# Problem with \_id path setting and fields with periods
**URL:** https://discuss.elastic.co/t/problem-with--id-path-setting-and-fields-with-periods/10451
**Category:** Elasticsearch
**Created:** [January 22, 2013, 2:34pm UTC](https://discuss.elastic.co/t/problem-with--id-path-setting-and-fields-with-periods/10451 "2013-01-22T14:34:09Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@hanafy\_ash](https://discuss.elastic.co/u/hanafy_ash)
#### Post date: [January 22, 2013, 2:34pm UTC](https://discuss.elastic.co/t/problem-with--id-path-setting-and-fields-with-periods/10451/1 "2013-01-22T14:34:09Z")
Hello everyone! Searched the group for an answer to this question but
couldn't find anything. My apologies if something similar was posted.
We've created a mapping according to this documentation to try to tell
ElasticSearch where to pull the '\_id' field from:
[http://www.elasticsearch.org/guide/reference/mapping/id-field.html](http://www.elasticsearch.org/guide/reference/mapping/id-field.html)
The mapping looks like:
{
"document" : {
"\_id" : {
"path" : "A.field"
}
}
}
This does not seem to work, because ES is treating the period as JSON
dot-notation. We've tried to escape the period to no avail. So the
documents we post look like:
{"A.field": "4000/1"}
But ES expects it to look like:
{"A": {"field": "4000/1"}}
So we end up having an auto-generated "\_id" anyways.
A couple of questions:
- Are there other "gotchas" like this caused by having periods in fields?
Is that just generally a bad idea?
- Is it recommended to not overwrite the "\_id" field? Our IDs for our
documents look like that above; are string IDs a bad idea? Is the slash a
problem? Does it affect hashing/distribution of documents?
Thanks in advance for the help!
- Ash
--
---
### Author:  [@Clinton\_Gormley](https://discuss.elastic.co/u/Clinton_Gormley)
#### Post date: [January 22, 2013, 2:48pm UTC](https://discuss.elastic.co/t/problem-with--id-path-setting-and-fields-with-periods/10451/2 "2013-01-22T14:48:27Z")
Hiya Ash
> This does not seem to work, because ES is treating the period as JSON
> dot-notation. We've tried to escape the period to no avail. So the
> documents we post look like:
>
> {"A.field": "4000/1"}
>
> But ES expects it to look like:
>
> {"A": {"field": "4000/1"}}
>
> So we end up having an auto-generated "\_id" anyways.
>
> A couple of questions:
>
> - Are there other "gotchas" like this caused by having periods in
> fields? Is that just generally a bad idea?
It is generally a bad idea.
> - Is it recommended to not overwrite the "\_id" field? Our IDs for our
> documents look like that above; are string IDs a bad idea? Is the
> slash a problem? Does it affect hashing/distribution of documents?
It is fine to override the \_id field. The slash may be tricky, because
it needs to be passed in the URL, so you should make sure that it is
always URI escaped: 4000%2F1
clint
--
---
### Author:  [@hanafy\_ash](https://discuss.elastic.co/u/hanafy_ash)
#### Post date: [January 23, 2013, 1:29pm UTC](https://discuss.elastic.co/t/problem-with--id-path-setting-and-fields-with-periods/10451/3 "2013-01-23T13:29:42Z")
Thanks for the quick reply Clinton!
I figured it would be a bad idea to have periods in fields (due to Object
type and JSON dot notation for referencing nested fields), but the system
we are migrating from has a period in just about every field. I am assuming
there is no such thing as "field aliasing" in ES? Could not confirm or
deny this based on the brief research I did.
And thanks for the heads up with the slashes in the \_id field. Figured it
had to be URI escaped.
- Ash
On Tuesday, January 22, 2013 9:48:27 AM UTC-5, Clinton Gormley wrote:
> Hiya Ash
>
> > This does not seem to work, because ES is treating the period as JSON
> > dot-notation. We've tried to escape the period to no avail. So the
> > documents we post look like:
> >
> > {"A.field": "4000/1"}
> >
> > But ES expects it to look like:
> >
> > {"A": {"field": "4000/1"}}
> >
> > So we end up having an auto-generated "\_id" anyways.
> >
> > A couple of questions:
> >
> > - Are there other "gotchas" like this caused by having periods in
> > fields? Is that just generally a bad idea?
>
> It is generally a bad idea.
>
> > - Is it recommended to not overwrite the "\_id" field? Our IDs for our
> > documents look like that above; are string IDs a bad idea? Is the
> > slash a problem? Does it affect hashing/distribution of documents?
>
> It is fine to override the \_id field. The slash may be tricky, because
> it needs to be passed in the URL, so you should make sure that it is
> always URI escaped: 4000%2F1
>
> clint
--
---
### Author:  [@Clinton\_Gormley](https://discuss.elastic.co/u/Clinton_Gormley)
#### Post date: [January 23, 2013, 1:50pm UTC](https://discuss.elastic.co/t/problem-with--id-path-setting-and-fields-with-periods/10451/4 "2013-01-23T13:50:49Z")
Hiya Ash
> I figured it would be a bad idea to have periods in fields (due to
> Object type and JSON dot notation for referencing nested fields), but
> the system we are migrating from has a period in just about every
> field. I am assuming there is no such thing as "field aliasing" in ES?
> Could not confirm or deny this based on the brief research I did.
You could try using the 'index\_name' parameter in the field mapping to
control in field names in the index, but that introduces a level of
complexity that would be best avoided.
You say that you're migrating from an old system - it'd surely be better
in the long run to go ahead and rename your fields
clint
--
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 6, 2017, 2:55am UTC](https://discuss.elastic.co/t/problem-with--id-path-setting-and-fields-with-periods/10451/5 "2017-07-06T02:55:01Z")