protected override Expression VisitMethodCall(MethodCallExpression node)
{
var name = node.Method.Name;
LambdaExpression lambdaExpression;
switch (name)
{
case "Where":
lambdaExpression = GetLambdaExpression(node);
var whereTranslator = new WhereQueryTranslator();
WhereClause = whereTranslator.Translate(lambdaExpression);
Visit(node.Arguments[0]);
break;
case "FirstOrDefault":
FirstOrDefaultClause = "TOP 1 *";
Visit(node.Arguments[0]);
break;
case "ThenBy":
case "OrderBy":
case "OrderByDescending":
case "ThenByDescending":
var sortingType = name.Contains("Descending") ? SortingType.DESC : SortingType.ASC;
lambdaExpression = GetLambdaExpression(node);
var orderByTranslator = new OrderByQueryTranslator(sortingType);
orderByClauses_.Add(orderByTranslator.Translate(lambdaExpression));
Visit(node.Arguments[0]);
break;
case "Select":
lambdaExpression = GetLambdaExpression(node);
var selectTranslator = new SelectQueryTranslator();
SelectClause = selectTranslator.Translate(lambdaExpression);
Visit(node.Arguments[0]);
break;
default:
break;
}
return(node);
}
private void VisitOrderByStatements(List <MethodCallExpression> callChain, Type typeResult)
{
string[] names = new[] { nameof(q.OrderBy), nameof(q.ThenBy), nameof(q.OrderByDescending), nameof(q.ThenByDescending) };
List <MethodCallExpression> tmp = callChain.Where(p => names.Contains(p.Method.Name)).ToList();
OrderByQueryTranslator s = new OrderByQueryTranslator(typeResult);
foreach (MethodCallExpression item in tmp)
{
s.Accept(item);
callChain.Remove(item);
}
if (!string.IsNullOrEmpty(s.Statement))
{
OrderByPart = $" ORDER BY {s.Statement}";
}
}
public override string TranslateToSql(Expression expr)
{
var externalPredicates = new List <Expression <Func <ShadowRow, bool> > >();
var itIsCount = false;
var itIsFirst = false;
var skipUsed = ExpressionsInternalToolkit.SkipIsUsed(expr);
var takeUsed = ExpressionsInternalToolkit.TakeIsUsed(expr);
#pragma warning disable CS0642
if (itIsCount = ExpressionsInternalToolkit.IsCountQueryableCall(expr))
{
;
}
else if (itIsFirst = ExpressionsInternalToolkit.IsFirstQueryableCall(expr) ||
ExpressionsInternalToolkit.IsFirstOrDefaultQueryableCall(expr))
{
;
}
#pragma warning restore CS0642
var selectOnlyTranslator = new SelectOnlyTranslator();
if (itIsCount)
{
_sb.Append("SELECT COUNT (");
_sb.Append(selectOnlyTranslator.TranslateToSql(expr));
_sb.Append(") FROM ");
var mCall = expr as MethodCallExpression;
if (mCall.Arguments.Count == 2)
{
var lambda = ExpressionsInternalToolkit.SkipUnary(mCall.Arguments[1]) as LambdaExpression; // skip Quote
var lambdaTyped =
Expression.Lambda <Func <ShadowRow, bool> >(lambda.Body, ExpressionBuilders.DefaultRowParameter);
externalPredicates.Add(lambdaTyped);
}
}
else if (itIsFirst && !skipUsed)
{
_sb.Append("SELECT TOP 1 ");
_sb.Append(selectOnlyTranslator.TranslateToSql(expr));
_sb.Append(" FROM ");
var mCall = expr as MethodCallExpression;
if (mCall.Arguments.Count == 2)
{
var lambda = ExpressionsInternalToolkit.SkipUnary(mCall.Arguments[1]) as LambdaExpression; // skip Quote
var lambdaTyped =
Expression.Lambda <Func <ShadowRow, bool> >(lambda.Body, ExpressionBuilders.DefaultRowParameter);
externalPredicates.Add(lambdaTyped);
}
}
else
{
_sb.Append("SELECT ");
_sb.Append(selectOnlyTranslator.TranslateToSql(expr));
_sb.Append(" FROM ");
}
_sb.Append(_sourceName);
var whereLine = new WhereQueryTranslator(_queryParamsStore,
externalPredicates.Any() ? externalPredicates.ToArray() : null)
.TranslateToSql(expr);
if (!string.IsNullOrWhiteSpace(whereLine))
{
_sb.Append(" WHERE ");
_sb.Append(whereLine);
}
if (!itIsCount)
{
var orderByLine = new OrderByQueryTranslator(_queryParamsStore)
.TranslateToSql(expr);
var orderByUsed = !string.IsNullOrWhiteSpace(orderByLine);
if (orderByUsed)
{
_sb.Append(" ORDER BY ");
_sb.Append(orderByLine);
}
if (skipUsed)
{
if (!orderByUsed)
{
_sb.Append(" ORDER BY (SELECT NULL)");
}
_sb.Append(" OFFSET ");
var skipCount = ExpressionsInternalToolkit.GetSkipCount(expr);
_sb.Append(_queryParamsStore.Append(skipCount));
_sb.Append(" ROWS");
}
if (takeUsed)
{
if (!skipUsed)
{
if (!orderByUsed)
{
_sb.Append(" ORDER BY (SELECT NULL)");
}
_sb.Append(" OFFSET 0 ROWS");
}
_sb.Append(" FETCH NEXT ");
var takeCount = ExpressionsInternalToolkit.GetTakeCount(expr);
_sb.Append(_queryParamsStore.Append(takeCount));
_sb.Append(" ROW ONLY");
}
}
if (itIsFirst && skipUsed)
{
_sb.Append(" FETCH NEXT 1 ROW ONLY");
}
return(_sb.ToString());
}
