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web api 2 学习笔记 (Odata basic)

开发时不同状况下的方案 :

1. 权限管理 , 在expand时要确保被expand的资源是无需访问权限的，因为expand在后台很难做where, 所以针对有权限要求的资源就不允许expand而改用另一些接口，比如 members(5)/orders 而不是members + expand orders

1.1 针对不同权限能expand的column不同也是非常难搞的，基本上就是要在controller 通过分析ODataQueryOptions.selectExpand 才能处理.

2.级联删除，最好是通过sql来做级联删除，除非我们需要做历史垃圾桶记入才用EF实现，EF的级联是需要加载所有的子孙资源出来，才能透过删除parent自能的删除子层,性能不佳.

3.post model validation & logic fill , 简单就是用自带validation的，困难的就开方法, logic fill 也是开方法

4.column 不允许修改就透过开方法拦截saveChange set isModified = false 来实现。

5.并发问题，基本上都是采用乐观并发，就是说大家都可以随时改，但是最终save的时候可能会error。

主要就是看新value是依据哪些资源来确定的，我们就必须确保那些资源都是没人修改过的。(大部分情况下都是依据资源本身，所以EF也只支持到那，但是实际情况下可能会更复杂)

insert也是会有并发问题的，而且并不一定是unique。只要一个action依赖其它资源，在执行action时就要确保依赖的资源是没被修改过的。

返回 HttpResponseMessage

public async Task<HttpResponseMessage> post(Product product)
{  
    db.products.Add(product);
    await db.SaveChangesAsync();
    var response = Request.CreateResponse<Product>(HttpStatusCode.OK, product);
    response.Headers.Add("custome", "haha");            
    return response; 
}

Put [ODataRoute("({id})")]public async Task<IHttpActionResult> put(int id, Color color, ODataQueryOptions<Color> options){

if (options.IfMatch != null && !(options.IfMatch.ApplyTo(db.colors.Where(c => c.id == id)) as IQueryable<Color>).Any())
    {
        //concurrency
    }
    else
    {

    }
    color.id = id;
    db.Entry(color).State = EntityState.Modified;
    db.Entry(companySQL).CurrentValues.SetValues(companyDTO);
    db.Entry(companySQL).OriginalValues["rowVersion"] = companyDTO.rowVersion;
    db.Entry(color).Property(c => c.Products_id).IsModified = false;
    await db.SaveChangesAsync();
    this.detachedAllEntity();
    return Ok(color);

前台的request 要加header "if-Match": resource["@odata.etag"]

Get navigationProps

[ODataRoute("({id})/product")]
[ODataRoute("({id})/sizes")]
public async Task<IHttpActionResult> getProp(int id)
{
    //future: 没有实现动态的原因是因为目前没办法做好返回的类型,简单返回object的话,odata to json 时没办法匹配到EDM
    var navigationPropName = this.Url.Request.RequestUri.Segments.Last();
    switch (navigationPropName)
    {
        case "sizes":
            return Ok(db.colors.Where(c => c.id == id).SelectMany(c => c.sizes));
        case "product":
            return Ok((await db.colors.Include(c => c.product).FirstOrDefaultAsync(c => c.id == id)).product);
        default:
            return BadRequest();
    }
}

Single result

public SingleResult<LoginPerson> getLoginPersonByUserObject()
{
    if (!(User is LoginPerson)) throw new AjaxEx("noCookie");
    LoginPerson LoginPerson = User as LoginPerson;
    IQueryable<LoginPerson> query = db.LoginPersons.Include(l => l.roles).Include(l => l.accountBindings).Where(l => l.id == LoginPerson.id);
    return SingleResult.Create<LoginPerson>(query);
}

Get

[ODataRoute("")]
[EnableQuery(AllowedQueryOptions = WebApiConfig.ALLOW_QUERY | AllowedQueryOptions.Expand, MaxExpansionDepth = 5)]
public IQueryable<Employer> get()
{
    return db.Employers;
}

Get + 权限管理

refer : http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/supporting-odata-query-options

动态 EnableQuery

不是用 options.ApplyTo , 因为他会破坏 $expand 和 $select，以后可能可以. refer : http://stackoverflow.com/questions/18879779/select-and-expand-break-odataqueryoptions-how-to-fix

