';参数';f';未绑定到指定的LINQ to Entities查询表达式';中;
本文关键字:Entities to 查询 表达式 LINQ 查询表 参数 绑定 | 更新日期: 2023-09-27 18:30:12
使用EF 6。有人能告诉我我做错了什么吗?
public List<SearchResult> SearchDocuments(List<SearchCriteria> searchCriterias)
{
List<SearchResult> results = new List<SearchResult>();
var fieldSettings = LoadCoordinateSystemFieldSettings(searchCriterias);
using (var context = CreateContext())
{
var tractsQuery = PredicateBuilder.False<v_UploadByTract_ActiveUploads>();
foreach (var searchCriteria in searchCriterias)
{
var queryBuilder = PredicateBuilder.True<v_UploadByTract_ActiveUploads>();
// tractsQuery
if (searchCriteria.StateAPI.HasValue)
queryBuilder = queryBuilder.And(a => a.StateAPI == searchCriteria.StateAPI.Value);
if (searchCriteria.CountyAPI.HasValue)
queryBuilder = queryBuilder.And(a => a.CountyAPI == searchCriteria.CountyAPI.Value);
// ...
// ... many more similar IF-ANDs
// ...
tractsQuery = tractsQuery.Or(queryBuilder);
}
var searchQuery = context.v_UploadByTract_ActiveUploads.AsExpandable().Where(tractsQuery).ToList();
//.Select(a => SearchResult.Create(a));
//results.AddRange(searchQuery.ToList());
}
return results;
}
public static class PredicateBuilder
{
public static Expression<Func<T, bool>> True<T>() { return f => true; }
public static Expression<Func<T, bool>> False<T>() { return f => false; }
public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expr1,
Expression<Func<T, bool>> expr2)
{
var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
return Expression.Lambda<Func<T, bool>>
(Expression.OrElse(expr1.Body, invokedExpr), expr1.Parameters);
}
public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expr1,
Expression<Func<T, bool>> expr2)
{
var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
return Expression.Lambda<Func<T, bool>>
(Expression.AndAlso(expr1.Body, invokedExpr), expr1.Parameters);
}
}
C#谓词生成器实体:参数';f';未绑定在指定的LINQ to Entities查询表达式中
对于其他在谷歌上搜索到这里的人,我的解决方案是在将修改后的表达式返回到表达式树之前Visit
。这绑定了lambda参数。