对于带有变量的EF Core 3.1，我有以下内容（基于halllo的GitHub注释），这些内容已链接在@ Thom Kiesewetter等人的注释中。
/// <summary>
/// SQL Extension methods to get the SQL and check correctness
/// Class can be removed with EF Core 5 (https://github.com/dotnet/efcore/issues/6482#issuecomment-587605366) (although maybe variable substitution might still be necessary if we want them inline)
/// </summary>
public static class SqlExtensions
{
private static object Private(this object obj, string privateField) => obj?.GetType().GetField(privateField, BindingFlags.Instance | BindingFlags.NonPublic)?.GetValue(obj);
private static T Private<T>(this object obj, string privateField) => (T)obj?.GetType().GetField(privateField, BindingFlags.Instance | BindingFlags.NonPublic)?.GetValue(obj);
/// <summary>
/// Gets a SQL statement from an IQueryable
/// </summary>
/// <param name="query">The query to get the SQL statement for</param>
/// <returns>Formatted SQL statement as a string</returns>
public static string ToQueryString<TEntity>(this IQueryable<TEntity> query) where TEntity : class
{
using var enumerator = query.Provider.Execute<IEnumerable<TEntity>>(query.Expression).GetEnumerator();
var relationalCommandCache = enumerator.Private("_relationalCommandCache");
var selectExpression = relationalCommandCache.Private<SelectExpression>("_selectExpression");
var factory = relationalCommandCache.Private<IQuerySqlGeneratorFactory>("_querySqlGeneratorFactory");
var relationalQueryContext = enumerator.Private<RelationalQueryContext>("_relationalQueryContext");
var sqlGenerator = factory.Create();
var command = sqlGenerator.GetCommand(selectExpression);
var parametersDict = relationalQueryContext.ParameterValues;
return SubstituteVariables(command.CommandText, parametersDict);
}
private static string SubstituteVariables(string commandText, IReadOnlyDictionary<string, object> parametersDictionary)
{
var sql = commandText;
foreach (var (key, value) in parametersDictionary)
{
var placeHolder = "@" + key;
var actualValue = GetActualValue(value);
sql = sql.Replace(placeHolder, actualValue);
}
return sql;
}
private static string GetActualValue(object value)
{
var type = value.GetType();
if (type.IsNumeric())
return value.ToString();
if (type == typeof(DateTime) || type == typeof(DateTimeOffset))
{
switch (type.Name)
{
case nameof(DateTime):
return $"'{(DateTime)value:u}'";
case nameof(DateTimeOffset):
return $"'{(DateTimeOffset)value:u}'";
}
}
return $"'{value}'";
}
private static bool IsNullable(this Type type)
{
return
type != null &&
type.IsGenericType &&
type.GetGenericTypeDefinition() == typeof(Nullable<>);
}
private static bool IsNumeric(this Type type)
{
if (IsNullable(type))
type = Nullable.GetUnderlyingType(type);
if (type == null || type.IsEnum)
return false;
return Type.GetTypeCode(type) switch
{
TypeCode.Byte => true,
TypeCode.Decimal => true,
TypeCode.Double => true,
TypeCode.Int16 => true,
TypeCode.Int32 => true,
TypeCode.Int64 => true,
TypeCode.SByte => true,
TypeCode.Single => true,
TypeCode.UInt16 => true,
TypeCode.UInt32 => true,
TypeCode.UInt64 => true,
_ => false
};
}
}
也许这并不能替代所有类型，但是大多数都涵盖了。随意扩展。
