How to append on existing field with elasticsearch python? - python-3.x

Question

I am using kibana and Elasticsearch version 5.1.1 and python version 3.6.
I have created my index like this
put_books
The function to add a user is this one :
def add_user(first_name, last_name, age, mail):
doc = {"first_name": "" + first_name, "last_name": "" + last_name, "age": age, "email": "" + mail}
global id_user
res = es.index(index="books", doc_type="user", id=id_user, body=doc)
id_user += 1
print(res['result'])
and to add preferences :
def add_preferences(preferences, i):
doc = es.get(index="books", doc_type="user", id=id_book)
res = es.update(index="books", doc_type="user", id=i, body={'doc':{"keyword_preferences": preferences}})
My problem is here : when I want to add preferences, it success but if I want to add again preferences, it replace it :
id_user = 1
nom = "nom_1"
prenom = "prenom_1"
age = 45
email = "adresse_mail_1"
add_user(prenom, nom, age, email)
add_preferences("comique", 1)
add_preferences("horreur", 1)
get_user(1)
the result is :
updated
{'first_name': 'prenom_1', 'last_name': 'nom_1', 'age': 45, 'email': 'adresse_mail_1', 'keyword_preferences': 'horreur'}
Finally, the solution was :
POST /books/user/1/_update
{
"script" : {
"inline": "ctx._source.keyword_preferences += params.preference",
"lang": "painless",
"params" : {
"preference" : ["comique"]
}
}
}

Answer 1

The new function is :
def add_preferences(preferences, i):
doc = es.get(index="books", doc_type="user", id=i)
res = es.update(index="books", doc_type="user", id=i, body={'doc': {'keyword_preferences': [{"preferences": preferences}]}})
The mapping is done and now I've got the result :
{'first_name': 'prenom_1', 'last_name': 'nom_1', 'age': 45, 'email': 'mail_1', 'keyword_preferences': [{'preferences': 'horreur'}]}
So, it has replaced the first preference "comique" by "horreur"

Answer 2

Edited. example answer for your question.
Index a doc
POST /books/user/1
{
"keyword_preferences": ["comique"]
}
Now, update a doc to append horreur in keyword_preferences key.
POST /books/user/1/_update
{
"script": "ctx._source.keyword_preferences += keyword_preferences",
"params": {
"keyword_preferences": ["horreur"]
},
"lang": "groovy"
}
This will update keyword_preferences as ["comique", "horreur"].
If update API throws as exception {"type":"script_exception","reason":"scripts of type [inline], operation [update] and lang [groovy] are disabled"}, then you need to config elasticsearch.yml. Add script.engine.groovy.inline.update: on script.groovy.sandbox.enabled: true in elasticsearch.yml and restart you elasticsearch. I hope this helps.