Lidarr/Marr.Data/QGen/WhereBuilder.cs

294 lines
11 KiB
C#

using System;
using System.Text;
using System.Linq.Expressions;
using System.Data.Common;
using Marr.Data.Parameters;
using System.Reflection;
using Marr.Data.QGen.Dialects;
namespace Marr.Data.QGen
{
/// <summary>
/// This class utilizes the ExpressionVisitor base class, and it is responsible for creating the "WHERE" clause.
/// It builds a protected StringBuilder class whose output is created when the ToString method is called.
/// It also has some methods that coincide with Linq methods, to provide Linq compatibility.
/// </summary>
/// <typeparam name="T"></typeparam>
public class WhereBuilder<T> : ExpressionVisitor
{
private string _constantWhereClause;
private MapRepository _repos;
private DbCommand _command;
private string _paramPrefix;
private bool _isLeftSide = true;
protected bool _useAltName;
protected Dialect _dialect;
protected StringBuilder _sb;
protected TableCollection _tables;
protected bool _tablePrefix;
public WhereBuilder(string whereClause, bool useAltName)
{
_constantWhereClause = whereClause;
_useAltName = useAltName;
}
public WhereBuilder(DbCommand command, Dialect dialect, Expression filter, TableCollection tables, bool useAltName, bool tablePrefix)
{
_repos = MapRepository.Instance;
_command = command;
_dialect = dialect;
_paramPrefix = command.ParameterPrefix();
_sb = new StringBuilder();
_useAltName = useAltName;
_tables = tables;
_tablePrefix = tablePrefix;
if (filter != null)
{
_sb.AppendFormat("{0} ", PrefixText);
base.Visit(filter);
}
}
protected virtual string PrefixText
{
get
{
return "WHERE";
}
}
protected override Expression VisitBinary(BinaryExpression expression)
{
_sb.Append("(");
_isLeftSide = true;
Visit(expression.Left);
_sb.AppendFormat(" {0} ", Decode(expression));
_isLeftSide = false;
Visit(expression.Right);
_sb.Append(")");
return expression;
}
protected override Expression VisitMethodCall(MethodCallExpression expression)
{
string method = (expression as MethodCallExpression).Method.Name;
switch (method)
{
case "Contains":
Write_Contains(expression);
break;
case "StartsWith":
Write_StartsWith(expression);
break;
case "EndsWith":
Write_EndsWith(expression);
break;
default:
string msg = string.Format("'{0}' expressions are not yet implemented in the where clause expression tree parser.", method);
throw new NotImplementedException(msg);
}
return expression;
}
protected override Expression VisitMemberAccess(MemberExpression expression)
{
if (_isLeftSide)
{
string fqColumn = GetFullyQualifiedColumnName(expression.Member, expression.Expression.Type);
_sb.Append(fqColumn);
}
else
{
// Add parameter to Command.Parameters
string paramName = string.Concat(_paramPrefix, "P", _command.Parameters.Count.ToString());
_sb.Append(paramName);
object value = GetRightValue(expression);
new ParameterChainMethods(_command, paramName, value);
}
return expression;
}
protected override Expression VisitConstant(ConstantExpression expression)
{
if (expression.Value != null)
{
// Add parameter to Command.Parameters
string paramName = string.Concat(_paramPrefix, "P", _command.Parameters.Count.ToString());
_sb.Append(paramName);
var parameter = new ParameterChainMethods(_command, paramName, expression.Value).Parameter;
}
else
{
_sb.Append("NULL");
}
return expression;
}
private object GetRightValue(Expression rightExpression)
{
object rightValue = null;
var right = rightExpression as ConstantExpression;
if (right == null) // Value is not directly passed in as a constant
{
var rightMemberExp = (rightExpression as MemberExpression);
var parentMemberExpression = rightMemberExp.Expression as MemberExpression;
if (parentMemberExpression != null) // Value is passed in as a property on a parent entity
{
string entityName = (rightMemberExp.Expression as MemberExpression).Member.Name;
var container = ((rightMemberExp.Expression as MemberExpression).Expression as ConstantExpression).Value;
var entity = _repos.ReflectionStrategy.GetFieldValue(container, entityName);
rightValue = _repos.ReflectionStrategy.GetFieldValue(entity, rightMemberExp.Member.Name);
}
else // Value is passed in as a variable
{
var parent = (rightMemberExp.Expression as ConstantExpression).Value;
