# Add dynapmic alias field if target field exist

**URL:** <https://discuss.elastic.co/t/add-dynapmic-alias-field-if-target-field-exist/309543>\
**Category:** Elasticsearch\
**Created:** [July 13, 2022, 2:15pm UTC](https://discuss.elastic.co/t/add-dynapmic-alias-field-if-target-field-exist/309543 "2022-07-13T14:15:59Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Denergym](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/denergym/32/108256_2.png) [@Denergym](https://discuss.elastic.co/u/Denergym)\
**Post date:** [July 13, 2022, 2:15pm UTC](https://discuss.elastic.co/t/add-dynapmic-alias-field-if-target-field-exist/309543/1 "2022-07-13T14:15:59Z")

</div>

Hi !

I need add alias field if target field exist or string.  
I do this with dynamic templates and aliases field

```auto
{
  "mappings": {
    "dynamic_templates": [
            {
        "add_alias_for_open": {
          "match_mapping_type": "string",
          "match":"Open2",
          "mapping": {
            "Open": {
                "type": "alias",
                "path": "Open2" 
            }
          }
        }
      }
    ]
  }
}'

```

But getting an error  
`"reason" : "unknown parameter [Open] on mapper [__dynamic__ alias_for_open] of type [null]"`

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [August 10, 2022, 2:16pm UTC](https://discuss.elastic.co/t/add-dynapmic-alias-field-if-target-field-exist/309543/2 "2022-08-10T14:16:22Z")

</div>

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