Elasticsearch DSL
Elasticsearch DSL is a high-level library whose aim is to help with writing and running queries against Elasticsearch. It is built on top of the official low-level client (elasticsearch-py).
It provides a more convenient and idiomatic way to write and manipulate queries. It stays close to the Elasticsearch JSON DSL, mirroring its terminology and structure. It exposes the whole range of the DSL from Python either directly using defined classes or a queryset-like expressions.
It also provides an optional wrapper for working with documents as Python objects: defining mappings, retrieving and saving documents, wrapping the document data in user-defined classes.
To use the other Elasticsearch APIs (eg. cluster health) just use the underlying client.
Installation
pip install elasticsearch-dsl
Examples
Please see the examples directory to see some complex examples using elasticsearch-dsl.
Compatibility
The library is compatible with all Elasticsearch versions since 2.x but you have to use a matching major version:
For Elasticsearch 7.0 and later, use the major version 7 (7.x.y) of the library.
For Elasticsearch 6.0 and later, use the major version 6 (6.x.y) of the library.
For Elasticsearch 5.0 and later, use the major version 5 (5.x.y) of the library.
For Elasticsearch 2.0 and later, use the major version 2 (2.x.y) of the library.
The recommended way to set your requirements in your setup.py or requirements.txt is:
# Elasticsearch 7.x elasticsearch-dsl>=7.0.0,<8.0.0 # Elasticsearch 6.x elasticsearch-dsl>=6.0.0,<7.0.0 # Elasticsearch 5.x elasticsearch-dsl>=5.0.0,<6.0.0 # Elasticsearch 2.x elasticsearch-dsl>=2.0.0,<3.0.0
The development is happening on master, older branches only get bugfix releases
Search Example
Let's have a typical search request written directly as a dict:
from elasticsearch import Elasticsearch
client = Elasticsearch()
response = client.search(
index="my-index",
body={
"query": {
"bool": {
"must": [{"match": {"title": "python"}}],
"must_not": [{"match": {"description": "beta"}}],
"filter": [{"term": {"category": "search"}}]
}
},
"aggs" : {
"per_tag": {
"terms": {"field": "tags"},
"aggs": {
"max_lines": {"max": {"field": "lines"}}
}
}
}
}
)
for hit in response['hits']['hits']:
print(hit['_score'], hit['_source']['title'])
for tag in response['aggregations']['per_tag']['buckets']:
print(tag['key'], tag['max_lines']['value'])
The problem with this approach is that it is very verbose, prone to syntax mistakes like incorrect nesting, hard to modify (eg. adding another filter) and definitely not fun to write.
Let's rewrite the example using the Python DSL:
from elasticsearch import Elasticsearch
from elasticsearch_dsl import Search
client = Elasticsearch()
s = Search(using=client, index="my-index") \
.filter("term", category="search") \
.query("match", title="python") \
.exclude("match", description="beta")
s.aggs.bucket('per_tag', 'terms', field='tags') \
.metric('max_lines', 'max', field='lines')
response = s.execute()
for hit in response:
print(hit.meta.score, hit.title)
for tag in response.aggregations.per_tag.buckets:
print(tag.key, tag.max_lines.value)
As you see, the library took care of:
- creating appropriate
Queryobjects by name (eq. "match")- composing queries into a compound
boolquery- putting the
termquery in a filter context of theboolquery- providing a convenient access to response data
- no curly or square brackets everywhere
Persistence Example
Let's have a simple Python class representing an article in a blogging system:
from datetime import datetime
from elasticsearch_dsl import Document, Date, Integer, Keyword, Text, connections
# Define a default Elasticsearch client
connections.create_connection(hosts=['localhost'])
class Article(Document):
title = Text(analyzer='snowball', fields={'raw': Keyword()})
body = Text(analyzer='snowball')
tags = Keyword()
published_from = Date()
lines = Integer()
class Index:
name = 'blog'
settings = {
"number_of_shards": 2,
}
def save(self, ** kwargs):
self.lines = len(self.body.split())
return super(Article, self).save(** kwargs)
def is_published(self):
return datetime.now() > self.published_from
# create the mappings in elasticsearch
Article.init()
# create and save and article
article = Article(meta={'id': 42}, title='Hello world!', tags=['test'])
article.body = ''' looong text '''
article.published_from = datetime.now()
article.save()
article = Article.get(id=42)
print(article.is_published())
# Display cluster health
print(connections.get_connection().cluster.health())
In this example you can see:
- providing a default connection
- defining fields with mapping configuration
- setting index name
- defining custom methods
- overriding the built-in
.save()method to hook into the persistence life cycle- retrieving and saving the object into Elasticsearch
- accessing the underlying client for other APIs
You can see more in the persistence chapter of the documentation.
Migration from elasticsearch-py
You don't have to port your entire application to get the benefits of the Python DSL, you can start gradually by creating a Search object from your existing dict, modifying it using the API and serializing it back to a dict:
body = {...} # insert complicated query here
# Convert to Search object
s = Search.from_dict(body)
# Add some filters, aggregations, queries, ...
s.filter("term", tags="python")
# Convert back to dict to plug back into existing code
body = s.to_dict()
Development
Activate Virtual Environment (virtualenvs):
$ virtualenv venv
$ source venv/bin/activate
To install all of the dependencies necessary for development, run:
$ pip install -e '.[develop]'
To run all of the tests for elasticsearch-dsl-py, run:
$ python setup.py test
Alternatively, it is possible to use the run_tests.py script in test_elasticsearch_dsl, which wraps pytest, to run subsets of the test suite. Some examples can be seen below:
# Run all of the tests in `test_elasticsearch_dsl/test_analysis.py`
$ ./run_tests.py test_analysis.py
# Run only the `test_analyzer_serializes_as_name` test.
$ ./run_tests.py test_analysis.py::test_analyzer_serializes_as_name
pytest will skip tests from test_elasticsearch_dsl/test_integration unless there is an instance of Elasticsearch on which a connection can occur. By default, the test connection is attempted at localhost:9200, based on the defaults specified in the elasticsearch-py Connection class. Because running the integration tests will cause destructive changes to the Elasticsearch cluster, only run them when the associated cluster is empty. As such, if the Elasticsearch instance at localhost:9200 does not meet these requirements, it is possible to specify a different test Elasticsearch server through the TEST_ES_SERVER environment variable.
$ TEST_ES_SERVER=my-test-server:9201 ./run_tests
Documentation
Documentation is available at https://elasticsearch-dsl.readthedocs.io.
Contribution Guide
Want to hack on Elasticsearch DSL? Awesome! We have Contribution-Guide.
License
Copyright 2013 Elasticsearch
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
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