private static WherePart MemberExpressionExtract(ref int i, Expression expression, bool isUnary, string prefix, string postfix, bool left)
{
var member = (MemberExpression)expression;
if (isUnary && member.Type == typeof(bool))
{
return(WherePart.Concat(Recurse(ref i, expression), "=", WherePart.IsSql("1")));
}
if (member.Member is PropertyInfo && left)
{
var property = (PropertyInfo)member.Member;
var colName = GetName <ColumnName>(property);
var tableName = GetName <TableName>(property.DeclaringType.IsAbstract ? ((ParameterExpression)member.Expression).Type : property.DeclaringType);
return(WherePart.IsSql($"[{tableName}].[{ colName }]"));
}
if (member.Member is FieldInfo || left == false)
{
var value = GetValue(member);
if (value is string)
{
value = prefix + (string)value + postfix;
}
return(WherePart.IsParameter(i++, value));
}
throw new Exception($"Expression does not refer to a property or field: {expression}");
}
private static WherePart ConstantExpressionExtract(ref int i, Expression expression, bool isUnary, string prefix, string postfix, bool left)
{
var constant = (ConstantExpression)expression;
var value = constant.Value;
if (value is null)
{
return(WherePart.IsSql("NULL"));
}
if (value is int)
{
return(WherePart.IsSql(value.ToString()));
}
if (value is string)
{
value = prefix + (string)value + postfix;
}
if (value is bool && !isUnary)
{
var result = ((bool)value) ? "1" : "0";
if (left)
{
result = result.Equals("1") ? "1=1" : "0=0";
}
return(WherePart.IsSql(result));
}
return(WherePart.IsParameter(i++, value));
}
private static WherePart ConstantExpressionExtract(ref int i, ConstantExpression expression, bool isUnary,
string prefix, string postfix, bool left)
{
var value = expression.Value;
switch (value)
{
case null:
return(WherePart.IsSql("NULL"));
case int _:
return(WherePart.IsSql(value.ToString()));
case string text:
value = prefix + text + postfix;
break;
}
if (!(value is bool) || isUnary)
{
return(WherePart.IsParameter(i++, value));
}
var result = ((bool)value) ? "1" : "0";
if (left)
{
result = result.Equals("1") ? "1=1" : "0=0";
}
return(WherePart.IsSql(result));
}
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})"
});
}
public static WherePart Concat(string @operator, WherePart operand)
{
return(new WherePart()
{
Parameters = operand.Parameters,
Sql = $"({@operator} {operand.Sql})"
});
}
public static WherePart Concat(WherePart left, string @operator, WherePart right)
{
if (right.Sql.Equals("NULL", StringComparison.InvariantCultureIgnoreCase))
{
@operator = @operator == "=" ? "IS" : "IS NOT";
}
return(new WherePart($"({left.Sql} {@operator} {right.Sql})", left.Parameters.Union(right.Parameters)));
}
private static WherePart MethodCallExpressionExtract <T>(ref int i, MethodCallExpression expression)
{
// LIKE queries:
if (expression.Method == typeof(string).GetMethod("Contains", new[] { typeof(string) }))
{
return(WherePart.Concat(Recurse <T>(ref i, expression.Object), "LIKE",
Recurse <T>(ref i, expression.Arguments[0], prefix: "%", postfix: "%")));
}
if (expression.Method == typeof(string).GetMethod("StartsWith", new[] { typeof(string) }))
{
return(WherePart.Concat(Recurse <T>(ref i, expression.Object), "LIKE",
Recurse <T>(ref i, expression.Arguments[0], postfix: "%")));
}
if (expression.Method == typeof(string).GetMethod("EndsWith", new[] { typeof(string) }))
{
return(WherePart.Concat(Recurse <T>(ref i, expression.Object), "LIKE",
Recurse <T>(ref i, expression.Arguments[0], prefix: "%")));
}
if (expression.Method == typeof(string).GetMethod("Equals", new[] { typeof(string) }))
{
return(WherePart.Concat(Recurse <T>(ref i, expression.Object), "=",
Recurse <T>(ref i, expression.Arguments[0], left: false)));
}
// IN queries:
if (expression.Method.Name == "Contains")
{
Expression collection;
Expression property;
if (expression.Method.IsDefined(typeof(ExtensionAttribute)) && expression.Arguments.Count == 2)
{
collection = expression.Arguments[0];
property = expression.Arguments[1];
}
else if (!expression.Method.IsDefined(typeof(ExtensionAttribute)) && expression.Arguments.Count == 1)
{
collection = expression.Object;
property = expression.Arguments[0];
}
else
{
throw new Exception("Unsupported method call: " + expression.Method.Name);
}
var values = (IEnumerable)GetValue(collection);
return(WherePart.Concat(Recurse <T>(ref i, property), "IN", WherePart.IsCollection(ref i, values)));
}
throw new Exception("Unsupported method call: " + expression.Method.Name);
}
public static WherePart Concat(WherePart left, string @operator, WherePart right)
{
if (right.Sql.Equals("NULL", StringComparison.InvariantCultureIgnoreCase))
{
@operator = @operator == "=" ? "IS" : "IS NOT";
}
return(new WherePart()
{
Parameters = left.Parameters.Union(right.Parameters).ToDictionary(kvp => kvp.Key, kvp => kvp.Value),
Sql = $"({left.Sql} {@operator} {right.Sql})"
});
}
private static WherePart ConstantExpressionExtract(ref int i, Expression expression, bool isUnary, string prefix, string postfix)
{
var constant = (ConstantExpression)expression;
var value = constant.Value;
if (value is int)
{
return(WherePart.IsSql(value.ToString()));
}
if (value is string)
{
value = prefix + (string)value + postfix;
}
if (value is bool && isUnary)
{
return(WherePart.Concat(WherePart.IsParameter(i++, value), "=", WherePart.IsSql("1")));
}
return(WherePart.IsParameter(i++, value));
}
private static WherePart UnaryExpressionExtract(ref int i, Expression expression)
{
var unary = (UnaryExpression)expression;
return(WherePart.Concat(NodeTypeToString(unary.NodeType), Recurse(ref i, unary.Operand, true)));
}
private static WherePart BinaryExpressionExtract(ref int i, Expression expression)
{
var body = (BinaryExpression)expression;
return(WherePart.Concat(Recurse(ref i, body.Left, left: true), NodeTypeToString(body.NodeType), Recurse(ref i, body.Right, left: false)));
}
public static WherePart Concat(string @operator, WherePart operand)
{
return(new WherePart($"({@operator} {operand.Sql})", operand.Parameters));
}
private static WherePart UnaryExpressionExtract <T>(ref int i, UnaryExpression expression)
{
return(WherePart.Concat(NodeTypeToString(expression.NodeType), Recurse <T>(ref i, expression.Operand, true)));
}
private static WherePart BinaryExpressionExtract <T>(ref int i, BinaryExpression expression)
{
return(WherePart.Concat(Recurse <T>(ref i, expression.Left), NodeTypeToString(expression.NodeType),
Recurse <T>(ref i, expression.Right, left: false)));
}
