364 lines
10 KiB
C
364 lines
10 KiB
C
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/**
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*
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* @file Criteria.h
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* @author An Tao
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*
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* Copyright 2018, An Tao. All rights reserved.
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* https://github.com/an-tao/drogon
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* Use of this source code is governed by a MIT license
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* that can be found in the License file.
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*
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* Drogon
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*
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*/
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#pragma once
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#include <drogon/exports.h>
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#include <drogon/orm/SqlBinder.h>
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#include <drogon/utils/apply.h>
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#include <assert.h>
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#include <memory>
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#include <string>
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#include <tuple>
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#include <type_traits>
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namespace Json
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{
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class Value;
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}
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namespace drogon
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{
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namespace orm
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{
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enum class CompareOperator
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{
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EQ,
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NE,
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GT,
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GE,
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LT,
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LE,
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Like,
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NotLike,
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In,
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NotIn,
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IsNull,
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IsNotNull
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};
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/**
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* @brief Wrapper for custom SQL string
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*/
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struct CustomSql
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{
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explicit CustomSql(std::string content) : content_(std::move(content))
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{
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}
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std::string content_;
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};
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/**
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* @brief User-defined literal to convert a string to CustomSql
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*/
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inline CustomSql operator""_sql(const char *str, size_t)
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{
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return CustomSql(str);
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}
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/**
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* @brief this class represents a comparison condition.
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*/
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class DROGON_EXPORT Criteria
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{
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public:
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/**
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* @brief Check if the condition is empty.
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*
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* @return true means the condition is not empty.
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* @return false means the condition is empty.
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*/
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explicit operator bool() const
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{
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return !conditionString_.empty();
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}
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/**
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* @brief return the condition string in SQL.
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*
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* @return std::string
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*/
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std::string criteriaString() const
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{
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return conditionString_;
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}
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/**
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* @brief Construct a new custom Criteria object
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*
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* @param sql The SQL statement to be executed.
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* @param args The parameters to be passed to the placeholders.
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*
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* @note
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*
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* Use $? as placeholders in the SQL statement.
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*
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* Be careful that the placeholders are not the same as the ones in
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* functions such as drogon::orm::DbClient::execSqlAsync. Which means you
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* couldn't use numeric placeholders such as $1, $2 to represent the order
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* of the arguments.
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*
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* The arguments should be in the same order as the placeholders.
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*
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*/
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template <typename... Arguments>
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explicit Criteria(const CustomSql &sql, Arguments &&...args)
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{
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conditionString_ = sql.content_;
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outputArgumentsFunc_ =
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[args = std::make_tuple(std::forward<Arguments>(args)...)](
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internal::SqlBinder &binder) mutable {
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return apply(
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[&binder](auto &&...args) {
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(void)std::initializer_list<int>{
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(binder << std::forward<Arguments>(args), 0)...};
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},
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std::move(args));
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};
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}
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template <typename... Arguments>
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explicit Criteria(CustomSql &&sql, Arguments &&...args)
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{
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conditionString_ = std::move(sql.content_);
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outputArgumentsFunc_ =
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[args = std::make_tuple(std::forward<Arguments>(args)...)](
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internal::SqlBinder &binder) mutable {
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return apply(
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[&binder](auto &&...args) {
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(void)std::initializer_list<int>{
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(binder << std::forward<Arguments>(args), 0)...};
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},
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std::move(args));
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};
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}
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/**
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* @brief Construct a new Criteria object
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*
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* @tparam T the type of the object to be compared with.
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* @param colName The name of the column.
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* @param opera The type of the comparison.
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* @param arg The object to be compared with.
