Mapping Rule Filters

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Example

A mapping rule filter consists of a JavaScript expression which evaluates each row of input data. The column values from the row are available in the columns["<column_name>"] object.

During a migration job, Relational Migrator evaluates the expression for each row:

If the return value is true then the row is included in the migrated data.
If the return value is false then the row is excluded.
If the return value is not either, the row is excluded and an error is logged during migration.

Example

Below is an example of input documents and mapping rule JavaScript expressions that filter the data.

Filter Based on Field Value

The following example filters a document based on a single field value.

Relational input:

customer_id	company_name	address	city	postal_code	country	phone
ALFKI	Alfreds Futterkiste	Obere Str. 57	Berlin	12209	Germany	030-0074321
ANATR	Ana Trujillo Emparedados y helados	Avda. de la Constitución 2222	México D.F.	05021	Mexico	5-555-4729
ANTON	Antonio Moreno Taquería	Mataderos 2312	México D.F.	05023	Mexico	5-555-3932

Filter Expression:

columns["country"] == "Mexico"

MongoDB output:

[
    {
        "customerId": "ANATR",
        "address": "Avda. de la Constitución 2222",
        "city": "México D.F.",
        "companyName": "Ana Trujillo Emparedados y helados",
        "country": "Mexico",
        "phone": "5-555-4729",
        "postalCode": "05021",
    },
    {
        "customerId": "ANTON",
        "address": "Mataderos  2312",
        "city": "México D.F.",
        "companyName": "Antonio Moreno Taquería",
        "country": "Mexico",
        "phone": "5-555-3932",
        "postalCode": "05023",
    }
]

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