public override KeyValuePair <string, Expression>?GetExpression <TSource>(Type sourceType, ParameterExpression rootParameter, IEnumerable <TSource> source)
{
// 1. Parse the instruction.
var fieldNames = Parameter.Split(',');
var instructions = fieldNames.Select(s =>
{
return(InstructionHelper.ExtractInstruction(s));
}).Where(s => s.HasValue);
if (instructions.Count() == 0)
{
throw new ArgumentException("the parameter cannot be empty");
}
if (instructions.Any(i => !_orderByInstructions.Contains(i.Value.Key)))
{
throw new ArgumentException("At least one instruction is not supported");
}
var onInstruction = instructions.FirstOrDefault(i => i.Value.Key == _onInstruction);
var orderInstruction = instructions.FirstOrDefault(i => i.Value.Key == _orderInstruction);
if (onInstruction == null)
{
throw new ArgumentException("The 'on' instruction must be specified");
}
var fnName = "OrderBy";
if (orderInstruction != null && orderInstruction.Value.Value == "desc")
{
fnName = "OrderByDescending";
}
// 2. Construct the selector.
ParameterExpression arg = Expression.Parameter(sourceType, "x");
MemberExpression property = Expression.Property(arg, onInstruction.Value.Value);
var selector = Expression.Lambda(property, new ParameterExpression[] { arg });
// 3. Call the order function and return the result.
var enumarableType = typeof(Queryable);
var method = enumarableType.GetMethods()
.Where(m => m.Name == fnName && m.IsGenericMethodDefinition)
.Where(m =>
{
var parameters = m.GetParameters().ToList();
return(parameters.Count == 2);
}).Single().MakeGenericMethod(sourceType, property.Type);
if (SubInstruction != null)
{
var subExpr = SubInstruction.GetExpression(sourceType, rootParameter, source);
var call = Expression.Call(method, subExpr.Value.Value, selector);
return(new KeyValuePair <string, Expression>(Name, call));
}
return(new KeyValuePair <string, Expression>(Name, Expression.Call(method, rootParameter, selector)));
}
public override KeyValuePair <string, Expression>?GetExpression <TSource>(Type outerSourceType, ParameterExpression rootParameter, IEnumerable <TSource> source)
{
if (outerSourceType == null)
{
throw new ArgumentNullException(nameof(outerSourceType));
}
// 1. Split the value & extract the field names or requests.
var splitted = Parameter.Split(',');
var instructions = splitted.Select(s => InstructionHelper.ExtractInstruction(s)).Where(s => s.HasValue);
if (!parameters.Any(p => instructions.Any(i => i.Value.Key == p)))
{
throw new ArgumentException("either inner or outer parameter is not specified");
}
// 2. Construct the expressions.
var outer = instructions.First(i => i.Value.Key == outerKey).Value.Value;
var inner = instructions.First(i => i.Value.Key == innerKey).Value.Value;
var select = instructions.FirstOrDefault(i => i.Value.Key == selectKey);
var selectValue = string.Empty;
if (select != null)
{
selectValue = select.Value.Value;
}
Type innerSourceType = outerSourceType;
Expression targetExpression = null;
if (TargetInstruction != null)
{
var targetArg = Expression.Parameter(typeof(IQueryable <TSource>), "t");
targetExpression = TargetInstruction.GetExpression(outerSourceType, targetArg, source).Value.Value;
innerSourceType = targetExpression.Type.GetGenericArguments().First();
}
Type tResult = innerSourceType;
var fieldNames = outer.GetParameters();
var outerArg = Expression.Parameter(outerSourceType, "x");
var innerArg = Expression.Parameter(innerSourceType, "y");
LambdaExpression outerLambda = null,
innerLambda = null;
Type resultType;
if (fieldNames.Count() == 1)
{
resultType = outerSourceType.GetProperty(fieldNames.First()).PropertyType;
var outerProperty = Expression.Property(outerArg, fieldNames.First());
var innerProperty = Expression.Property(innerArg, fieldNames.First());
outerLambda = Expression.Lambda(outerProperty, new ParameterExpression[] { outerArg });
innerLambda = Expression.Lambda(innerProperty, new ParameterExpression[] { innerArg });
}
else
{
var commonAnonType = ReflectionHelper.CreateNewAnonymousType(outerSourceType, fieldNames);
resultType = commonAnonType.AsType();
var outerNewExpr = ExpressionBuilder.BuildNew(outer, outerSourceType, commonAnonType, outerArg);
var innerNewExpr = ExpressionBuilder.BuildNew(inner, innerSourceType, commonAnonType, innerArg);
outerLambda = Expression.Lambda(outerNewExpr, new ParameterExpression[] { outerArg });
