# Lowercase processor - \[field\] property isn't a string, but of type \[java.util.ArrayList\]

**URL:** <https://discuss.elastic.co/t/lowercase-processor-field-property-isnt-a-string-but-of-type-java-util-arraylist/278340>\
**Category:** Elasticsearch\
**Tags:** ingest-pipeline\
**Created:** [July 10, 2021, 5:49pm UTC](https://discuss.elastic.co/t/lowercase-processor-field-property-isnt-a-string-but-of-type-java-util-arraylist/278340 "2021-07-10T17:49:11Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![f4d0](https://avatars.discourse-cdn.com/v4/letter/f/f14d63/32.png) [@f4d0](https://discuss.elastic.co/u/f4d0)\
**Post date:** [July 10, 2021, 5:49pm UTC](https://discuss.elastic.co/t/lowercase-processor-field-property-isnt-a-string-but-of-type-java-util-arraylist/278340/1 "2021-07-10T17:49:11Z")

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Hi,

Elasticsearch version: 7.13.3  
Python module in use: elasticsearch-7.13.3

Pipeline:

```auto
B_AutoReply_pipeline = """
{
    "processors":[
        {
            "date": {
                "field": "Parsed_Datetime",
                "formats": ["strict_date_optional_time","yyyy-MM-dd HH:mm:ss"],
                "ignore_failure": true
            }
        },
        {
            "lowercase": {
                "field": ["Flag_1","Flag_2","Flag_2"],
                "ignore_failure": true
            }
        }
    ]
}
"""

```

I am having issues with the **field** property under lowercase processor. As a consequence it is not creating the pipeline.

I get an error saying that the field is not a string.

![Processor_Property](https://us1.discourse-cdn.com/elastic/original/3X/b/9/b963ac78b2eb5f153eccae6a3bdf6e55e2db144d.png)

According to Elasticsearch documentation it is written about this processor: "Converts a string to its lowercase equivalent. **If the field is an array of strings** , all members of the array will be converted."

Does anyone know what am I doing wrong.

Thanks for your attention on this.

Regards,  
f4d0

---

<div class="post-metadata">

**Author:** ![spinscale](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/spinscale/32/25011_2.png) [@spinscale](https://discuss.elastic.co/u/spinscale)\
**Post date:** [July 12, 2021, 8:18am UTC](https://discuss.elastic.co/t/lowercase-processor-field-property-isnt-a-string-but-of-type-java-util-arraylist/278340/2 "2021-07-12T08:18:26Z")

</div>

You need to specify three lowercase processor, one for each field (`field1`, `field2`, `field3`). The docs mention

> If the field is an array of strings, all members of the array will be converted.

this however refers to the **value** of the field, so if your JSON looks like `field1: ["A", "B", "C"]`

hope that helps.

---

<div class="post-metadata">

**Author:** ![f4d0](https://avatars.discourse-cdn.com/v4/letter/f/f14d63/32.png) [@f4d0](https://discuss.elastic.co/u/f4d0)\
**Post date:** [July 12, 2021, 9:04am UTC](https://discuss.elastic.co/t/lowercase-processor-field-property-isnt-a-string-but-of-type-java-util-arraylist/278340/3 "2021-07-12T09:04:11Z")

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Yes, if does help a lot! I guess I miss interpreted it. I've changed the pipeline and now it works good.  
The challenge for me is that I have some pipelines that have +50 to fields to convert. Either way, it is solved.

Thanks so much @spinscale

---

<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 9, 2021, 9:04am UTC](https://discuss.elastic.co/t/lowercase-processor-field-property-isnt-a-string-but-of-type-java-util-arraylist/278340/4 "2021-08-09T09:04:39Z")

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