/// <summary>
/// Translate a NewInstance(Element(X)) expression into
/// "select top(1) * from X"
/// </summary>
/// <param name="e"></param>
/// <returns></returns>
private ISqlFragment VisitCollectionConstructor(DbNewInstanceExpression e)
{
Debug.Assert(e.Arguments.Count <= 1);
if (e.Arguments.Count == 1 && e.Arguments[0].ExpressionKind == DbExpressionKind.Element)
{
DbElementExpression elementExpr = e.Arguments[0] as DbElementExpression;
SqlSelectStatement result = VisitExpressionEnsureSqlStatement(elementExpr.Argument);
if (!IsCompatible(result, DbExpressionKind.Element))
{
Symbol fromSymbol;
TypeUsage inputType = MetadataHelpers.GetElementTypeUsage(elementExpr.Argument.ResultType);
result = CreateNewSelectStatement(result, "element", inputType, out fromSymbol);
AddFromSymbol(result, "element", fromSymbol, false);
}
result.Top.SetTopCount(1);
return(result);
}
// Otherwise simply build this out as a union-all ladder
CollectionType collectionType = MetadataHelpers.GetEdmType <CollectionType>(e.ResultType);
Debug.Assert(collectionType != null);
bool isScalarElement = MetadataHelpers.IsPrimitiveType(collectionType.TypeUsage);
SqlBuilder resultSql = new SqlBuilder();
string separator = "";
// handle empty table
if (e.Arguments.Count == 0)
{
Debug.Assert(isScalarElement);
resultSql.Append(" select cast(null as ");
resultSql.Append(MetadataHelpers.GetSqlPrimitiveType(collectionType.TypeUsage));
resultSql.Append(") as x from (select 1) as y where 1=0");
}
foreach (DbExpression arg in e.Arguments)
{
resultSql.Append(separator);
resultSql.Append(" select ");
resultSql.Append(arg.Accept(this));
// For scalar elements, no alias is appended yet. Add this.
if (isScalarElement)
{
resultSql.Append(" as x ");
}
separator = " union all ";
}
return(resultSql);
}
/// <summary>
/// This is called from <see cref="GenerateSql(DbQueryCommandTree)"/> and nodes which require a
/// select statement as an argument e.g. <see cref="Visit(DbIsEmptyExpression)"/>,
/// <see cref="Visit(DbUnionAllExpression)"/>.
///
/// SqlGenerator needs its child to have a proper alias if the child is
/// just an extent or a join.
///
/// The normal relational nodes result in complete valid SQL statements.
/// For the rest, we need to treat them as there was a dummy
/// <code>
/// -- originally {expression}
/// -- change that to
/// SELECT *
/// FROM {expression} as c
/// </code>
///
/// DbLimitExpression needs to start the statement but not add the default columns
/// </summary>
/// <param name="e"></param>
/// <param name="addDefaultColumns"></param>
/// <returns></returns>
private SqlSelectStatement VisitExpressionEnsureSqlStatement(DbExpression e, bool addDefaultColumns)
{
Debug.Assert(MetadataHelpers.IsCollectionType(e.ResultType.EdmType));
SqlSelectStatement result;
switch (e.ExpressionKind)
{
case DbExpressionKind.Project:
case DbExpressionKind.Filter:
case DbExpressionKind.GroupBy:
case DbExpressionKind.Sort:
result = e.Accept(this) as SqlSelectStatement;
break;
default:
string inputVarName = "c"; // any name will do - this is my random choice.
symbolTable.EnterScope();
TypeUsage type = null;
switch (e.ExpressionKind)
{
case DbExpressionKind.Scan:
case DbExpressionKind.CrossJoin:
case DbExpressionKind.FullOuterJoin:
case DbExpressionKind.InnerJoin:
case DbExpressionKind.LeftOuterJoin:
case DbExpressionKind.CrossApply:
case DbExpressionKind.OuterApply:
// It used to be type = e.ResultType.
