[[painless-reindex-context]]
=== Reindex context

Use a Painless script in a {ref}/docs-reindex.html[reindex] operation to
add, modify, or delete fields within each document in an original index as its
reindexed into a target index.

*Variables*

`params` (`Map`, read-only)::
        User-defined parameters passed in as part of the query.

`ctx['op']` (`String`)::
        The name of the operation.

{ref}/mapping-routing-field.html[`ctx['_routing']`] (`String`)::
        The value used to select a shard for document storage.

{ref}/mapping-index-field.html[`ctx['_index']`] (`String`)::
        The name of the index.

{ref}/mapping-type-field.html[`ctx['_type']`] (`String`)::
        The type of document within an index.

{ref}/mapping-id-field.html[`ctx['_id']`] (`int`, read-only)::
        The unique document id.

`ctx['_version']` (`int`)::
        The current version of the document.

{ref}/mapping-source-field.html[`ctx['_source']`] (`Map`)::
        Contains extracted JSON in a `Map` and `List` structure for the fields
        existing in a stored document.

*Side Effects*

`ctx['op']`::
        Use the default of `index` to update a document. Set to `none` to
        specify no operation or `delete` to delete the current document from
        the index.

{ref}/mapping-routing-field.html[`ctx['_routing']`]::
        Modify this to change the routing value for the current document.

{ref}/mapping-index-field.html[`ctx['_index']`]::
        Modify this to change the destination index for the current document.

{ref}/mapping-type-field.html[`ctx['_type']`]::
        Modify this to change the type for the current document.

{ref}/mapping-id-field.html[`ctx['_id']`]::
        Modify this to change the id for the current document.

`ctx['_version']` (`int`)::
        Modify this to modify the version for the current document.

{ref}/mapping-source-field.html[`ctx['_source']`]::
        Modify the values in the `Map/List` structure to add, modify, or delete
        the fields of a document.

*Return*

`void`::
        No expected return value.

*API*

The standard <<painless-api-reference, Painless API>> is available.
