/// <summary>
/// Allows you to automatically populate a target property/field from output parameters. It actually
/// creates an InputOutput parameter, so you can still pass data in.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="target">The object whose property/field you wish to populate.</param>
/// <param name="expression">A MemberExpression targeting a property/field of the target (or descendant thereof.)</param>
/// <param name="dbType"></param>
/// <param name="size">The size to set on the parameter. Defaults to 0, or DbString.DefaultLength in case of strings.</param>
/// <returns>The DynamicParameters instance</returns>
public DynamicParameters Output <T>(T target, Expression <Func <T, object> > expression, DbType?dbType = null, int?size = null)
{
var failMessage = "Expression must be a property/field chain off of a(n) {0} instance";
failMessage = string.Format(failMessage, typeof(T).Name);
Action @throw = () => throw new InvalidOperationException(failMessage);
// Is it even a MemberExpression?
var lastMemberAccess = expression.Body as MemberExpression;
if (lastMemberAccess == null ||
(!(lastMemberAccess.Member is PropertyInfo) &&
!(lastMemberAccess.Member is FieldInfo)))
{
if (expression.Body.NodeType == ExpressionType.Convert &&
expression.Body.Type == typeof(object) &&
((UnaryExpression)expression.Body).Operand is MemberExpression)
{
// It's got to be unboxed
lastMemberAccess = (MemberExpression)((UnaryExpression)expression.Body).Operand;
}
else
{
@throw();
}
}
// Does the chain consist of MemberExpressions leading to a ParameterExpression of type T?
MemberExpression diving = lastMemberAccess;
// Retain a list of member names and the member expressions so we can rebuild the chain.
List <string> names = new List <string>();
List <MemberExpression> chain = new List <MemberExpression>();
do
{
// Insert the names in the right order so expression
// "Post.Author.Name" becomes parameter "PostAuthorName"
names.Insert(0, diving?.Member.Name);
chain.Insert(0, diving);
var constant = diving?.Expression as ParameterExpression;
diving = diving?.Expression as MemberExpression;
if (constant != null && constant.Type == typeof(T))
{
break;
}
else if (diving == null ||
(!(diving.Member is PropertyInfo) &&
!(diving.Member is FieldInfo)))
{
@throw();
}
}while (diving != null);
var dynamicParamName = string.Concat(names.ToArray());
// Before we get all emitty...
var lookup = string.Join("|", names.ToArray());
var cache = CachedOutputSetters <T> .Cache;
var setter = (Action <object, DynamicParameters>)cache[lookup];
if (setter != null)
{
goto MAKECALLBACK;
}
// Come on let's build a method, let's build it, let's build it now!
var dm = new DynamicMethod("ExpressionParam" + Guid.NewGuid().ToString(), null, new[] { typeof(object), GetType() }, true);
var il = dm.GetILGenerator();
il.Emit(OpCodes.Ldarg_0); // [object]
il.Emit(OpCodes.Castclass, typeof(T)); // [T]
// Count - 1 to skip the last member access
for (var i = 0; i < chain.Count - 1; i++)
{
var member = chain[i].Member;
if (member is PropertyInfo info)
{
var get = info.GetGetMethod(true);
il.Emit(OpCodes.Callvirt, get); // [Member{i}]
}
else // Else it must be a field!
{
il.Emit(OpCodes.Ldfld, (FieldInfo)member); // [Member{i}]
}
}
var paramGetter = GetType().GetMethod("Get", new Type[] { typeof(string) }).MakeGenericMethod(lastMemberAccess.Type);
il.Emit(OpCodes.Ldarg_1); // [target] [DynamicParameters]
il.Emit(OpCodes.Ldstr, dynamicParamName); // [target] [DynamicParameters] [ParamName]
il.Emit(OpCodes.Callvirt, paramGetter); // [target] [value], it's already typed thanks to generic method
// GET READY
var lastMember = lastMemberAccess.Member;
if (lastMember is PropertyInfo)
{
var set = ((PropertyInfo)lastMember).GetSetMethod(true);
il.Emit(OpCodes.Callvirt, set); // SET
}
else
{
il.Emit(OpCodes.Stfld, (FieldInfo)lastMember); // SET
}
il.Emit(OpCodes.Ret); // GO
setter = (Action <object, DynamicParameters>)dm.CreateDelegate(typeof(Action <object, DynamicParameters>));
lock (cache)
{
cache[lookup] = setter;
}
// Queue the preparation to be fired off when adding parameters to the DbCommand
MAKECALLBACK:
(outputCallbacks is null ? null : new List <Action>()).Add(() =>
{
// Finally, prep the parameter and attach the callback to it
var targetMemberType = lastMemberAccess?.Type;
int sizeToSet = (!size.HasValue && targetMemberType == typeof(string)) ? DbString.DefaultLength : size ?? 0;
