OpenSearch/docs/reference/mapping/dynamic/templates.asciidoc

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[[dynamic-templates]]
=== Dynamic templates
Dynamic templates allow you to define custom mappings that can be applied to
dynamically added fields based on:
* the <<dynamic-mapping,datatype>> detected by Elasticsearch, with <<match-mapping-type,`match_mapping_type`>>.
* the name of the field, with <<match-unmatch,`match` and `unmatch`>> or <<match-pattern,`match_pattern`>>.
* the full dotted path to the field, with <<path-match-unmatch,`path_match` and `path_unmatch`>>.
The original field name `{name}` and the detected datatype
`{dynamic_type`} <<template-variables,template variables>> can be used in
the mapping specification as placeholders.
IMPORTANT: Dynamic field mappings are only added when a field contains a
concrete value -- not `null` or an empty array. This means that if the
`null_value` option is used in a `dynamic_template`, it will only be applied
after the first document with a concrete value for the field has been
indexed.
Dynamic templates are specified as an array of named objects:
[source,js]
--------------------------------------------------
"dynamic_templates": [
{
"my_template_name": { <1>
... match conditions ... <2>
"mapping": { ... } <3>
}
},
...
]
--------------------------------------------------
<1> The template name can be any string value.
<2> The match conditions can include any of : `match_mapping_type`, `match`, `match_pattern`, `unmatch`, `match_path`, `unmatch_path`.
<3> The mapping that the matched field should use.
Templates are processed in order -- the first matching template wins. New
templates can be appended to the end of the list with the
<<indices-put-mapping,PUT mapping>> API. If a new template has the same
name as an existing template, it will replace the old version.
[[match-mapping-type]]
==== `match_mapping_type`
The `match_mapping_type` matches on the datatype detected by
<<dynamic-field-mapping,dynamic field mapping>>, in other words, the datatype
that Elasticsearch thinks the field should have. Only the following datatypes
can be automatically detected: `boolean`, `date`, `double`, `long`, `object`,
`string`. It also accepts `*` to match all datatypes.
For example, if we wanted to map all integer fields as `integer` instead of
`long`, and all `string` fields as both `analyzed` and `not_analyzed`, we
could use the following template:
[source,js]
--------------------------------------------------
PUT my_index
{
"mappings": {
"my_type": {
"dynamic_templates": [
{
"integers": {
"match_mapping_type": "long",
"mapping": {
"type": "integer"
}
}
},
{
"strings": {
"match_mapping_type": "string",
"mapping": {
"type": "string",
"fields": {
"raw": {
"type": "string",
"index": "not_analyzed",
"ignore_above": 256
}
}
}
}
}
]
}
}
}
PUT my_index/my_type/1
{
"my_integer": 5, <1>
"my_string": "Some string" <2>
}
--------------------------------------------------
// AUTOSENSE
<1> The `my_integer` field is mapped as an `integer`.
<2> The `my_string` field is mapped as an analyzed `string`, with a `not_analyzed` <<multi-fields,multi field>>.
[[match-unmatch]]
==== `match` and `unmatch`
The `match` parameter uses a pattern to match on the fieldname, while
`unmatch` uses a pattern to exclude fields matched by `match`.
The following example matches all `string` fields whose name starts with
`long_` (except for those which end with `_text`) and maps them as `long`
fields:
[source,js]
--------------------------------------------------
PUT my_index
{
"mappings": {
"my_type": {
"dynamic_templates": [
{
"longs_as_strings": {
"match_mapping_type": "string",
"match": "long_*",
"unmatch": "*_text",
"mapping": {
"type": "long"
}
}
}
]
}
}
}
PUT my_index/my_type/1
{
"long_num": "5", <1>
"long_text": "foo" <2>
}
--------------------------------------------------
// AUTOSENSE
<1> The `long_num` field is mapped as a `long`.
<2> The `long_text` field uses the default `string` mapping.
[[match-pattern]]
==== `match_pattern`
The `match_pattern` parameter adjusts the behavior of the `match` parameter
such that it supports full Java regular expression matching on the field name
instead of simple wildcards, for instance:
[source,js]
--------------------------------------------------
"match_pattern": "regex",
"match": "^profit_\d+$"
--------------------------------------------------
[[path-match-unmatch]]
==== `path_match` and `path_unmatch`
The `path_match` and `path_unmatch` parameters work in the same way as `match`
and `unmatch`, but operate on the full dotted path to the field, not just the
final name, e.g. `some_object.*.some_field`.
This example copies the values of any fields in the `name` object to the
top-level `full_name` field, except for the `middle` field:
[source,js]
--------------------------------------------------
PUT my_index
{
"mappings": {
"my_type": {
"dynamic_templates": [
{
"full_name": {
"path_match": "name.*",
"path_unmatch": "*.middle",
"mapping": {
"type": "string",
"copy_to": "full_name"
}
}
}
]
}
}
}
PUT my_index/my_type/1
{
"name": {
"first": "Alice",
"middle": "Mary",
"last": "White"
}
}
--------------------------------------------------
// AUTOSENSE
[[template-variables]]
==== `{name}` and `{dynamic_type}`
The `{name}` and `{dynamic_type}` placeholders are replaced in the `mapping`
with the field name and detected dynamic type. The following example sets all
string fields to use an <<analyzer,`analyzer`>> with the same name as the
field, and disables <<doc-values,`doc_values`>> for all non-string fields:
[source,js]
--------------------------------------------------
PUT my_index
{
"mappings": {
"my_type": {
"dynamic_templates": [
{
"named_analyzers": {
"match_mapping_type": "string",
"match": "*",
"mapping": {
"type": "string",
"analyzer": "{name}"
}
}
},
{
"no_doc_values": {
"match_mapping_type":"*",
"mapping": {
"type": "{dynamic_type}",
"doc_values": false
}
}
}
]
}
}
}
PUT my_index/my_type/1
{
"english": "Some English text", <1>
"count": 5 <2>
}
--------------------------------------------------
// AUTOSENSE
<1> The `english` field is mapped as a `string` field with the `english` analyzer.
<2> The `count` field is mapped as a `long` field with `doc_values` disabled
[[override-default-template]]
=== Override default template
You can override the default mappings for all indices and all types
by specifying a `_default_` type mapping in an index template
which matches all indices.
For example, to disable the `_all` field by default for all types in all
new indices, you could create the following index template:
[source,js]
--------------------------------------------------
PUT _template/disable_all_field
{
"disable_all_field": {
"order": 0,
"template": "*", <1>
"mappings": {
"_default_": { <2>
"_all": { <3>
"enabled": false
}
}
}
}
}
--------------------------------------------------
// AUTOSENSE
<1> Applies the mappings to an `index` which matches the pattern `*`, in other
words, all new indices.
<2> Defines the `_default_` type mapping types within the index.
<3> Disables the `_all` field by default.