private static Expression GetExpression <T>(ParameterExpression param, ExpressionInput filter)
{
try
{
MemberExpression member = Expression.Property(param, filter.PropertyName);
ConstantExpression constant = Expression.Constant(filter.Value);
ConstantExpression stringComparisonConstant = Expression.Constant(StringComparison.OrdinalIgnoreCase);
switch (filter.Operation)
{
case Operation.Equals:
return(Expression.Equal(member, constant));
case Operation.NotEquals:
return(Expression.NotEqual(member, constant));
case Operation.GreaterThan:
return(Expression.GreaterThan(member, constant));
case Operation.GreaterThanOrEqual:
return(Expression.GreaterThanOrEqual(member, constant));
case Operation.LessThan:
return(Expression.LessThan(member, constant));
case Operation.LessThanOrEqual:
return(Expression.LessThanOrEqual(member, constant));
case Operation.Contains:
return(Expression.Call(member, containsMethod, new[] { constant }));
case Operation.ContainsWithToLower:
var toLowerMember = Expression.Call(member, toLowerMethod);
return(Expression.Call(toLowerMember, containsMethod, constant));
case Operation.ToStringWithContains:
var tostringMember = Expression.Call(member, toStringMethod);
return(Expression.Call(tostringMember, containsMethod, constant));
case Operation.StartsWith:
return(Expression.Call(member, startsWithMethod, constant));
case Operation.EndsWith:
return(Expression.Call(member, endsWithMethod, constant));
case Operation.StringEquals:
var zeroConstant = Expression.Constant(0);
var compareExpression = Expression.Call(compareMethod, member, constant, stringComparisonConstant);
return(Expression.Equal(compareExpression, zeroConstant));
}
return(null);
}
catch (Exception e)
{
throw new Exception(e.Message);
}
}
public ExpressionInput getExpressionInput(string expressionStr)
{
//switch(contain(expressionStr,"=="))
//{
// case true:
// return
//}
ExpressionInput expressionInput = new ExpressionInput();
if (expressionStr.Contains("=="))
{
string result = expressionStr;
int start = result.LastIndexOf('=') + 1;
int length = result.Length;
expressionInput.PropertyName = result.Substring(0, result.IndexOf('=')).Trim();
expressionInput.Value = result.Substring(start, (length - start)).Trim().Trim(')').Trim('\"');
expressionInput.Operation = Operation.Equals;
}
else if (expressionStr.Contains("<="))
{
string result = expressionStr;
int start = result.LastIndexOf('=') + 1;
int length = result.Length;
expressionInput.PropertyName = result.Substring(0, result.IndexOf('<')).Trim();
expressionInput.Value = result.Substring(start, (length - start)).Trim().Trim(')').Trim('\"');
expressionInput.Operation = Operation.LessThanOrEqual;
}
else if (expressionStr.Contains(">="))
{
string result = expressionStr;
int start = result.LastIndexOf('=') + 1;
int length = result.Length;
expressionInput.PropertyName = result.Substring(0, result.IndexOf('>')).Trim();
expressionInput.Value = result.Substring(start, (length - start)).Trim().Trim(')').Trim('\"');
expressionInput.Operation = Operation.GreaterThanOrEqual;
}
else if (expressionStr.Contains("<"))
{
string result = expressionStr;
int start = result.LastIndexOf('<') + 1;
int length = result.Length;
expressionInput.PropertyName = result.Substring(0, result.IndexOf('<')).Trim();
expressionInput.Value = result.Substring(start, (length - start)).Trim().Trim(')').Trim('\"');
expressionInput.Operation = Operation.LessThan;
}
else if (expressionStr.Contains(">"))
{
string result = expressionStr;
int start = result.LastIndexOf('>') + 1;
int length = result.Length;
expressionInput.PropertyName = result.Substring(0, result.IndexOf('>')).Trim();
expressionInput.Value = result.Substring(start, (length - start)).Trim().Trim(')').Trim('\"');
expressionInput.Operation = Operation.GreaterThan;
}
else if (expressionStr.Contains("!="))
{
string result = expressionStr;
int start = result.LastIndexOf('=') + 1;
int length = result.Length;
expressionInput.PropertyName = result.Substring(0, result.IndexOf('!')).Trim();
expressionInput.Value = result.Substring(start, (length - start)).Trim().Trim(')').Trim('\"');
expressionInput.Operation = Operation.NotEquals;
}
return(expressionInput);
}