[ODataRoute("")]
[EnableQuery] //开放到完
public IQueryable<Employer> get(ODataQueryOptions<Employer> options)
{
    //动态验证          
    //base on 不同权限设置 ODataValidationSettings
    var settings = new ODataValidationSettings()
    { 
        AllowedQueryOptions = WebApiConfig.ALLOW_QUERY
    };
    //一定要用 catch 
    try
    {
        options.Validate(settings);
    }
    catch (ODataException ex)
    {
        throw new AjaxEx(ex.Message); 
    }             
    return db.Employers; 
}

many to many RPC

public class UpdateMMCategorysBody
{
    public List<int> removeIds { get; set; }
    public List<int> addIds { get; set; }
}
[ODataRoute("({id})/RPC.updateMMCategorys")]
public async Task<IHttpActionResult> updateMMCategorys(int id, UpdateMMCategorysBody data)
{
    var product = await db.products.Include(p => p.categorys).FirstOrDefaultAsync(p => p.id == id);
    if (product == null) throw new AjaxEx("productNotFound");
    for (int i = product.categorys.Count - 1; i >= 0; i--)
    {
        var category = product.categorys[i];
        if (data.removeIds.Contains(category.id))
        {
            product.categorys.Remove(category);
        }
    }
    var categoryForAdds = await db.categorys.Where(c => data.addIds.Contains(c.id)).ToListAsync();
    if (categoryForAdds.Count != data.addIds.Count) throw new AjaxEx("categoryNotFound");
    categoryForAdds.ForEach(c =>
    {
        product.categorys.Add(c);
    });
    await db.SaveChangesAsync();
    return Ok("ok");
}

BaseController :

public class BaseController : ODataController
{
    protected DB db = DB.Sharing.getDb();
    protected override void Dispose(bool disposing)
    {
        DB.Sharing.disposeDb();
        DB.Sharing.disposeTansaction();
        base.Dispose(disposing);
    }
    protected void detachedAllEntity()
    {
        var manager = ((IObjectContextAdapter)this.db).ObjectContext.ObjectStateManager;
        var objectStateEntries = manager.GetObjectStateEntries(EntityState.Added | EntityState.Deleted | EntityState.Modified | EntityState.Unchanged);
        foreach (var objectStateEntry in objectStateEntries)
        {
            db.Entry(objectStateEntry.Entity).State = EntityState.Detached;
        }
    }
}

POST with model validation

refer :http://www.asp.net/web-api/overview/formats-and-model-binding/model-validation-in-aspnet-web-api

refer : https://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.aspx

[ODataRoute("")]
public async Task<IHttpActionResult> post(Employer employer)
{
    if (ModelState.IsValid)
    {
        db.Employers.Add(employer);
        await db.SaveChangesAsync();
        return Ok(employer);
    }
    else
    {
        return BadRequest(ModelState);
    }           
}

获取完整的 restful hateoas response

note : builder.EntitySet<Class>("Classs"); <-每一个class都要写，不然expand的话会error哦


$http({
    url: "//localhost:11207/api/Employers",
    headers : {
        Accept: "application/json;odata.metadata=full"
    }, 
    method : "GET"
});

常用的 url 写法

/api/Products?$filter=colors/any(c:c/id gt 0); 找出有color的product

(本来应该用$count的而不是 gt 0, but refer http://forums.asp.net/t/2070250.aspx Web+API+2+OData+v4+filter+Count+of+a+Collection)

/api/Products?$filter=not(colors/any(c:c/id gt 0)); 找出没有color的product

/api/Colors?$filter=type eq EFDB.ColorType'a'; 　　filter by Enum

/api/comments?$filter=user/EFDB.Salesman/salesmanColumn eq 'abc' filter 抽象类和属性

/api/EmployerTicketSlots?$filter=EFDB.EmployerTicketSlot/id gt 0 , filter抽象类本来应该不是用 gt 0，but 暂时没找到正规写法

for expand : /api/Singles?$expand=abstracts($expand=EFDB.AA/childs,EFDB.BB/childs) expand 派生类和子层, 可以同时多种派生类哦

/api/Products?createDt gt 2015-10-10T08:00:00.0000000+08:00 filter datetimeoffset，用UTC也可以, js : new Date().toJSON();

/api/Products?$filter=contains(code,'mk100')) filter like

/api/Products?$expand=colors($filter=ID eq 5;$expand=sizes;$orderby=ID desc;$select=name); nested expand

/api/Products?$expand=* 全部都expand, 只是 1 层而已噢

/api/people?$expand=upline($level=2) 直接拿2层upline

/api/people?$expand=directMembers($count=true) $expand也可以$count哦

更新 : 2016-02-12

OData 的继承顺序

parent constructor -> child construtor -> child ExecuteAsync -> child Initialize

constructor 阶段request is null, child ExecuteAsync and Initialize 内部就可以调用base了,顺序就不太重要了.

更新 : 2016-06-03

http://docs.oasis-open.org/odata/odata/v4.0/errata02/os/complete/part1-protocol/odata-v4.0-errata02-os-part1-protocol-complete.html#_The_$format_System

http://docs.oasis-open.org/odata/odata/v4.0/odata-v4.0-part2-url-conventions.html

http://docs.oasis-open.org/odata/odata/v4.0/odata-v4.0-part3-csdl.html

http://www.odata.org/documentation/