Dapper DynamicParameters object 可以像参数字典一样枚举吗？

Question

我知道我可以使用 ParameterDirection 和 Dapper.DynamicParameters:

var parameters = new DynamicParameters();
parameters.Add("iparam", 42);
parameters.Add("oparam", null, DbType.Int32, ParameterDirection.Output);
connection.Execute(sql, parameters);

但是我可以在使用 Dictionary<string, object> 时这样做吗？

var parameters = new Dictionary<string, object>();
parameters.Add("iparam", 42);
parameters.Add("oparam", /* ??? */ );
connection.Execute(sql, parameters);

或者，我如何遍历 DynamicParameters 以获得参数名称和值？

原标题：

Can a Dapper parameter with ParameterDirection be added using a dictionary?

Answer 1

这似乎是 Dapper 中的一个错误。这已确认在最新的 NuGet 包中工作：

foreach (var paramName in parameters.ParameterNames)
{
    var value = ((SqlMapper.IParameterLookup)parameters)[paramName];
}

但是，它有点冗长。在本地使用 Dapper source (not a NuGet package), I was able to run this code without error (As of writing that's commit b77e53):

foreach (var paramName in parameters.ParameterNames)
{
    var value = parameters.Get<dynamic>(paramName);
}

根据, it still throws an exception, which leads me to believe the patch hasn't made it into NuGet yet. The commit which fixes Get<dynamic> is here

Answer 2

DynamicParameters 对象在每次追加时可以包含多个部分。所以像上面的答案一样遍历 ParameterNames（它将是空的）是不够的。

public static Dictionary<string, object> ToParametersDictionary(this DynamicParameters dynamicParams)
{
    var argsDictionary = new Dictionary<String, Object>();
    var iLookup = (SqlMapper.IParameterLookup) dynamicParams;
    //if (dynamicParams.ParameterNames.Any())
    //{
        // read the parameters added via dynamicParams.Add("NAME", value)
        foreach (var paramName in dynamicParams.ParameterNames)
        {
            var value = iLookup[paramName];
            argsDictionary.Add(paramName, value);
        }
    //}
    //else
    //{
        // read the "templates" field containing dynamic parameters section added
        // via dynamicParams.Add(new {PARAM_1 = value1, PARAM_2 = value2});
        var templates = dynamicParams.GetType().GetField("templates", BindingFlags.NonPublic | BindingFlags.Instance);
        if (templates != null)
        {
            var list = templates.GetValue(dynamicParams) as List<Object>;
            if (list != null)
            {
                // add properties of each dynamic parameters section
                foreach (var objProps in list.Select(obj => obj.GetPropertyValuePairs().ToList()))
                {
                    objProps.ForEach(p => argsDictionary.Add(p.Key, p.Value));
                }
            }
        }
    }
    return argsDictionary;
}

并且GetPropertyValuePairs(..)是

public static Dictionary<string, object> GetPropertyValuePairs(this object obj, String[] hidden = null)
{
    var type = obj.GetType();
    var pairs = hidden == null
        ? type.GetProperties()
            .DistinctBy(propertyInfo => propertyInfo.Name)
            .ToDictionary(
                propertyInfo => propertyInfo.Name,
                propertyInfo => propertyInfo.GetValue(obj, null))
        : type.GetProperties()
            .Where(it => !hidden.Contains(it.Name))
            .DistinctBy(propertyInfo => propertyInfo.Name)
            .ToDictionary(
                propertyInfo => propertyInfo.Name,
                propertyInfo => propertyInfo.GetValue(obj, null));
    return pairs;
}

public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
    var seenKeys = new HashSet<TKey>();
    return source.Where(element => seenKeys.Add(keySelector(element)));
}

Dapper DynamicParameters object 可以像参数字典一样枚举吗？

Can a Dapper DynamicParameters object be enumerated like a dictionary of parameters?

c#

dapper

.net-4.5