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*/
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template <typename T>
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Criteria(const std::string &colName, const CompareOperator &opera, T &&arg)
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{
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assert(opera != CompareOperator::IsNotNull &&
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opera != CompareOperator::IsNull);
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conditionString_ = colName;
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switch (opera)
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{
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case CompareOperator::EQ:
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conditionString_ += " = $?";
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break;
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case CompareOperator::NE:
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conditionString_ += " != $?";
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break;
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case CompareOperator::GT:
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conditionString_ += " > $?";
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break;
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case CompareOperator::GE:
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conditionString_ += " >= $?";
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break;
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case CompareOperator::LT:
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conditionString_ += " < $?";
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break;
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case CompareOperator::LE:
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conditionString_ += " <= $?";
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break;
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case CompareOperator::Like:
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conditionString_ += " like $?";
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break;
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case CompareOperator::NotLike:
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conditionString_ += " not like $?";
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break;
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default:
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break;
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}
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outputArgumentsFunc_ =
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[arg = std::forward<T>(arg)](internal::SqlBinder &binder) {
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binder << arg;
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};
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}
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template <typename T>
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Criteria(const std::string &colName,
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const CompareOperator &opera,
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const std::vector<T> &args)
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{
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const auto argsSize = args.size();
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assert(((opera == CompareOperator::In) ||
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(opera == CompareOperator::NotIn)) &&
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(argsSize > 0));
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if (opera == CompareOperator::In)
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{
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conditionString_ = colName + " in (";
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}
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else if (opera == CompareOperator::NotIn)
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{
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conditionString_ = colName + " not in (";
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}
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for (size_t i = 0; i < argsSize; ++i)
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{
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if (i < (argsSize - 1))
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conditionString_.append("$?,");
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else
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conditionString_.append("$?");
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}
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conditionString_.append(")");
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outputArgumentsFunc_ = [args](internal::SqlBinder &binder) {
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for (auto &arg : args)
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{
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binder << arg;
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}
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};
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}
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template <typename T>
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Criteria(const std::string &colName,
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const CompareOperator &opera,
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std::vector<T> &&args)
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{
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const auto argsSize = args.size();
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assert(((opera == CompareOperator::In) ||
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(opera == CompareOperator::NotIn)) &&
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(argsSize > 0));
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if (opera == CompareOperator::In)
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{
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conditionString_ = colName + " in (";
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}
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else if (opera == CompareOperator::NotIn)
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{
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conditionString_ = colName + " not in (";
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}
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for (size_t i = 0; i < argsSize; ++i)
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{
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if (i < (argsSize - 1))
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conditionString_.append("$?,");
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else
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conditionString_.append("$?");
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}
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conditionString_.append(")");
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outputArgumentsFunc_ =
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[args = std::move(args)](internal::SqlBinder &binder) {
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for (auto &arg : args)
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{
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binder << arg;
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}
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};
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}
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template <typename T>
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Criteria(const std::string &colName,
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const CompareOperator &opera,
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std::vector<T> &args)
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: Criteria(colName, opera, (const std::vector<T> &)args)
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{
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}
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/**
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* @brief Construct a new Criteria object presenting a equal expression
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*
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* @tparam T The type of the object to be equal to.
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* @param colName The name of the column.
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* @param arg The object to be equal to.
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*/
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template <typename T>
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Criteria(const std::string &colName, T &&arg)
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: Criteria(colName, CompareOperator::EQ, std::forward<T>(arg))
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{
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}
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/**
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* @brief Construct a new Criteria object presenting a expression without
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* parameters.
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*
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* @param colName The name of the column.
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* @param opera The type of the comparison. it must be one of the following:
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* @code
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CompareOperator::IsNotNull
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CompareOperator::IsNull
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@endcode
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*/
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Criteria(const std::string &colName, const CompareOperator &opera)
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{
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assert(opera == CompareOperator::IsNotNull ||
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opera == CompareOperator::IsNull);
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conditionString_ = colName;
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switch (opera)
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{
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case CompareOperator::IsNull:
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conditionString_ += " is null";
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break;
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case CompareOperator::IsNotNull:
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conditionString_ += " is not null";
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break;
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default:
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break;
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}
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}
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Criteria(const std::string &colName, CompareOperator &opera)
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: Criteria(colName, (const CompareOperator &)opera)
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{
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}
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Criteria(const std::string &colName, CompareOperator &&opera)
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: Criteria(colName, (const CompareOperator &)opera)
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{
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}
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/**
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* @brief Construct a new Criteria object
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*
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* @param json A json object representing the criteria
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* @note the json object must be a array of three items, the first is the
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* name of the field, the second is the comparison operator and the third is
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* the value to be compared.
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* The valid operators are "=","<",">","<=",">=","!=","in"
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* for example:
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* ["id","=",1] means 'id = 1'
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* ["id","!=",null] means 'id is not null'
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* ["user_name","in",["Tom","Bob"]] means 'user_name in ('Tom', 'Bob')'
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* ["price","<",1000] means 'price < 1000'
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*/
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explicit Criteria(const Json::Value &json) noexcept(false);
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Criteria() = default;
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/**
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* @brief Output arguments to the SQL binder object.
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*
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* @param binder The SQL binder object.
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* @note This method must be called by drogon.
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*/
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void outputArgs(internal::SqlBinder &binder) const
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{
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if (outputArgumentsFunc_)
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outputArgumentsFunc_(binder);
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}
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private:
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friend DROGON_EXPORT const Criteria operator&&(Criteria cond1,
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Criteria cond2);
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friend DROGON_EXPORT const Criteria operator||(Criteria cond1,
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Criteria cond2);
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std::string conditionString_;
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std::function<void(internal::SqlBinder &)> outputArgumentsFunc_;
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}; // namespace orm
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DROGON_EXPORT const Criteria operator&&(Criteria cond1, Criteria cond2);
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DROGON_EXPORT const Criteria operator||(Criteria cond1, Criteria cond2);
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} // namespace orm
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} // namespace drogon
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