use": "mitto.iov2.steps#Input"
        },
        {
            "use": "mitto.iov2.steps#CreateTable"
        },
        {
            "transforms": [
                {
                    "use": "mitto.iov2.transform#FlattenTransform"
                }
            ],
            "use": "mitto.iov2.steps#Output"
        },
        {
            "use": "mitto.iov2.steps#CollectMeta"
        }
    ]
}

And here's the modified job config using the RegEx plugin:

{
    "input": {
        "delimiter": ",",
        "encoding": "ASCII",
        "includes_header": true,
        "regex": "^regex_.+\\.csv",
        "base": "xsv.iov2#XsvInput2",
        "use": "flatfile.iov2#RegexInput"
    },
    "output": {
        "dbo": "postgresql://localhost/analytics",
        "schema": "test",
        "tablename": "regex",
        "use": "call:mitto.iov2.db#todb"
    },
    "sdl": {
        "columns": [
            {
                "__header__": "id",
                "__jpath__": "$.'id'",
                "name": "id",
                "type": "Boolean"
            },
            {
                "__header__": "name",
                "__jpath__": "$.'name'",
                "length": 30,
                "name": "name",
                "type": "String"
            }
        ],
        "name": "regex_1"
    },
    "steps": [
        {
            "column": "__mtime__",
            "use": "mitto.iov2.steps#MaxTimestamp"
        },
        {
            "use": "mitto.iov2.steps.upsert#SetUpdatedAt"
        },
        {
            "transforms": [
                {
                    "use": "mitto.iov2.transform#ExtraColumnsTransform"
                },
                {
                    "use": "mitto.iov2.transform#ColumnsTransform"
                }
            ],
            "use": "mitto.iov2.steps#Input"
        },
        {
            "use": "mitto.iov2.steps#CreateTable"
        },
        {
            "use": "mitto.iov2.steps.upsert#CreateTempTable"
        },
        {
            "transforms": [
                {
                    "use": "mitto.iov2.transform#FlattenTransform"
                }
            ],
            "use": "mitto.iov2.steps#Output"
        },
        {
            "key": "__source__",
            "use": "mitto.iov2.steps.upsert#SyncTempTable"
        },
        {
            "use": "mitto.iov2.steps#CollectMeta"
        }
    ]
}

The input's use was renamed to base. A new use (for the RegEx plugin) was added to the input. The input's source was removed and regex was added. The output tablename was updated. The steps were completely replaced with the RegEx steps.

The input's regex for this particular job is ^regex_.+\\.csv$. We are looking for any files that start with (^) regex_, have any characters in the middle (.+), and end with ($) .csv.

This regex will feed in the 3 files we want to union:

regex_1.csv
regex_2.csv
regex_3.csv

Regular Expression syntax:

One helpful tool for testing regular expressions is RegExr.

One important thing to remember, because a job's config is stored in JSON, when using escape characters (\), you need to double escape them (\\).

Zuar Mitto

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