59 lines
9.5 KiB
HTML
59 lines
9.5 KiB
HTML
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<!-- Generated by HsColour, http://code.haskell.org/~malcolm/hscolour/ -->
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<title>src/Servant/API/Get.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE TypeFamilies #-}</span>
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<a name="line-2"></a><span class='hs-comment'>{-# LANGUAGE OverloadedStrings #-}</span>
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<a name="line-3"></a><span class='hs-comment'>{-# LANGUAGE ScopedTypeVariables #-}</span>
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<a name="line-4"></a><span class='hs-comment'>{-# LANGUAGE DeriveDataTypeable #-}</span>
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<a name="line-5"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Servant</span><span class='hs-varop'>.</span><span class='hs-conid'>API</span><span class='hs-varop'>.</span><span class='hs-conid'>Get</span> <span class='hs-keyword'>where</span>
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<a name="line-6"></a>
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<a name="line-7"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Either</span>
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<a name="line-8"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Aeson</span>
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<a name="line-9"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Proxy</span>
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<a name="line-10"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>String</span><span class='hs-varop'>.</span><span class='hs-conid'>Conversions</span>
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<a name="line-11"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Typeable</span>
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<a name="line-12"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Network</span><span class='hs-varop'>.</span><span class='hs-conid'>HTTP</span><span class='hs-varop'>.</span><span class='hs-conid'>Types</span>
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<a name="line-13"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Network</span><span class='hs-varop'>.</span><span class='hs-conid'>Wai</span>
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<a name="line-14"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Servant</span><span class='hs-varop'>.</span><span class='hs-conid'>Server</span>
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<a name="line-15"></a>
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<a name="line-16"></a><a name="HasServer"></a><span class='hs-comment'>-- | Endpoint for simple GET requests. Serves the result as JSON.</span>
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<a name="line-17"></a><a name="HasServer"></a><span class='hs-comment'>--</span>
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<a name="line-18"></a><a name="HasServer"></a><span class='hs-comment'>-- Example:</span>
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<a name="line-19"></a><a name="HasServer"></a><span class='hs-comment'>--</span>
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<a name="line-20"></a><a name="HasServer"></a><span class='hs-comment'>-- > type MyApi = "books" :> Get [Book]</span>
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<a name="line-21"></a><a name="HasServer"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Get</span> <span class='hs-varid'>a</span>
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<a name="line-22"></a> <span class='hs-keyword'>deriving</span> <span class='hs-conid'>Typeable</span>
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<a name="line-23"></a>
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<a name="line-24"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- | When implementing the handler for a 'Get' endpoint,</span>
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<a name="line-25"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- just like for 'Servant.API.Delete.Delete', 'Servant.API.Post.Post'</span>
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<a name="line-26"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- and 'Servant.API.Put.Put', the handler code runs in the</span>
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<a name="line-27"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- @EitherT (Int, String) IO@ monad, where the 'Int' represents</span>
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<a name="line-28"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- the status code and the 'String' a message, returned in case of</span>
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<a name="line-29"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- failure. You can quite handily use 'Control.Monad.Trans.EitherT.left'</span>
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<a name="line-30"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- to quickly fail if some conditions are not met.</span>
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<a name="line-31"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>--</span>
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<a name="line-32"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- If successfully returning a value, we just require that its type has</span>
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<a name="line-33"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- a 'ToJSON' instance and servant takes care of encoding it for you,</span>
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<a name="line-34"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-comment'>-- yielding status code 200 along the way.</span>
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<a name="line-35"></a><a name="instance%20HasServer%20(Get%20result)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ToJSON</span> <span class='hs-varid'>result</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>HasServer</span> <span class='hs-layout'>(</span><span class='hs-conid'>Get</span> <span class='hs-varid'>result</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
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<a name="line-36"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Server</span> <span class='hs-layout'>(</span><span class='hs-conid'>Get</span> <span class='hs-varid'>result</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>EitherT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span> <span class='hs-conid'>IO</span> <span class='hs-varid'>result</span>
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<a name="line-37"></a> <span class='hs-varid'>route</span> <span class='hs-conid'>Proxy</span> <span class='hs-varid'>action</span> <span class='hs-varid'>request</span> <span class='hs-varid'>respond</span>
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<a name="line-38"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>null</span> <span class='hs-layout'>(</span><span class='hs-varid'>pathInfo</span> <span class='hs-varid'>request</span><span class='hs-layout'>)</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>requestMethod</span> <span class='hs-varid'>request</span> <span class='hs-varop'>==</span> <span class='hs-varid'>methodGet</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
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<a name="line-39"></a> <span class='hs-varid'>e</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>runEitherT</span> <span class='hs-varid'>action</span>
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<a name="line-40"></a> <span class='hs-varid'>respond</span> <span class='hs-varop'>.</span> <span class='hs-varid'>succeedWith</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>e</span> <span class='hs-keyword'>of</span>
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<a name="line-41"></a> <span class='hs-conid'>Right</span> <span class='hs-varid'>output</span> <span class='hs-keyglyph'>-></span>
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<a name="line-42"></a> <span class='hs-varid'>responseLBS</span> <span class='hs-varid'>ok200</span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-str'>"Content-Type"</span><span class='hs-layout'>,</span> <span class='hs-str'>"application/json"</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-layout'>(</span><span class='hs-varid'>encode</span> <span class='hs-varid'>output</span><span class='hs-layout'>)</span>
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<a name="line-43"></a> <span class='hs-conid'>Left</span> <span class='hs-layout'>(</span><span class='hs-varid'>status</span><span class='hs-layout'>,</span> <span class='hs-varid'>message</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span>
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<a name="line-44"></a> <span class='hs-varid'>responseLBS</span> <span class='hs-layout'>(</span><span class='hs-varid'>mkStatus</span> <span class='hs-varid'>status</span> <span class='hs-layout'>(</span><span class='hs-varid'>cs</span> <span class='hs-varid'>message</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-conid'>[]</span> <span class='hs-layout'>(</span><span class='hs-varid'>cs</span> <span class='hs-varid'>message</span><span class='hs-layout'>)</span>
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<a name="line-45"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>null</span> <span class='hs-layout'>(</span><span class='hs-varid'>pathInfo</span> <span class='hs-varid'>request</span><span class='hs-layout'>)</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>requestMethod</span> <span class='hs-varid'>request</span> <span class='hs-varop'>/=</span> <span class='hs-varid'>methodGet</span> <span class='hs-keyglyph'>=</span>
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<a name="line-46"></a> <span class='hs-varid'>respond</span> <span class='hs-varop'>$</span> <span class='hs-varid'>failWith</span> <span class='hs-conid'>WrongMethod</span>
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<a name="line-47"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>respond</span> <span class='hs-varop'>$</span> <span class='hs-varid'>failWith</span> <span class='hs-conid'>NotFound</span>
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</pre></body>
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