if (parameters.TryGetValue(dynamicParamName, out ParamInfo parameter))
{
parameter.ParameterDirection = parameter.AttachedParam.Direction = ParameterDirection.InputOutput;
if (parameter.AttachedParam.Size == 0)
{
parameter.Size = parameter.AttachedParam.Size = sizeToSet;
}
}
else
{
dbType = (!dbType.HasValue)
#pragma warning disable 618
? SqlMapper.LookupDbType(targetMemberType, targetMemberType?.Name, true, out SqlMapper.ITypeHandler handler)
#pragma warning restore 618
: dbType;
// CameFromTemplate property would not apply here because this new param
// Still needs to be added to the command
Add(dynamicParamName, expression.Compile().Invoke(target), null, ParameterDirection.InputOutput, sizeToSet);
}
parameter = parameters[dynamicParamName];
parameter.OutputCallback = setter;
parameter.OutputTarget = target;
});
return(this);
}
/// <summary>
/// Add all the parameters needed to the command just before it executes
/// </summary>
/// <param name="command">The raw command prior to execution</param>
/// <param name="identity">Information about the query</param>
protected void AddParameters(IDbCommand command, SqlMapper.Identity identity)
{
var literals = SqlMapper.GetLiteralTokens(identity.sql);
if (templates != null)
{
foreach (var template in templates)
{
var newIdent = identity.ForDynamicParameters(template.GetType());
Action <IDbCommand, object> appender;
lock (paramReaderCache)
{
if (!paramReaderCache.TryGetValue(newIdent, out appender))
{
appender = SqlMapper.CreateParamInfoGenerator(newIdent, true, RemoveUnused, literals);
paramReaderCache[newIdent] = appender;
}
}
appender(command, template);
}
// The parameters were added to the command, but not the
// DynamicParameters until now.
foreach (IDbDataParameter param in command.Parameters)
{
// If someone makes a DynamicParameters with a template,
// then explicitly adds a parameter of a matching name,
// it will already exist in 'parameters'.
if (!parameters.ContainsKey(param.ParameterName))
{
parameters.Add(param.ParameterName, new ParamInfo
{
AttachedParam = param,
CameFromTemplate = true,
DbType = param.DbType,
Name = param.ParameterName,
ParameterDirection = param.Direction,
Size = param.Size,
Value = param.Value
});
}
}
// Now that the parameters are added to the command, let's place our output callbacks
var tmp = outputCallbacks;
if (tmp != null)
{
foreach (var generator in tmp)
{
generator();
}
}
}
foreach (var param in parameters.Values)
{
if (param.CameFromTemplate)
{
continue;
}
var dbType = param.DbType;
var val = param.Value;
string name = Clean(param.Name);
var isCustomQueryParameter = val is SqlMapper.ICustomQueryParameter;
SqlMapper.ITypeHandler handler = null;
if (dbType == null && val != null && !isCustomQueryParameter)
{
#pragma warning disable 618
dbType = SqlMapper.LookupDbType(val.GetType(), name, true, out handler);
#pragma warning disable 618
}
if (isCustomQueryParameter)
{
((SqlMapper.ICustomQueryParameter)val).AddParameter(command, name);
}
else if (dbType == EnumerableMultiParameter)
{
#pragma warning disable 612, 618
SqlMapper.PackListParameters(command, name, val);
#pragma warning restore 612, 618
}
else
{
bool add = !command.Parameters.Contains(name);
IDbDataParameter p;
if (add)
{
p = command.CreateParameter();
p.ParameterName = name;
}
else
{
p = (IDbDataParameter)command.Parameters[name];
}
p.Direction = param.ParameterDirection;
if (handler == null)
{
#pragma warning disable 0618
p.Value = SqlMapper.SanitizeParameterValue(val);
#pragma warning restore 0618
if (dbType != null && p.DbType != dbType)
{
p.DbType = dbType.Value;
}
var s = val as string;
if (s?.Length <= DbString.DefaultLength)
{
p.Size = DbString.DefaultLength;
}
if (param.Size != null)
{
p.Size = param.Size.Value;
}
if (param.Precision != null)
{
p.Precision = param.Precision.Value;
}
if (param.Scale != null)
{
p.Scale = param.Scale.Value;
}
}
else
{
if (dbType != null)
{
p.DbType = dbType.Value;
}
if (param.Size != null)
{
p.Size = param.Size.Value;
}
if (param.Precision != null)
{
p.Precision = param.Precision.Value;
}
if (param.Scale != null)
{
p.Scale = param.Scale.Value;
}
handler.SetValue(p, val ?? DBNull.Value);
}
if (add)
{
command.Parameters.Add(p);
}
param.AttachedParam = p;
}
}
// note: most non-privileged implementations would use: this.ReplaceLiterals(command);
if (literals.Count != 0)
{
SqlMapper.ReplaceLiterals(this, command, literals);
}
}