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	Closes: https://github.com/searxng/searxng/issues/4370 Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
		
			
				
	
	
		
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			255 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			ReStructuredText
		
	
	
	
	
	
.. _engines-dev:
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===============
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Engine Overview
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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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.. _metasearch-engine: https://en.wikipedia.org/wiki/Metasearch_engine
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.. sidebar:: Further reading ..
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   - :ref:`configured engines`
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   - :ref:`settings engines`
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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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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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.. _general engine configuration:
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General Engine Configuration
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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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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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.. _engine file:
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Engine File
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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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   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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.. _engine settings:
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Engine ``settings.yml``
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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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.. table:: Common options in the engine setup (``settings.yml``)
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   :width: 100%
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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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.. _engine overrides:
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Overrides
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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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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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.. code:: python
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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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.. table:: The naming of overrides is arbitrary / recommended overrides are:
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   :width: 100%
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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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.. _engine request:
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Making a Request
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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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.. _engine request arguments:
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Passed Arguments (request)
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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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.. _engine request online:
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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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   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                set            ``{}``
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   data                   set            ``{}``
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   cookies                set            ``{}``
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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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.. _engine request online_dictionary:
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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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   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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.. _engine request online_currency:
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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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   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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.. _engine request online_url_search:
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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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   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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                                         .. code:: python
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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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Specify Request
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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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.. table::
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   :width: 100%
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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             set         HTTP header information
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   data                set         HTTP data information
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   cookies             set         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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Making a Response
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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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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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- :ref:`simple theme templates`
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- :ref:`result types`
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