innerLambda = Expression.Lambda(innerNewExpr, new ParameterExpression[] { innerArg });
}
LambdaExpression selectorResult = null;
if (string.IsNullOrWhiteSpace(selectValue))
{
selectorResult = Expression.Lambda(outerArg, new ParameterExpression[] { outerArg, innerArg });
}
else
{
var selectAttributes = new List <KeyValuePair <string, ICollection <string> > >();
foreach (var val in selectValue.Split('|'))
{
var values = val.Split('$');
if (values.Count() != 2 && values.Count() != 1)
{
continue;
}
var key = values.First();
var kvp = selectAttributes.FirstOrDefault(s => s.Key == key);
if (kvp.IsEmpty())
{
kvp = new KeyValuePair <string, ICollection <string> >(key, new List <string>());
selectAttributes.Add(kvp);
}
if (values.Count() == 2)
{
kvp.Value.Add(values.ElementAt(1));
}
}
if (!selectAttributes.Any(a => selectParameters.Contains(a.Key)))
{
throw new InvalidOperationException("At least one parameter in select is not supported");
}
Dictionary <string, Type> mapping = new Dictionary <string, Type>();
var outerSelect = selectAttributes.FirstOrDefault(a => a.Key == outerKey);
var innerSelect = selectAttributes.FirstOrDefault(a => a.Key == innerKey);
AddTypes(mapping, "outer", outerSourceType, outerSelect);
AddTypes(mapping, "inner", innerSourceType, innerSelect);
var anonymousType = ReflectionHelper.CreateNewAnonymousType(mapping);
var parameters = new List <Expression>();
var tmp = GetParameterExpressions(outerArg, outerSelect);
if (tmp != null)
{
parameters.AddRange(tmp);
}
tmp = GetParameterExpressions(innerArg, innerSelect);
if (tmp != null)
{
parameters.AddRange(tmp);
}
var newExpr = Expression.New(anonymousType.DeclaredConstructors.First(), parameters);
selectorResult = Expression.Lambda(newExpr, new ParameterExpression[] { innerArg, outerArg });
tResult = anonymousType.AsType();
}
var enumarableType = typeof(Queryable);
var method = enumarableType.GetMethods().Where(m => m.Name == "Join" && m.IsGenericMethodDefinition).Where(m => m.GetParameters().ToList().Count == 5).First();
var genericMethod = method.MakeGenericMethod(outerSourceType, innerSourceType, resultType, tResult);
MethodCallExpression call = null;
if (targetExpression == null)
{
call = Expression.Call(genericMethod, Expression.Constant(source), Expression.Constant(source), outerLambda, innerLambda, selectorResult);
}
else
{
call = Expression.Call(genericMethod, Expression.Constant(source), targetExpression, Expression.Constant(outerLambda), Expression.Constant(innerLambda), selectorResult);
}
return(new KeyValuePair <string, Expression>(Name, call));
}
public override KeyValuePair <string, Expression>?GetExpression <TSource>(Type sourceType, ParameterExpression rootParameter, IEnumerable <TSource> source)
{
// Callback used to generate the group by expression.
Func <IEnumerable <string>, Type, Type, Expression, MethodCallExpression> getGroupByInst = (names, eType, qType, groupByArg) =>
{
var method = qType.GetMethods()
.Where(m => m.Name == "GroupBy" && m.IsGenericMethodDefinition)
.Where(m => m.GetParameters().ToList().Count == 2).First();
ParameterExpression arg = Expression.Parameter(eType, "x");
MethodInfo genericMethod = null;
LambdaExpression selector = null;
if (names.Count() == 1)
{
var fieldName = names.First();
var propertyInfo = eType.GetProperty(fieldName);
MemberExpression keyProperty = Expression.Property(arg, fieldName);
var keySelector = Expression.Lambda(keyProperty, new ParameterExpression[] { arg });
genericMethod = method.MakeGenericMethod(eType, propertyInfo.PropertyType);
selector = Expression.Lambda(keyProperty, new ParameterExpression[] { arg });
}
else
{
var sourceTypes = names.Select(n => sourceType.GetProperty(n));
var expressions = sourceTypes.Select(s => Expression.Property(arg, s));
var anonType = ReflectionHelper.CreateNewAnonymousType(sourceType, names);
var newExpr = Expression.New(anonType.DeclaredConstructors.First(), expressions);
selector = Expression.Lambda(newExpr, arg);
genericMethod = method.MakeGenericMethod(eType, anonType.AsType());
}
return(Expression.Call(genericMethod, groupByArg, selector));
};
if (sourceType == null)
{
throw new ArgumentNullException(nameof(sourceType));
}
Type queryableType = typeof(Queryable),
enumerableType = typeof(Enumerable);
// 1. Split the value & extract the field names or requests.
