[[docs-update]]
== Update API

The update API allows to update a document based on a script provided.
The operation gets the document (collocated with the shard) from the
index, runs the script (with optional script language and parameters),
and index back the result (also allows to delete, or ignore the
operation). It uses versioning to make sure no updates have happened
during the "get" and "reindex".

Note, this operation still means full reindex of the document, it just
removes some network roundtrips and reduces chances of version conflicts
between the get and the index. The `_source` field needs to be enabled
for this feature to work.

For example, let's index a simple doc:

[source,js]
--------------------------------------------------
PUT test/type1/1
{
    "counter" : 1,
    "tags" : ["red"]
}
--------------------------------------------------
// CONSOLE

[float]
=== Scripted updates

Now, we can execute a script that would increment the counter:

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "script" : {
        "source": "ctx._source.counter += params.count",
        "lang": "painless",
        "params" : {
            "count" : 4
        }
    }
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

We can add a tag to the list of tags (note, if the tag exists, it
will still add it, since its a list):

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "script" : {
        "source": "ctx._source.tags.add(params.tag)",
        "lang": "painless",
        "params" : {
            "tag" : "blue"
        }
    }
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

In addition to `_source`, the following variables are available through
the `ctx` map: `_index`, `_type`, `_id`, `_version`, `_routing`
and `_now` (the current timestamp).

We can also add a new field to the document:

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "script" : "ctx._source.new_field = 'value_of_new_field'"
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

Or remove a field from the document:

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "script" : "ctx._source.remove('new_field')"
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

And, we can even change the operation that is executed.  This example deletes
the doc if the `tags` field contain `green`, otherwise it does nothing
(`noop`):

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "script" : {
        "source": "if (ctx._source.tags.contains(params.tag)) { ctx.op = 'delete' } else { ctx.op = 'none' }",
        "lang": "painless",
        "params" : {
            "tag" : "green"
        }
    }
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

[float]
=== Updates with a partial document

The update API also support passing a partial document,
which will be merged into the existing document (simple recursive merge,
inner merging of objects, replacing core "keys/values" and arrays). For
example:

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "doc" : {
        "name" : "new_name"
    }
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

If both `doc` and `script` are specified, then `doc` is ignored. Best is
to put your field pairs of the partial document in the script itself.

[float]
=== Detecting noop updates

If `doc` is specified its value is merged with the existing `_source`.
By default updates that don't change anything detect that they don't change anything and return "result": "noop" like this:

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "doc" : {
        "name" : "new_name"
    }
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

If `name` was `new_name` before the request was sent then the entire update
request is ignored. The `result` element in the response returns `noop` if
the request was ignored.

[source,js]
--------------------------------------------------
{
   "_shards": {
        "total": 0,
        "successful": 0,
        "failed": 0
   },
   "_index": "test",
   "_type": "type1",
   "_id": "1",
   "_version": 6,
   "result": noop
}
--------------------------------------------------
// TESTRESPONSE

You can disable this behavior by setting "detect_noop": false like this:

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "doc" : {
        "name" : "new_name"
    },
    "detect_noop": false
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

[[upserts]]
[float]
=== Upserts

If the document does not already exist, the contents of the `upsert` element
will be inserted as a new document.  If the document does exist, then the
`script` will be executed instead:

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "script" : {
        "source": "ctx._source.counter += params.count",
        "lang": "painless",
        "params" : {
            "count" : 4
        }
    },
    "upsert" : {
        "counter" : 1
    }
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

[float]
==== `scripted_upsert`

If you would like your script to run regardless of whether the document exists
or not -- i.e. the script handles initializing the document instead of the
`upsert` element -- then set `scripted_upsert` to `true`:

[source,js]
--------------------------------------------------
POST sessions/session/dh3sgudg8gsrgl/_update
{
    "scripted_upsert":true,
    "script" : {
        "id": "my_web_session_summariser",
        "params" : {
            "pageViewEvent" : {
                "url":"foo.com/bar",
                "response":404,
                "time":"2014-01-01 12:32"
            }
        }
    },
    "upsert" : {}
}
--------------------------------------------------
// CONSOLE
// TEST[s/"id": "my_web_session_summariser"/"source": "ctx._source.page_view_event = params.pageViewEvent"/]
// TEST[continued]

[float]
==== `doc_as_upsert`

Instead of sending a partial `doc` plus an `upsert` doc, setting
`doc_as_upsert` to `true` will use the contents of `doc` as the `upsert`
value:

[source,js]
--------------------------------------------------
POST test/type1/1/_update
{
    "doc" : {
        "name" : "new_name"
    },
    "doc_as_upsert" : true
}
--------------------------------------------------
// CONSOLE
// TEST[continued]

[float]
=== Parameters

The update operation supports the following query-string parameters:

[horizontal]
`retry_on_conflict`::

In between the get and indexing phases of the update, it is possible that
another process might have already updated the same document.  By default, the
update will fail with a version conflict exception.  The `retry_on_conflict`
parameter controls how many times to retry the update before finally throwing
an exception.

`routing`::

Routing is used to route the update request to the right shard and sets the
routing for the upsert request if the document being updated doesn't exist.
Can't be used to update the routing of an existing document.

`timeout`::

Timeout waiting for a shard to become available.

`wait_for_active_shards`::

The number of shard copies required to be active before proceeding with the update operation.
See <<index-wait-for-active-shards,here>> for details.

`refresh`::

Control when the changes made by this request are visible to search. See
<<docs-refresh>>.

`_source`::

Allows to control if and how the updated source should be returned in the response.
By default the updated source is not returned.
See <<search-request-source-filtering, `source filtering`>> for details.


`version` & `version_type`::

The update API uses the Elasticsearch's versioning support internally to make
sure the document doesn't change during the update. You can use the `version`
parameter to specify that the document should only be updated if its version
matches the one specified. By setting version type to `force` you can force
the new version of the document after update (use with care! with `force`
there is no guarantee the document didn't change).

[NOTE]
.The update API does not support external versioning
=====================================================

External versioning (version types `external` & `external_gte`) is not
supported by the update API as it would result in Elasticsearch version
numbers being out of sync with the external system.  Use the
<<docs-index_,`index` API>> instead.

=====================================================
