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	Continuation of #5147 .. typification of the engine processors. BTW: - removed obsolete engine property https_support - fixed & improved currency_convert - engine instances can now implement a engine.setup method [#5147] https://github.com/searxng/searxng/pull/5147 Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
		
			
				
	
	
		
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			252 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			ReStructuredText
		
	
	
	
	
	
| .. _engines-dev:
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| 
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| ===============
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| Engine Overview
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| ===============
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| 
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| .. contents::
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|    :depth: 3
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|    :local:
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|    :backlinks: entry
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| 
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| .. _metasearch-engine: https://en.wikipedia.org/wiki/Metasearch_engine
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| 
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| .. sidebar:: Further reading ..
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| 
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|    - :ref:`configured engines`
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|    - :ref:`settings engines`
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| 
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| SearXNG is a metasearch-engine_, so it uses different search engines to provide
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| better results.
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| 
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| Because there is no general search API which could be used for every search
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| engine, an adapter has to be built between SearXNG and the external search
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| engines.  Adapters are stored under the folder :origin:`searx/engines`.
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| 
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| .. _general engine configuration:
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| 
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| General Engine Configuration
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| ============================
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| 
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| It is required to tell SearXNG the type of results the engine provides. The
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| arguments can be set in the engine file or in the settings file (normally
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| ``settings.yml``). The arguments in the settings file override the ones in the
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| engine file.
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| 
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| It does not matter if an option is stored in the engine file or in the settings.
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| However, the standard way is the following:
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| 
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| .. _engine file:
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| 
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| Engine File
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| -----------
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| 
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| .. table:: Common options in the engine module
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|    :width: 100%
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| 
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|    ======================= =========== ========================================================
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|    argument                type        information
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|    ======================= =========== ========================================================
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|    categories              list        categories, in which the engine is working
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|    paging                  boolean     support multiple pages
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|    time_range_support      boolean     support search time range
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|    engine_type             str         - ``online`` :ref:`[ref] <online engines>` by
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|                                          default, other possibles values are:
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|                                        - ``offline`` :ref:`[ref] <offline engines>`
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|                                        - ``online_dictionary`` :ref:`[ref] <online dictionary>`
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|                                        - ``online_currency`` :ref:`[ref] <online currency>`
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|                                        - ``online_url_search`` :ref:`[ref] <online url search>`
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|    ======================= =========== ========================================================
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| 
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| .. _engine settings:
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| 
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| Engine ``settings.yml``
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| -----------------------
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| 
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| For a more  detailed description, see :ref:`settings engines` in the :ref:`settings.yml`.
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| 
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| .. table:: Common options in the engine setup (``settings.yml``)
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|    :width: 100%
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| 
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|    ======================= =========== ==================================================
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|    argument                type        information
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|    ======================= =========== ==================================================
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|    name                    string      name of search-engine
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|    engine                  string      name of searxng-engine (file name without ``.py``)
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|    enable_http             bool        enable HTTP (by default only HTTPS is enabled).
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|    shortcut                string      shortcut of search-engine
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|    timeout                 string      specific timeout for search-engine
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|    display_error_messages  boolean     display error messages on the web UI
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|    proxies                 dict        set proxies for a specific engine
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|                                        (e.g. ``proxies : {http: socks5://proxy:port,
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|                                        https: socks5://proxy:port}``)
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|    ======================= =========== ==================================================
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| 
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| .. _engine overrides:
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| 
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| Overrides
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| ---------
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| 
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| A few of the options have default values in the namespace of the engine's python
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| module, but are often overwritten by the settings.  If ``None`` is assigned to an
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| option in the engine file, it has to be redefined in the settings, otherwise
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| SearXNG will not start with that engine (global names with a leading underline can
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| be ``None``).
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| 
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| Here is an very simple example of the global names in the namespace of engine's
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| module:
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| 
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| .. code:: python
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| 
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|    # engine dependent config
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|    categories = ['general']
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|    paging = True
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|    _non_overwritten_global = 'foo'
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| 
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| 
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| .. table:: The naming of overrides is arbitrary / recommended overrides are:
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|    :width: 100%
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| 
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|    ======================= =========== ===========================================
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|    argument                type        information
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|    ======================= =========== ===========================================
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|    base_url                string      base-url, can be overwritten to use same
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|                                        engine on other URL
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|    number_of_results       int         maximum number of results per request
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|    language                string      ISO code of language and country like en_US
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|    api_key                 string      api-key if required by engine
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|    ======================= =========== ===========================================
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| 
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| .. _engine request:
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| 
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| Making a Request
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| ================
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| 
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| To perform a search an URL have to be specified.  In addition to specifying an
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| URL, arguments can be passed to the query.
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| 
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| .. _engine request arguments:
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| 
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| Passed Arguments (request)
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| --------------------------
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| 