rightValue = _repos.ReflectionStrategy.GetFieldValue(parent, rightMemberExp.Member.Name);
}
}
else // Value is passed in directly as a constant
{
rightValue = right.Value;
}
return rightValue;
}
protected string GetFullyQualifiedColumnName(MemberInfo member, Type declaringType)
{
if (_tablePrefix)
{
Table table = _tables.FindTable(declaringType);
if (table == null)
{
string msg = string.Format("The property '{0} -> {1}' you are trying to reference in the 'WHERE' statement belongs to an entity that has not been joined in your query. To reference this property, you must join the '{0}' entity using the Join method.",
declaringType,
member.Name);
throw new DataMappingException(msg);
}
string columnName = DataHelper.GetColumnName(declaringType, member.Name, _useAltName);
return _dialect.CreateToken(string.Format("{0}.{1}", table.Alias, columnName));
}
else
{
string columnName = DataHelper.GetColumnName(declaringType, member.Name, _useAltName);
return _dialect.CreateToken(columnName);
}
}
private string Decode(BinaryExpression expression)
{
bool isRightSideNullConstant = expression.Right.NodeType ==
ExpressionType.Constant &&
((ConstantExpression)expression.Right).Value == null;
if (isRightSideNullConstant)
{
switch (expression.NodeType)
{
case ExpressionType.Equal: return "IS";
case ExpressionType.NotEqual: return "IS NOT";
}
}
switch (expression.NodeType)
{
case ExpressionType.AndAlso: return "AND";
case ExpressionType.And: return "AND";
case ExpressionType.Equal: return "=";
case ExpressionType.GreaterThan: return ">";
case ExpressionType.GreaterThanOrEqual: return ">=";
case ExpressionType.LessThan: return "<";
case ExpressionType.LessThanOrEqual: return "<=";
case ExpressionType.NotEqual: return "<>";
case ExpressionType.OrElse: return "OR";
case ExpressionType.Or: return "OR";
default: throw new NotSupportedException(string.Format("{0} statement is not supported", expression.NodeType.ToString()));
}
}
private void Write_Contains(MethodCallExpression body)
{
// Add parameter to Command.Parameters
object value = GetRightValue(body.Arguments[0]);
string paramName = string.Concat(_paramPrefix, "P", _command.Parameters.Count.ToString());
var parameter = new ParameterChainMethods(_command, paramName, value).Parameter;
MemberExpression memberExp = (body.Object as MemberExpression);
string fqColumn = GetFullyQualifiedColumnName(memberExp.Member, memberExp.Expression.Type);
_sb.AppendFormat(_dialect.ContainsFormat, fqColumn, paramName);
}
private void Write_StartsWith(MethodCallExpression body)
{
// Add parameter to Command.Parameters
object value = GetRightValue(body.Arguments[0]);
string paramName = string.Concat(_paramPrefix, "P", _command.Parameters.Count.ToString());
var parameter = new ParameterChainMethods(_command, paramName, value).Parameter;
MemberExpression memberExp = (body.Object as MemberExpression);
string fqColumn = GetFullyQualifiedColumnName(memberExp.Member, memberExp.Expression.Type);
_sb.AppendFormat(_dialect.StartsWithFormat, fqColumn, paramName);
}
private void Write_EndsWith(MethodCallExpression body)
{
// Add parameter to Command.Parameters
object value = GetRightValue(body.Arguments[0]);
string paramName = string.Concat(_paramPrefix, "P", _command.Parameters.Count.ToString());
var parameter = new ParameterChainMethods(_command, paramName, value).Parameter;
MemberExpression memberExp = (body.Object as MemberExpression);
string fqColumn = GetFullyQualifiedColumnName(memberExp.Member, memberExp.Expression.Type);
_sb.AppendFormat(_dialect.EndsWithFormat, fqColumn, paramName);
}
/// <summary>
/// Appends the current where clause with another where clause.
/// </summary>
/// <param name="where">The second where clause that is being appended.</param>
/// <param name="appendType">AND / OR</param>
internal void Append(WhereBuilder<T> where, WhereAppendType appendType)
{
_constantWhereClause = string.Format("{0} {1} {2}",
ToString(),
appendType.ToString(),
where.ToString().Replace("WHERE ", string.Empty));
}
public override string ToString()
{
if (string.IsNullOrEmpty(_constantWhereClause))
{
return _sb.ToString();
}
return _constantWhereClause;
}
}
internal enum WhereAppendType
{
AND,
OR
}
}