public static void EvaluateLocals(DynamicLinqCommand command)
{
var locals = command.Locals;
if (locals.Count == 0)
{
command.ParamValues = _emptyArray;
return;
}
// evaluate external parameters - they come from OperationContext
var extValues = _emptyArray;
if (command.ExternalParameters != null && command.ExternalParameters.Length > 0)
{
var ctx = command.Session.Context;
extValues = new object[command.ExternalParameters.Length];
for (int i = 0; i < extValues.Length; i++)
{
extValues[i] = LinqExpressionHelper.EvaluateContextParameterExpression(command.Session, command.ExternalParameters[i]);
} //for i
} //if
// evaluate locals
command.ParamValues = new object[locals.Count];
for (int i = 0; i < locals.Count; i++)
{
var local = locals[i];
command.ParamValues[i] = ExpressionHelper.Evaluate(locals[i], command.ExternalParameters, extValues);
}
} //method
private ValueKind AnalyzeMember(MemberExpression node)
{
// check if it is subquery stored in local variable; if yes, retrieve the value and convert to constant
IQueryable subQuery;
if (LinqExpressionHelper.CheckSubQueryInLocalVariable(node, out subQuery))
{
AnalyzeNode(subQuery.Expression); // we need to visit it as well, to process sub-query nodes
return(ValueKind.Db);
}
if (node.Type.IsSubclassOf(typeof(LinqLiteralBase)))
{
return(ValueKind.Constant);
}
if (node.Type == typeof(SequenceDefinition))
{
return(ValueKind.Constant);
}
//regular member access node
var exprValueKind = this.AnalyzeNode(node.Expression);
AddCacheKey(node.Member.Name);
if (node.Member.IsStaticMember())
{
return(ValueKind.Local);
}
else
{
return(exprValueKind); //same as mexp.Expression's valueKind
}
}
//Detect and retrieve sub-query in local variable
protected override Expression VisitMember(MemberExpression node)
{
IQueryable subQuery;
if (LinqExpressionHelper.CheckSubQueryInLocalVariable(node, out subQuery))
{
var newExpr = Visit(subQuery.Expression);
return(newExpr);
}
return(base.VisitMember(node));
}
private void AnalyzeCommand(DynamicLinqCommand command)
{
_command = command;
_model = command.Session.Context.App.Model;
_cacheKeyBuilder = new SqlCacheKeyBuilder("Linq", command.Kind.ToString(), command.Operation.ToString());
try {
AnalyzeNode(_command.QueryExpression);
//copy some values to command
command.SqlCacheKey = _cacheKeyBuilder.Key;
command.EntityTypes = _entityTypes;
command.LockType = _lockType;
command.Includes = _includes;
command.Options |= _options;
command.Locals.AddRange(_locals);
command.ExternalParameters = _externalParams?.ToArray();
if (command.Locals.Count > 0)
{
LinqExpressionHelper.EvaluateLocals(command);
}
} catch (Exception ex) {
ex.Data["LinqExperssion"] = _command.QueryExpression + string.Empty;
throw;
}
}
