Case Insensitive ElasticSearch Regular expressions

caseInsensitive.sense

# Delete any old test index

DELETE example_copy

# Create index with appropriate mappings/settings
# Note that the pattern is meant to not match anything so that the entire field is taken as the "token"
PUT example_copy
{
    "settings": {
        "analysis": {
            "analyzer": {
                "caseInsensitive": {
                    "type" : "pattern",
                    "pattern" : "abcdefghijklmnopqrstuvwxyzywx",
                    "filter" : ["lowercase"]
                }
            }
        }
    }, 
    "mappings": {
        "example" : {
            "properties": {
                "original" : {
                    "type": "string",
                    "copy_to": ["copied", "unindex"]
                },
                "copied" : {
                    "type": "string",
                    "index": "analyzed",
                    "analyzer": "caseInsensitive"
                },
                "unindex" : {
                    "type": "string",
                    "index": "not_analyzed"
                }
            }
        }
    }
}

# Create document
POST /example_copy/example
{
    "original" : "Hello There FRiend"
}

# Will return document
POST /example_copy/_search 
{
    "query": {
        "regexp" : {
            "original" : {
                "value" : "t.*"
            }
        }
    }
}

# Will return document
POST /example_copy/_search 
{
    "query": {
        "regexp" : {
            "copied" : {
                "value" : "h.*"
            }
        }
    }
}

# Will return document because case sensitive unindex field.
POST /example_copy/_search 
{
    "query": {
        "regexp" : {
            "unindex" : {
                "value" : "H.*"
            }
        }
    }
}

# Will NOT return document because the value in the field is 'h' not 'H' due to the lowercase filter
POST /example_copy/_search 
{
    "query": {
        "regexp" : {
            "copied" : {
                "value" : "H.*"
            }
        }
    }
}