我使用Microsoft.Data.Odata
(5.6)运行以下查询:
IEnumerable<Service> services = context.Services.Expand(ServiceQueryExpansion)
.Where(c =>
(serviceNames.Any(s => s.Equals(
c.ServiceName, StringComparison.OrdinalIgnoreCase))))
serviceNames是IEnumerable of string
尝试上述查询时出现以下错误:
Error translating Linq expression to URI: The source parameter for the 'Any' method has to be either a navigation or a collection property.
如何解决此问题?
答案 0 :(得分:3)
我知道这很有趣也很令人兴奋(讽刺),但你可以像这样动态构建你的Where表达式:
var serviceNames = new string[] { "SERVICE1","SERVICE2"};
Expression<Func<Service,bool>> inList = v => false;
var parameter = inList.Parameters[0];
var propertyExpression = Expression.Property(parameter,"ServiceName");
foreach (var serviceName in serviceNames)
{
var body = inList.Body;
var constantExpression = Expression.Constant(serviceName);
var equalityExpression = Expression.Equal(propertyExpression,constantExpression);
body = Expression.OrElse(body,equalityExpression);
inList = Expression.Lambda<Func<Service, bool>>(body, parameter);
}
IEnumerable<Service> services = context.Services.Expand(ServiceQueryExpansion)
.Where(inList);
此方法从列表中构建一个自定义where子句,类似于(v =&gt; v.ServiceName ==“Service1”|| v.ServiceName ==“Service2”|| v.ServiceName ==“Service3”)
您可以按照我的博客http://coding.grax.com/2013/07/filter-pattern-for-linq-query-filter.html中的说明将此逻辑封装到自定义“WhereContains(yourListHere)”自定义过滤器扩展方法中。
答案 1 :(得分:0)
你可以写:
var services = context.Services.Expand(ServiceQueryExpansion).AsEnumerable()
.Where(c => serviceNames.Contains(c.ServiceName));
但它将下载整个服务集合。 或者:
var services = serviceNames.SelectMany(s=>
context.Services.Expand(ServiceQueryExpansion).Where(c=> c.ServicaName == s));
这将创建N个请求。
我不知道在Linq到OData的任何更好的方法。
答案 2 :(得分:0)
我所做的是应用我可以使用的过滤器,然后列出,然后在本地获得结果后再制作另一个过滤器。
var services = context.Services.Expand(ServiceQueryExpansion).ToList();
services = services.Where(s => serviceNames.Any(n => n.ServiceName.Equals(s, StringComparison.OrdinalIgnoreCase)));
如果您有多条记录不需要通过网络,这不是最佳选择。
另一种选择是创建数据服务操作。
[WebGet]
public IQueryable<Service> GetServicesByServiceName(string serviceNames)
{
var serviceNamesArray = serviceNames.Split(',');
var ctx = YourContext();
return ctx.Services.Include("ServiceQueryExpansion").Where(s => serviceNamesArrays.Any(n => s.ServiceName.Equals(n, StringComparison.OrdinalIgnoreCase))).AsQueryable();
}