Elasticsearch in Django - sort alphabetically - django

Question

I have a following doc:
#brand.doc_type
class BrandDocument(DocType):
class Meta:
model = Brand
id = IntegerField()
name = StringField(
fields={
'raw': {
'type': 'keyword',
'fielddata': True,
}
},
)
lookup_name = StringField(
fields={
'raw': {
'type': 'string',
}
},
)
and I try to make a lookup using this:
BrandDocument.search().sort({
'name.keyword': order,
})
The problem is that I'm getting results sorted in a case sensitive way, which means that instead of 'a', 'A', 'ab', 'AB' I get 'A', 'AB', 'a', 'ab'. How can this be fixed?
EDIT After some additional search I've come up with something like this:
lowercase_normalizer = normalizer(
'lowercase_normalizer',
filter=['lowercase']
)
lowercase_analyzer = analyzer(
'lowercase_analyzer',
tokenizer="keyword",
filter=['lowercase'],
)
#brand.doc_type
class BrandDocument(DocType):
class Meta:
model = Brand
id = IntegerField()
name = StringField(
analyzer=lowercase_analyzer,
fields={
'raw': Keyword(normalizer=lowercase_normalizer, fielddata=True),
},
)
The issue persists, however, and I can't find in the docs how this normalizer should be used.

Answer 1

I would suggest to create a custom analyzer with lowercase filter and apply it to the field while indexing.
So you have to update the following in the index settings:
{
"index": {
"analysis": {
"analyzer": {
"custom_sort": {
"tokenizer": "keyword",
"filter": [
"lowercase"
]
}
}
}
}
}
Add a field (based on which you need to sort) in mapping with the custom_sort analyzer as below:
{
"properties":{
"sortField":{
"type":"text",
"analyzer":"custom_sort"
}
}
}
If the field already exists in mapping then you can add a sub fields to the existing field with the analyzer as below.
Assuming the field name having type as keyword already exists, update it as:
{
"properties":{
"name":{
"type": "keyword",
"fields":{
"sortval":{
"type":"text",
"analyzer":"custom_sort"
}
}
}
}
}
Once done you need to reindex your data so that lowercase values are indexed. Then you can use the field to sort as:
Case 1 (new field):
"sort": [
{
"sortField": "desc"
}
]
Case 2 (sub field):
"sort": [
{
"name.sortval": "desc"
}
]