public SqlScriptBuilder <T> Where(Expression <Func <T, bool> > predict)
{
WherePart wherePart = _whereBuilder.ToSql(predict);
_whereParts.Add(wherePart);
return(this);
}
public static WherePart Concat(string @operator, WherePart operand)
{
return(new WherePart()
{
Parameters = operand.Parameters,
Sql = $"({@operator} {operand.Sql})"
});
}
public static WherePart Concat(WherePart left, string @operator, WherePart right)
{
return(new WherePart()
{
Parameters = left.Parameters.Union(right.Parameters).ToDictionary(kvp => kvp.Key, kvp => kvp.Value),
Sql = $"({left.Sql} {@operator} {right.Sql})"
});
}
private WherePart Recurse(ref int i, Expression expression, bool isUnary = false, string prefix = null, string postfix = null)
{
if (expression is UnaryExpression)
{
var unary = (UnaryExpression)expression;
return(WherePart.Concat(NodeTypeToString(unary.NodeType), Recurse(ref i, unary.Operand, true)));
}
if (expression is BinaryExpression)
{
var body = (BinaryExpression)expression;
return(WherePart.Concat(Recurse(ref i, body.Left), NodeTypeToString(body.NodeType), Recurse(ref i, body.Right)));
}
if (expression is ConstantExpression)
{
var constant = (ConstantExpression)expression;
var value = constant.Value;
if (value is int)
{
return(WherePart.IsSql(value.ToString()));
}
if (value is string)
{
value = prefix + (string)value + postfix;
}
if (value is bool && isUnary)
{
return(WherePart.Concat(WherePart.IsParameter(i++, value), "=", WherePart.IsSql("1")));
}
return(WherePart.IsParameter(i++, value));
}
if (expression is MemberExpression)
{
var member = (MemberExpression)expression;
if (member.Member is PropertyInfo)
{
var property = (PropertyInfo)member.Member;
var colName = property.Name;
if (isUnary && member.Type == typeof(bool))
{
return(WherePart.Concat(Recurse(ref i, expression), "=", WherePart.IsParameter(i++, true)));
}
if (property.PropertyType == typeof(DateTime) && property.ReflectedType == typeof(DateTime))
{
DateTime datetime = (DateTime)property.GetValue(property, null);
string sqlFormattedDate = datetime.Date.ToString("yyyy-MM-dd");
sqlFormattedDate = $"'{sqlFormattedDate}'";
return(WherePart.IsSql(sqlFormattedDate));
}
return(WherePart.IsSql(colName));
}
if (member.Member is FieldInfo)
{
var value = GetValue(member);
if (value is string)
{
value = prefix + (string)value + postfix;
}
return(WherePart.IsParameter(i++, value));
}
throw new Exception($"Expression does not refer to a property or field: {expression}");
}
if (expression is MethodCallExpression)
{
var methodCall = (MethodCallExpression)expression;
// LIKE queries:
if (methodCall.Method == typeof(string).GetMethod("Contains", new[] { typeof(string) }))
{
return(WherePart.Concat(Recurse(ref i, methodCall.Object), "LIKE", Recurse(ref i, methodCall.Arguments[0], prefix: "%", postfix: "%")));
}
if (methodCall.Method == typeof(string).GetMethod("StartsWith", new[] { typeof(string) }))
{
return(WherePart.Concat(Recurse(ref i, methodCall.Object), "LIKE", Recurse(ref i, methodCall.Arguments[0], postfix: "%")));
}
if (methodCall.Method == typeof(string).GetMethod("EndsWith", new[] { typeof(string) }))
{
return(WherePart.Concat(Recurse(ref i, methodCall.Object), "LIKE", Recurse(ref i, methodCall.Arguments[0], prefix: "%")));
}
// IN queries:
if (methodCall.Method.Name == "Contains")
{
Expression collection;
Expression property;
if (methodCall.Method.IsDefined(typeof(ExtensionAttribute)) && methodCall.Arguments.Count == 2)
{
collection = methodCall.Arguments[0];
property = methodCall.Arguments[1];
}
else if (!methodCall.Method.IsDefined(typeof(ExtensionAttribute)) && methodCall.Arguments.Count == 1)
{
collection = methodCall.Object;
property = methodCall.Arguments[0];
}
else
{
throw new Exception("Unsupported method call: " + methodCall.Method.Name);
}
var values = (IEnumerable)GetValue(collection);
return(WherePart.Concat(Recurse(ref i, property), "IN", WherePart.IsCollection(ref i, values)));
}
if (methodCall.Type == typeof(DateTime))
{
//DateTime datetime = (DateTime)property.GetValue(property, null);
//string sqlFormattedDate = datetime.Date.ToString("yyyy-MM-dd");
//sqlFormattedDate = $"'{sqlFormattedDate}'";
//return WherePart.IsSql(sqlFormattedDate);
MethodInfo methodInfo = methodCall.Method;
if (methodInfo != null)
{
object result = null;
ParameterInfo[] parameters = methodInfo.GetParameters();
object classInstance = Activator.CreateInstance(typeof(DateTime), null);
if (parameters.Length == 0)
{
// This works fine
result = methodInfo.Invoke(classInstance, null);
}
else
{
object[] parametersArray = new object[] { 10 };
// The invoke does NOT work;
// it throws "Object does not match target type"
result = methodInfo.Invoke(classInstance, parametersArray);
}
}
string vl = "";
}
throw new Exception("Unsupported method call: " + methodCall.Method.Name);
}
throw new Exception("Unsupported expression: " + expression.GetType().Name);
}
