.. _engines-dev:
===============
Engine Overview
===============
.. contents::
:depth: 3
:local:
:backlinks: entry
.. _metasearch-engine: https://en.wikipedia.org/wiki/Metasearch_engine
.. sidebar:: Further reading ..
- :ref:`configured engines`
- :ref:`settings engines`
SearXNG is a metasearch-engine_, so it uses different search engines to provide
better results.
Because there is no general search API which could be used for every search
engine, an adapter has to be built between SearXNG and the external search
engines. Adapters are stored under the folder :origin:`searx/engines`.
.. _general engine configuration:
General Engine Configuration
============================
It is required to tell SearXNG the type of results the engine provides. The
arguments can be set in the engine file or in the settings file (normally
``settings.yml``). The arguments in the settings file override the ones in the
engine file.
It does not matter if an option is stored in the engine file or in the settings.
However, the standard way is the following:
.. _engine file:
Engine File
-----------
.. table:: Common options in the engine module
:width: 100%
======================= =========== ========================================================
argument type information
======================= =========== ========================================================
categories list categories, in which the engine is working
paging boolean support multiple pages
time_range_support boolean support search time range
engine_type str - ``online`` :ref:`[ref] <online engines>` by
default, other possibles values are:
- ``offline`` :ref:`[ref] <offline engines>`
- ``online_dictionary`` :ref:`[ref] <online dictionary>`
- ``online_currency`` :ref:`[ref] <online currency>`
- ``online_url_search`` :ref:`[ref] <online url search>`
======================= =========== ========================================================
.. _engine settings:
Engine ``settings.yml``
-----------------------
For a more detailed description, see :ref:`settings engines` in the :ref:`settings.yml`.
.. table:: Common options in the engine setup (``settings.yml``)
:width: 100%
======================= =========== ==================================================
argument type information
======================= =========== ==================================================
name string name of search-engine
engine string name of searxng-engine (file name without ``.py``)
enable_http bool enable HTTP (by default only HTTPS is enabled).
shortcut string shortcut of search-engine
timeout string specific timeout for search-engine
display_error_messages boolean display error messages on the web UI
proxies dict set proxies for a specific engine
(e.g. ``proxies : {http: socks5://proxy:port,
https: socks5://proxy:port}``)
======================= =========== ==================================================
.. _engine overrides:
Overrides
---------
A few of the options have default values in the namespace of the engine's python
module, but are often overwritten by the settings. If ``None`` is assigned to an
option in the engine file, it has to be redefined in the settings, otherwise
SearXNG will not start with that engine (global names with a leading underline can
be ``None``).
Here is an very simple example of the global names in the namespace of engine's
module:
.. code:: python
# engine dependent config
categories = ['general']
paging = True
_non_overwritten_global = 'foo'
.. table:: The naming of overrides is arbitrary / recommended overrides are:
:width: 100%
======================= =========== ===========================================
argument type information
======================= =========== ===========================================
base_url string base-url, can be overwritten to use same
engine on other URL
number_of_results int maximum number of results per request
language string ISO code of language and country like en_US
api_key string api-key if required by engine
======================= =========== ===========================================
.. _engine request:
Making a Request
================
To perform a search an URL have to be specified. In addition to specifying an
URL, arguments can be passed to the query.
.. _engine request arguments:
Passed Arguments (request)
--------------------------
These arguments can be used to construct the search query. Furthermore,
parameters with default value can be redefined for special purposes.
.. _engine request online:
.. table:: If the ``engine_type`` is :py:obj:`online
<searx.search.processors.online.OnlineProcessor.get_params>`
:width: 100%
====================== ============== ========================================================================
argument type default-value, information
====================== ============== ========================================================================
url str ``''``
method str ``'GET'``
headers set ``{}``
data set ``{}``
cookies set ``{}``
verify bool ``True``
headers.User-Agent str a random User-Agent
category str current category, like ``'general'``
safesearch int ``0``, between ``0`` and ``2`` (normal, moderate, strict)
time_range Optional[str] ``None``, can be ``day``, ``week``, ``month``, ``year``
pageno int current pagenumber
searxng_locale str SearXNG's locale selected by user. Specific language code like
``'en'``, ``'en-US'``, or ``'all'`` if unspecified.
====================== ============== ========================================================================
.. _engine request online_dictionary:
.. table:: If the ``engine_type`` is :py:obj:`online_dictionary
<searx.search.processors.online_dictionary.OnlineDictionaryProcessor.get_params>`,
in addition to the :ref:`online <engine request online>` arguments:
:width: 100%
====================== ============== ========================================================================
argument type default-value, information
====================== ============== ========================================================================
from_lang str specific language code like ``'en_US'``
to_lang str specific language code like ``'en_US'``
query str the text query without the languages
====================== ============== ========================================================================
.. _engine request online_currency:
.. table:: If the ``engine_type`` is :py:obj:`online_currency
<searx.search.processors.online_currency.OnlineCurrencyProcessor.get_params>`,
in addition to the :ref:`online <engine request online>` arguments:
:width: 100%
====================== ============== ========================================================================
argument type default-value, information
====================== ============== ========================================================================
amount float the amount to convert
from str ISO 4217 code
to str ISO 4217 code
from_name str currency name
to_name str currency name
====================== ============== ========================================================================
.. _engine request online_url_search:
.. table:: If the ``engine_type`` is :py:obj:`online_url_search
<searx.search.processors.online_url_search.OnlineUrlSearchProcessor.get_params>`,
in addition to the :ref:`online <engine request online>` arguments:
:width: 100%
====================== ============== ========================================================================
argument type default-value, information
====================== ============== ========================================================================
search_url dict URLs from the search query:
.. code:: python
{
'http': str,
'ftp': str,
'data:image': str
}
====================== ============== ========================================================================
Specify Request
---------------
The function :py:func:`def request(query, params):
<searx.engines.demo_online.request>` always returns the ``params`` variable, the
following parameters can be used to specify a search request:
.. table::
:width: 100%
=================== =========== ==========================================================================
argument type information
=================== =========== ==========================================================================
url str requested url
method str HTTP request method
headers set HTTP header information
data set HTTP data information
cookies set HTTP cookies
verify bool Performing SSL-Validity check
allow_redirects bool Follow redirects
max_redirects int maximum redirects, hard limit
soft_max_redirects int maximum redirects, soft limit. Record an error but don't stop the engine
raise_for_httperror bool True by default: raise an exception if the HTTP code of response is >= 300
=================== =========== ==========================================================================
Making a Response
=================
In the ``response`` function of the engine, the HTTP response (``resp``) is
parsed and a list of results is returned.
A engine can append result-items of different media-types and different
result-types to the result list. The list of the result items is render to HTML
by templates. For more details read section:
- :ref:`simple theme templates`
- :ref:`result types`