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| These arguments can be used to construct the search query.  Furthermore,
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| parameters with default value can be redefined for special purposes.
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| 
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| .. _engine request online:
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| 
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| .. table:: If the ``engine_type`` is :py:obj:`online
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|            <searx.search.processors.online.OnlineProcessor.get_params>`
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|    :width: 100%
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| 
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|    ====================== ============== ========================================================================
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|    argument               type           default-value, information
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|    ====================== ============== ========================================================================
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|    url                    str            ``''``
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|    method                 str            ``'GET'``
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|    headers                dict           ``{}``
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|    data                   dict           ``{}``
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|    cookies                dict           ``{}``
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|    verify                 bool           ``True``
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|    headers.User-Agent     str            a random User-Agent
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|    category               str            current category, like ``'general'``
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|    safesearch             int            ``0``, between ``0`` and ``2`` (normal, moderate, strict)
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|    time_range             Optional[str]  ``None``, can be ``day``, ``week``, ``month``, ``year``
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|    pageno                 int            current pagenumber
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|    searxng_locale         str            SearXNG's locale selected by user.  Specific language code like
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|                                          ``'en'``, ``'en-US'``, or ``'all'`` if unspecified.
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|    ====================== ============== ========================================================================
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| 
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| 
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| .. _engine request online_dictionary:
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| 
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| .. table:: If the ``engine_type`` is :py:obj:`online_dictionary
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|            <searx.search.processors.online_dictionary.OnlineDictionaryProcessor.get_params>`,
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|            in addition to the :ref:`online <engine request online>` arguments:
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|    :width: 100%
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| 
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|    ====================== ============== ========================================================================
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|    argument               type           default-value, information
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|    ====================== ============== ========================================================================
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|    from_lang              str            specific language code like ``'en_US'``
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|    to_lang                str            specific language code like ``'en_US'``
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|    query                  str            the text query without the languages
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|    ====================== ============== ========================================================================
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| 
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| .. _engine request online_currency:
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| 
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| .. table:: If the ``engine_type`` is :py:obj:`online_currency
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|            <searx.search.processors.online_currency.OnlineCurrencyProcessor.get_params>`,
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|            in addition to the :ref:`online <engine request online>` arguments:
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|    :width: 100%
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| 
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|    ====================== ============== ========================================================================
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|    argument               type           default-value, information
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|    ====================== ============== ========================================================================
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|    amount                 float          the amount to convert
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|    from                   str            ISO 4217 code
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|    to                     str            ISO 4217 code
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|    from_name              str            currency name
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|    to_name                str            currency name
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|    ====================== ============== ========================================================================
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| 
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| .. _engine request online_url_search:
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| 
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| .. table:: If the ``engine_type`` is :py:obj:`online_url_search
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|            <searx.search.processors.online_url_search.OnlineUrlSearchProcessor.get_params>`,
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|            in addition to the :ref:`online <engine request online>` arguments:
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|    :width: 100%
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| 
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|    ====================== ============== ========================================================================
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|    argument               type           default-value, information
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|    ====================== ============== ========================================================================
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|    search_url             dict           URLs from the search query:
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| 
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|                                          .. code:: python
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| 
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|                                             {
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|                                               'http': str,
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|                                               'ftp': str,
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|                                               'data:image': str
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|                                             }
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|    ====================== ============== ========================================================================
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| 
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| Specify Request
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| ---------------
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| 
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| The function :py:func:`def request(query, params):
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| <searx.engines.demo_online.request>` always returns the ``params`` variable, the
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| following parameters can be used to specify a search request:
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| 
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| .. table::
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|    :width: 100%
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| 
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|    =================== =========== ==========================================================================
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|    argument            type        information
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|    =================== =========== ==========================================================================
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|    url                 str         requested url
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|    method              str         HTTP request method
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|    headers             dict        HTTP header information
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|    data                dict        HTTP data information
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|    cookies             dict        HTTP cookies
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|    verify              bool        Performing SSL-Validity check
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|    allow_redirects     bool        Follow redirects
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|    max_redirects       int         maximum redirects, hard limit
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|    soft_max_redirects  int         maximum redirects, soft limit. Record an error but don't stop the engine
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|    raise_for_httperror bool        True by default: raise an exception if the HTTP code of response is >= 300
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|    =================== =========== ==========================================================================
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| 
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| 
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| Making a Response
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| =================
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| 
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| In the ``response`` function of the engine, the HTTP response (``resp``) is
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| parsed and a list of results is returned.
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| 
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| A engine can append result-items of different media-types and different
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| result-types to the result list.  The list of the result items is render to HTML
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| by templates.  For more details read section:
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| 
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| - :ref:`simple theme templates`
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| - :ref:`result types`
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