# Conditional for empty string in field

**URL:** <https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182>\
**Category:** Logstash\
**Created:** [March 2, 2017, 4:51pm UTC](https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182 "2017-03-02T16:51:20Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![ENG618](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/eng618/32/59206_2.png) [@ENG618](https://discuss.elastic.co/u/ENG618)\
**Post date:** [March 2, 2017, 4:51pm UTC](https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182/1 "2017-03-02T16:51:20Z")

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I'm trying to drop logs from the config that contain a field with blank string for a particular field. e.g.

```auto
if [foo] == "" { drop{} }

```

This is not working as when the logs come through it shows as `"foo" => "\"\""`

A little background, I'm using the `kv { }` filter prior to this conditional. Also using `stdout { codec => rubydebug }`.

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<div class="post-metadata">

**Author:** ![rcowart](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rcowart/32/88091_2.png) [@rcowart](https://discuss.elastic.co/u/rcowart)\
**Post date:** [March 2, 2017, 5:24pm UTC](https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182/2 "2017-03-02T17:24:02Z")

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I always use the following to check for an empty string.

```
if [foo] !~ /.+/ { drop { } }
```

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<div class="post-metadata">

**Author:** ![ENG618](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/eng618/32/59206_2.png) [@ENG618](https://discuss.elastic.co/u/ENG618)\
**Post date:** [March 2, 2017, 5:45pm UTC](https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182/3 "2017-03-02T17:45:13Z")

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This is seeming to drop everything. Even if there is content in `foo`. Some logs come with `foo=""` and some come with `foo="bar"`. When I put this conditional in the config, I don't receive any logs.

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**Author:** ![glmrenard](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/glmrenard/32/15393_2.png) [@glmrenard](https://discuss.elastic.co/u/glmrenard)\
**Post date:** [March 2, 2017, 9:27pm UTC](https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182/4 "2017-03-02T21:27:08Z")

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Hello,

I would try something like  
`if [foo] and [foo]=="" {drop { } }`

regards,

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**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\
**Post date:** [March 7, 2017, 6:26am UTC](https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182/5 "2017-03-07T06:26:34Z")

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With `"foo" => "\"\""` the string isn't empty; it contains two double quotes. Perhaps you should use the mutate filter's gsub option to remove leading and trailing double quotes before your conditional?

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**Author:** ![ENG618](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/eng618/32/59206_2.png) [@ENG618](https://discuss.elastic.co/u/ENG618)\
**Post date:** [March 7, 2017, 4:08pm UTC](https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182/6 "2017-03-07T16:08:04Z")

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This did not seem to work either, same behavior as previously described...this drops all messages.

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<div class="post-metadata">

**Author:** ![ENG618](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/eng618/32/59206_2.png) [@ENG618](https://discuss.elastic.co/u/ENG618)\
**Post date:** [March 21, 2017, 4:03pm UTC](https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182/7 "2017-03-21T16:03:08Z")

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So I ended up having to modify the data that was coming in, and got it working. I think the above solutions would have worked in a different scenario.

Thanks everyone for your help

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<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:** [April 18, 2017, 4:03pm UTC](https://discuss.elastic.co/t/conditional-for-empty-string-in-field/77182/8 "2017-04-18T16:03:09Z")

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