业务场景：
在 ASP.NET Core 项目中，所有的代码都是骆驼命名，比如userName, UserName，但对于 WebApi 项目来说，因为业务需要，一些请求、查询和响应参数的格式需要转换，比如转换成下划线命名（又称为snake case），比如user_name。
具体实现：
请求和响应参数格式转换（请求具体是非get请求，响应参数一般为json），ASP.NET Core 实现很简单，Startup只需要下面配置代码：
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc()
.AddJsonOptions(options => options.SerializerSettings.ContractResolver = new DefaultContractResolver()
{
NamingStrategy = new SnakeCaseNamingStrategy()
});
}查询参数实现比较麻烦点（具体为get请求，比如users?user_name=xishuai&user_id=1），实现代码：
public class RewriteQueryStringMiddleware
{
private readonly RequestDelegate _next;
//Your constructor will have the dependencies needed for database access
public RewriteQueryStringMiddleware(RequestDelegate next)
{
_next = next;
}
public async Task Invoke(HttpContext context)
{
var query = context.Request.QueryString;
if (query.HasValue)
{
var parms = string.Join("&", query.Value.TrimStart('?').Split('&').Select(s =>
{
var kv = s.Split('=');
var k = kv[0].Replace("_", "");
var v = kv[1];
return $"{k}={v}";
}));
QueryString newQuery = new QueryString($"?{parms}");
context.Request.QueryString = newQuery;
}
//Let the next middleware (MVC routing) handle the request
//In case the path was updated, the MVC routing will see the updated path
await _next.Invoke(context);
}
}
public static class RewriteQueryStringExtensions
{
public static IApplicationBuilder UseRewriteQueryString(this IApplicationBuilder builder)
{
return builder.UseMiddleware<RewriteQueryStringMiddleware>();
}
}实现原理就是截获请求，并对QueryString转换和重写，Startup中添加配置：
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
app.UseRewriteQueryString();
}
本文转自田园里的蟋蟀博客园博客，原文链接：http://www.cnblogs.com/xishuai/p/snake_case-json-with-asp-net-core-webapi.html，如需转载请自行联系原作者
