我有一个方法可以帮助在客户端动态构建查询:
public virtual IList<TEntity> Fill(Expression<Func<TEntity, bool>> filter = null,
Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
string includeProperties = "")
{
includeProperties = includeProperties ?? "";
var qctx = new TQueryContext
{
QueryType = filter == null ? CommonQueryType.FillAll : CommonQueryType.FillWhere,
Filter = filter,
OrderBy = orderBy
};
qctx.Includes.AddRange(includeProperties.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries));
_detachedServerRepo.Read(qctx);
return qctx.Entities;
}
我想将 qctx
发送到可能在另一台机器上的服务器仓库。由于 TQueryContext
将从 QueryContextBase
中键入,部分定义如下,因此我无法对其进行序列化。
public class QueryContextBase<TEntity, TKey>
where TEntity : StateTrackedObject
where TKey : IEquatable<TKey>
{
public TKey ID { get; set; }
public string Alf { get; set; }
public List<TEntity> Entities { get; set; }
public List<string> Includes { get; set; }
public Expression<Func<TEntity, bool>> Filter { get; set; }
public Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> OrderBy { get; set; }
}
我如何创建与 Filter
和 OrderBy
类似的属性,以便我可以序列化它们,然后在服务器存储库中构建查询,如下所示:
protected override void FillWhere(TQueryContext qctx)
{
qctx.Entities.AddRange(this.Fill(qctx.Filter, qctx.OrderBy,
qctx.GetIncludesAsString()));
}
protected override void FillAll(TQueryContext qctx)
{
qctx.Entities.AddRange(this.Fill(null, qctx.OrderBy, qctx.GetIncludesAsString()));
}
public virtual IEnumerable<TEntity> Fill(Expression<Func<TEntity, bool>> filter = null,
Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>> orderBy = null,
string includeProperties = "")
{
includeProperties = includeProperties ?? "";
try
{
IQueryable<TEntity> querySet = DbSet;
if (filter != null)
{
querySet = querySet.Where(filter);
}
foreach (var includeProperty in includeProperties.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries))
{
querySet = querySet.Include(includeProperty.Trim());
}
return (orderBy == null) ? querySet.ToList() : orderBy(querySet).ToList();
}
catch (Exception ex)
{
return ex.ThrowDalException<IEnumerable<TEntity>>(OperationType.Read, ex.Message, ex);
}
}
最佳答案
您不想重新发明轮子是对的。查看Serialize.Linq .
你可以用这个库解决你的问题,如下所示:
在您的客户端仓库中:
public virtual IList<TEntity> Fill(Expression<Func<TEntity, bool>> filter = null,
Expression<Func<IQueryable<TEntity>,
IOrderedQueryable<TEntity>>> orderBy = null,
string includeProperties = "") {
includeProperties = includeProperties ?? "";
try
{
var qctx = new TQueryContext
{
QueryType = filter == null ? CommonQueryType.FillAll : CommonQueryType.FillWhere,
FilterNode = filter == null ? null : filter.ToExpressionNode(),
OrderByNode = orderBy == null ? null : orderBy.ToExpressionNode()
};
然后在您的 QueryContext 中添加额外的属性并转换:
public ExpressionNode FilterNode { get; set; }
public Expression<Func<TEntity, bool>> Filter
{
get {
return FilterNode == null ? null : FilterNode.ToBooleanExpression<TEntity>();
}
}
public ExpressionNode OrderByNode { get; set; }
public Expression<Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>>> OrderBy
{
get {
return OrderByNode == null ? null : OrderByNode.ToExpression<Func<IQueryable<TEntity>, IOrderedQueryable<TEntity>>>();
}
}
关于c# - 从客户端向服务器发送 lambda 表达式,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/32548662/