dapper 自定义数据库字段和代码中Model字段不一致时候的mapping方法 - 不能失败 - 博客园

Excerpt
namespace YourNamespace{ /// /// Uses the Name value of the ColumnAttribute specified, otherwise maps as usual. /// /// The type of the …

<span>namespace</span><span> YourNamespace
{
    </span><span>///</span> <span>&lt;summary&gt;</span>
    <span>///</span><span> Uses the Name value of the ColumnAttribute specified, otherwise maps as usual.
    </span><span>///</span> <span>&lt;/summary&gt;</span>
    <span>///</span> <span>&lt;typeparam name="T"&gt;</span><span>The type of the object that this mapper applies to.</span><span>&lt;/typeparam&gt;</span>
    <span>public</span> <span>class</span> ColumnAttributeTypeMapper&lt;T&gt;<span> : FallbackTypeMapper
    {
        </span><span>public</span><span> ColumnAttributeTypeMapper()
            : </span><span>base</span>(<span>new</span><span> SqlMapper.ITypeMap[]
                {
                    </span><span>new</span><span> CustomPropertyTypeMap(
                       </span><span>typeof</span><span>(T),
                       (type, columnName) </span>=&gt;<span>
                           type.GetProperties().FirstOrDefault(prop </span>=&gt;<span>
                               prop.GetCustomAttributes(</span><span>false</span><span>)
                                   .OfType</span>&lt;ColumnMappingAttribute&gt;<span>()
                                   .Any(attr </span>=&gt; attr.Name ==<span> columnName)
                               )
                       ),
                    </span><span>new</span> DefaultTypeMap(<span>typeof</span><span>(T))
                })
        {
        }
    }
    
  [AttributeUsage(AttributeTargets.Property, AllowMultiple </span>= <span>true</span><span>)]
    </span><span>public</span> <span>class</span><span> ColumnMappingAttribute : Attribute
    {
        </span><span>public</span> <span>string</span> Name { <span>get</span>; <span>set</span><span>; }
    }
 
  </span><span>public</span> <span>class</span><span> FallbackTypeMapper : SqlMapper.ITypeMap
    {
        </span><span>private</span> <span>readonly</span> IEnumerable&lt;SqlMapper.ITypeMap&gt;<span> _mappers;
 
        </span><span>public</span> FallbackTypeMapper(IEnumerable&lt;SqlMapper.ITypeMap&gt;<span> mappers)
        {
            _mappers </span>=<span> mappers;
        }
 
 
        </span><span>public</span> ConstructorInfo FindConstructor(<span>string</span><span>[] names, Type[] types)
        {
            </span><span>foreach</span> (<span>var</span> mapper <span>in</span><span> _mappers)
            {
                </span><span>try</span><span>
                {
                    ConstructorInfo result </span>=<span> mapper.FindConstructor(names, types);
                    </span><span>if</span> (result != <span>null</span><span>)
                    {
                        </span><span>return</span><span> result;
                    }
                }
                </span><span>catch</span><span> (NotImplementedException)
                {
                }
            }
            </span><span>return</span> <span>null</span><span>;
        }
 
        </span><span>public</span> SqlMapper.IMemberMap GetConstructorParameter(ConstructorInfo constructor, <span>string</span><span> columnName)
        {
            </span><span>foreach</span> (<span>var</span> mapper <span>in</span><span> _mappers)
            {
                </span><span>try</span><span>
                {
                    </span><span>var</span> result =<span> mapper.GetConstructorParameter(constructor, columnName);
                    </span><span>if</span> (result != <span>null</span><span>)
                    {
                        </span><span>return</span><span> result;
                    }
                }
                </span><span>catch</span><span> (NotImplementedException)
                {
                }
            }
            </span><span>return</span> <span>null</span><span>;
        }
 
        </span><span>public</span> SqlMapper.IMemberMap GetMember(<span>string</span><span> columnName)
        {
            </span><span>foreach</span> (<span>var</span> mapper <span>in</span><span> _mappers)
            {
                </span><span>try</span><span>
                {
                    </span><span>var</span> result =<span> mapper.GetMember(columnName);
                    </span><span>if</span> (result != <span>null</span><span>)
                    {
                        </span><span>return</span><span> result;
                    }
                }
                </span><span>catch</span><span> (NotImplementedException)
                {
                }
            }
            </span><span>return</span> <span>null</span><span>;
        }
    }
  
}</span>

<span>public</span> <span>static</span><span> IEnumerable LoadWithCustomMapping()
{
    </span><span>using</span> (<span>var</span> conn =<span> OpenDBConnection())
    {
        Dapper.SqlMapper.SetTypeMap(</span><span>typeof</span>(MyArea), <span>new</span><span> ColumnAttributeTypeMapper());
        </span><span>return</span> conn.Query(<span>"</span><span>SELECT TOP 10 CAID,CAName,En FROM CityArea</span><span>"</span><span>);
    }
}</span>

posted @ 2014-10-20 23:14 不能失败阅读(7222) 评论() 编辑收藏举报