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80 lines
2.4 KiB
C
80 lines
2.4 KiB
C
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#pragma once
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#include "ApiTypes.h"
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namespace resource_api
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{
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// C must be a type with STL like iterator, a begin() and an end() method
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// additionally a function id() which gives a unique value for every container element
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// the type of the id should be string
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// the type returned by dereferencing the iterator should have a stream operator for StreamBase
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// the stream operator must not add an element "id", this is done by the pagination handler
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template<class C>
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void handlePaginationRequest(Request& req, Response& resp, const C& data)
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{
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if(!req.isGet()){
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resp.mDebug << "unsupported method. only GET is allowed." << std::endl;
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resp.setFail();
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return;
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}
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if(data.begin() == data.end()){
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// set result type to list
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resp.mDataStream.getStreamToMember();
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resp.mDebug << "note: list is empty" << std::endl;
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return;
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}
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std::string first;
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std::string last;
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req.mStream << makeKeyValueReference("first", first) << makeKeyValueReference("last", last);
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C::iterator it_first = data.begin();
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if(first != "begin")
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{
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while(it_first != data.end() && id(*it_first) != first)
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it_first++;
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if(it_first == data.end())
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{
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resp.setFail("Error: first id did not match any element");
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return;
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}
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}
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C::iterator it_last = data.begin();
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if(last == "end")
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{
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it_last = data.end();
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}
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else
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{
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while(it_last != data.end() && id(*it_last) != last)
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it_last++;
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if(it_last == data.end())
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{
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resp.setFail("Error: last id did not match any element");
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return;
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}
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++it_last; // increment to get iterator to element after the last wanted element
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}
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int count = 0;
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for(C::iterator it = it_first; it != it_last; ++it)
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{
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StreamBase& stream = resp.mDataStream.getStreamToMember();
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stream << *it;
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stream << makeKeyValue("id", id(*it));
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// todo: also handle the case when the last element is specified and the first element is begin
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// then want to return the elements near the specified element
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count++;
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if(count > 20){
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resp.mDebug << "limited the number of returned items to 20" << std::endl;
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break;
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}
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}
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resp.setOk();
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}
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} // namespace resource_api
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