# How can I change an existing field type using Python? **URL:** \ **Category:** Elasticsearch\ **Created:** [November 16, 2018, 3:37am UTC](https://discuss.elastic.co/t/how-can-i-change-an-existing-field-type-using-python/156968 "2018-11-16T03:37:37Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![seanthegeek](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/seanthegeek/32/33421_2.png) [@seanthegeek](https://discuss.elastic.co/u/seanthegeek)\ **Post date:** [November 16, 2018, 3:37am UTC](https://discuss.elastic.co/t/how-can-i-change-an-existing-field-type-using-python/156968/1 "2018-11-16T03:37:38Z")
Hi Everyone, I have an open source project that uses Elasticsearch and Kibana to visualize DMARC data for almost a year now. > **[GitHub - domainaware/parsedmarc: A Python package and CLI for parsing...](https://github.com/domainaware/parsedmarc)** > > A Python package and CLI for parsing aggregate and forensic DMARC reports - GitHub - domainaware/parsedmarc: A Python package and CLI for parsing aggregate and forensic DMARC reports Just recently, a user found a bug where I mapped a field to a `long` when it should be `text` (it went unnoticed for so long because the value is _almost_ always `"0"`. > > > Fresh Install, Ubuntu 18.04.1 > > Python 3.6.6 > parsedmarc 4.3.8 > elasticsearch: …6.4.3 > > Reports seem to grab okay via IMAP, but fail when trying to import to elasticsearch. > > Traceback (most recent call last): > File "/usr/local/bin/parsedmarc", line 11, in \ > sys.exit(\_main()) > File "/opt/venvs/parsedmarc/site-packages/parsedmarc/cli.py", line 333, in \_main > process\_reports(results) > File "/opt/venvs/parsedmarc/site-packages/parsedmarc/cli.py", line 42, in process\_reports > report, index=es\_aggregate\_index) > File "/opt/venvs/parsedmarc/site-packages/parsedmarc/elastic.py", line 292, in save\_aggregate\_report\_to\_elasticsearch > agg\_doc.save() > File "/opt/venvs/parsedmarc/site-packages/parsedmarc/elastic.py", line 88, in save > return super().save(\*\* kwargs) > File "/opt/venvs/parsedmarc/site-packages/elasticsearch\_dsl/document.py", line 383, in save > self.full\_clean() > File "/opt/venvs/parsedmarc/site-packages/elasticsearch\_dsl/utils.py", line 444, in full\_clean > self.clean\_fields() > File "/opt/venvs/parsedmarc/site-packages/elasticsearch\_dsl/utils.py", line 430, in clean\_fields > data = field.clean(data) > File "/opt/venvs/parsedmarc/site-packages/elasticsearch\_dsl/field.py", line 207, in clean > data.full\_clean() > File "/opt/venvs/parsedmarc/site-packages/elasticsearch\_dsl/utils.py", line 444, in full\_clean > self.clean\_fields() > File "/opt/venvs/parsedmarc/site-packages/elasticsearch\_dsl/utils.py", line 430, in clean\_fields > data = field.clean(data) > File "/opt/venvs/parsedmarc/site-packages/elasticsearch\_dsl/field.py", line 95, in clean > data = self.deserialize(data) > File "/opt/venvs/parsedmarc/site-packages/elasticsearch\_dsl/field.py", line 91, in deserialize > return self.\_deserialize(data) > File "/opt/venvs/parsedmarc/site-packages/elasticsearch\_dsl/field.py", line 314, in \_deserialize > return int(data) > ValueError: invalid literal for int() with base 10: '0:1:d:s' So now I need to find a way to correct this field type in every user's index and Kibana index pattern, preferably in a fully automated way. My attempt at doing this failed, but hopefully it gives you a good idea of what I'm going for: ```python def migrate_indexes(aggregate_indexes=None, forensic_indexes=None): """ Updates index mappings Args: aggregate_indexes (list): A list of aggregate index names forensic_indexes (list): A list of forensic index names """ if aggregate_indexes is None: aggregate_indexes = [] if forensic_indexes is None: forensic_indexes = [] for aggregate_index_name in aggregate_indexes: aggregate_index = Index(aggregate_index_name) body = { "properties": {"published_policy.fo": { "type": "text", "fields": { "keyword": { "type": "keyword", "ignore_above": 256 } } } } } doc = "doc" fo_field = "published_policy.fo" fo = "fo" fo_mapping = aggregate_index.get_field_mapping(fields=[fo_field])[ aggregate_index_name]["mappings"][doc][fo_field]["mapping"][fo] fo_type = fo_mapping["type"] if fo_type == "long": aggregate_index.put_mapping(doc_type=doc, body=body) for forensic_index in forensic_indexes: pass ``` > elasticsearch.exceptions.RequestError: RequestError(400, 'illegal\_argument\_exception', 'mapper [published\_policy.fo] of different type, current\_type [long], merged\_type [text]') What am I doing wrong, and how can I fix this mess? ---
**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\ **Post date:** [November 16, 2018, 3:38am UTC](https://discuss.elastic.co/t/how-can-i-change-an-existing-field-type-using-python/156968/2 "2018-11-16T03:38:58Z")
You cannot change a mapping once it is in place. Your best option would be to use a template and then update that, so future indices use the correct format. ---
**Author:** ![seanthegeek](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/seanthegeek/32/33421_2.png) [@seanthegeek](https://discuss.elastic.co/u/seanthegeek)\ **Post date:** [November 16, 2018, 3:44am UTC](https://discuss.elastic.co/t/how-can-i-change-an-existing-field-type-using-python/156968/3 "2018-11-16T03:44:29Z")
Thanks for the very fast reply. Is there any way to copy the existing data over to a new index with the correct mapping, so I don't lose data? ---
**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\ **Post date:** [November 16, 2018, 4:03am UTC](https://discuss.elastic.co/t/how-can-i-change-an-existing-field-type-using-python/156968/4 "2018-11-16T04:03:59Z")
You can do a reindex into a new index, then delete the old index and put an alias on the new index so it can still be queried via the original name. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [December 14, 2018, 4:04am UTC](https://discuss.elastic.co/t/how-can-i-change-an-existing-field-type-using-python/156968/5 "2018-12-14T04:04:06Z")
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