var splitted = Parameter.Split(',');
var instructions = splitted.Select(s =>
{
return(InstructionHelper.ExtractInstruction(s));
}).Where(s => s.HasValue);
if (instructions.Count() == 0)
{
return(null);
}
if (instructions.Count() != splitted.Count())
{
throw new ArgumentException("At least one parameter is not an instruction : <operation>(<parameter>)");
}
if (instructions.Any(i => !_groupByInstructions.Contains(i.Value.Key)))
{
throw new ArgumentException("At least one instruction is not supported");
}
var onInstruction = instructions.FirstOrDefault(i => i.Value.Key == _onInstruction);
if (onInstruction == null)
{
throw new ArgumentException("The 'on' instruction must be specified");
}
// r
var sourceQueryableType = typeof(IQueryable <>).MakeGenericType(sourceType);
var sourceEnumerableType = typeof(IEnumerable <>).MakeGenericType(sourceType);
var orderedEnumerableType = typeof(IOrderedEnumerable <>).MakeGenericType(sourceType);
Expression finalSelectArg = null;
if (SubInstruction == null)
{
finalSelectArg = Expression.Constant(source);
}
else
{
finalSelectArg = Expression.Parameter(sourceQueryableType, "r");
}
var fieldNames = onInstruction.Value.Value.Split(_fieldSeparator);
var groupByInst = getGroupByInst(fieldNames, sourceType, queryableType, finalSelectArg);
MethodCallExpression instruction = null;
var aggregateInstruction = instructions.FirstOrDefault(i => i.Value.Key == _aggregateInstruction);
if (aggregateInstruction != null)
{
var aggregateInstructionVal = InstructionHelper.ExtractAggregateInstruction(aggregateInstruction.Value.Value);
if (aggregateInstructionVal == null)
{
throw new ArgumentException("the aggregate instruction is not correct");
}
var kvp = aggregateInstructionVal.Value;
var method = queryableType.GetMethods()
.Where(m => m.Name == "Select" && m.IsGenericMethodDefinition)
.Where(m => m.GetParameters().ToList().Count == 2).First()
.MakeGenericMethod(new Type[] { sourceQueryableType, sourceQueryableType });
var propertyName = kvp.Value;
var propertyInfo = sourceType.GetProperty(propertyName);
// o
var orderArg = Expression.Parameter(sourceType, "o");
// s
var selectArg = Expression.Parameter(sourceEnumerableType, "s");
// b
var selectFirstArg = Expression.Parameter(sourceEnumerableType, "b");
// o => o.[Value]
var keyProperty = Expression.Property(orderArg, propertyName);
var orderBySelector = Expression.Lambda(keyProperty, new ParameterExpression[] { orderArg });
// s => s.OrderBy(o => o.[Value])
MethodCallExpression orderByCall = null;
if (string.Equals(kvp.Key, "max", StringComparison.CurrentCultureIgnoreCase))
{
orderByCall = Expression.Call(enumerableType, "OrderByDescending", new[] { sourceType, propertyInfo.PropertyType }, selectArg, orderBySelector);
}
else
{
orderByCall = Expression.Call(enumerableType, "OrderBy", new[] { sourceType, propertyInfo.PropertyType }, selectArg, orderBySelector);
}
var selectBody = Expression.Lambda(orderByCall, new ParameterExpression[] { selectArg });
var quotedSelectBody = Expression.Quote(selectBody);
// z.GroupBy(x => x.FirstName).Select(s => s.OrderBy(o => o.BirthDate))
var selectRequest = Expression.Call(queryableType, "Select", new[] { sourceEnumerableType, orderedEnumerableType }, groupByInst, quotedSelectBody);
// b => b.First()
var selectFirstRequest = Expression.Call(enumerableType, "First", new[] { sourceType }, selectFirstArg);
var selectFirstLambda = Expression.Lambda(selectFirstRequest, new ParameterExpression[] { selectFirstArg });
instruction = Expression.Call(queryableType, "Select", new[] { sourceEnumerableType, sourceType }, selectRequest, selectFirstLambda);
}
else
{
instruction = groupByInst;
}
return(new KeyValuePair <string, Expression>(Name, instruction));
}