type = MetadataHelpers.GetElementTypeUsage(e.ResultType);
break;
default:
Debug.Assert(MetadataHelpers.IsCollectionType(e.ResultType.EdmType));
type = MetadataHelpers.GetEdmType <CollectionType>(e.ResultType).TypeUsage;
break;
}
Symbol fromSymbol;
result = VisitInputExpression(e, inputVarName, type, out fromSymbol);
AddFromSymbol(result, inputVarName, fromSymbol);
symbolTable.ExitScope();
break;
}
if (addDefaultColumns && result.Select.IsEmpty)
{
AddDefaultColumns(result);
}
return(result);
}
private static Type[] PrepareTypeCoercions(DbCommandTree commandTree)
{
var queryTree = commandTree as DbQueryCommandTree;
if (queryTree != null)
{
var projectExpression = queryTree.Query as DbProjectExpression;
if (projectExpression != null)
{
var resultsType = projectExpression.Projection.ResultType.EdmType;
var resultsAsStructuralType = resultsType as StructuralType;
if (resultsAsStructuralType != null)
{
var result = new Type[resultsAsStructuralType.Members.Count];
for (int i = 0; i < resultsAsStructuralType.Members.Count; i++)
{
var member = resultsAsStructuralType.Members[i];
result[i] = ((PrimitiveType)member.TypeUsage.EdmType).ClrEquivalentType;
}
return(result);
}
}
}
var functionTree = commandTree as DbFunctionCommandTree;
if (functionTree != null)
{
if (functionTree.ResultType != null)
{
var elementType = MetadataHelpers.GetElementTypeUsage(functionTree.ResultType).EdmType;
if (MetadataHelpers.IsRowType(elementType))
{
var members = ((RowType)elementType).Members;
var result = new Type[members.Count];
for (int i = 0; i < members.Count; i++)
{
var member = members[i];
var primitiveType = (PrimitiveType)member.TypeUsage.EdmType;
result[i] = primitiveType.ClrEquivalentType;
}
return(result);
}
else if (MetadataHelpers.IsPrimitiveType(elementType))
{
return(new Type[] { ((PrimitiveType)elementType).ClrEquivalentType });
}
}
}
return(null);
}
public override ISqlFragment Visit(DbDistinctExpression e)
{
var result = VisitExpressionEnsureSqlStatement(e.Argument);
if (!IsCompatible(result, e.ExpressionKind))
{
Symbol fromSymbol;
TypeUsage inputType = MetadataHelpers.GetElementTypeUsage(e.Argument.ResultType);
result = CreateNewSelectStatement(result, "distinct", inputType, out fromSymbol);
AddFromSymbol(result, "distinct", fromSymbol, false);
}
result.IsDistinct = true;
return(result);
}
private static Type[] PrepareTypeCoercions(DbCommandTree commandTree)
{
var queryTree = commandTree as DbQueryCommandTree;
if (queryTree != null)
{
var projectExpression = queryTree.Query as DbProjectExpression;
if (projectExpression != null)
{
var resultsType = projectExpression.Projection.ResultType.EdmType;
var resultsAsStructuralType = resultsType as StructuralType;
if (resultsAsStructuralType != null)
{
var members = resultsAsStructuralType.Members;
return(members.Select(ExtractExpectedTypeForCoercion).ToArray());
}
}
}
var functionTree = commandTree as DbFunctionCommandTree;
if (functionTree != null)
{
if (functionTree.ResultType != null)
{
Debug.Assert(MetadataHelpers.IsCollectionType(functionTree.ResultType.EdmType), "Result type of a function is expected to be a collection of RowType or PrimitiveType");
var typeUsage = MetadataHelpers.GetElementTypeUsage(functionTree.ResultType);
var elementType = typeUsage.EdmType;
if (MetadataHelpers.IsRowType(elementType))
{
var members = ((RowType)elementType).Members;
return(members.Select(ExtractExpectedTypeForCoercion).ToArray());
}
else if (MetadataHelpers.IsPrimitiveType(elementType))
{
return(new[] { MakeTypeCoercion(((PrimitiveType)elementType).ClrEquivalentType, typeUsage) });
}
else
{
Debug.Fail("Result type of a function is expected to be a collection of RowType or PrimitiveType");
}
}
}
return(null);
}
/// <summary>
/// Translates to TOP expression.
/// </summary>
/// <param name="e"></param>
/// <returns>A <see cref="SqlBuilder"/></returns>
public override ISqlFragment Visit(DbLimitExpression e)
{
Debug.Assert(e.Limit is DbConstantExpression || e.Limit is DbParameterReferenceExpression, "DbLimitExpression.Limit is of invalid expression type");
var result = VisitExpressionEnsureSqlStatement(e.Argument, false);
if (!IsCompatible(result, e.ExpressionKind))
{
TypeUsage inputType = MetadataHelpers.GetElementTypeUsage(e.Argument.ResultType);
Symbol fromSymbol;
result = CreateNewSelectStatement(result, "first", inputType, out fromSymbol);
AddFromSymbol(result, "first", fromSymbol, false);
}
result.Top.TopCount = HandleCountExpression(e.Limit);
return(result);
}
/// <summary>
/// Create a SampleCommand object, given the provider manifest and command tree
/// </summary>
private DbCommand CreateCommand(DbProviderManifest manifest, DbCommandTree commandTree)
{
if (manifest == null)
{
throw new ArgumentNullException("manifest");
}
if (commandTree == null)
{
throw new ArgumentNullException("commandTree");
}
FbCommand command = new FbCommand();
#region Type coercions
// Set expected column types for DbQueryCommandTree
DbQueryCommandTree queryTree = commandTree as DbQueryCommandTree;
if (queryTree != null)
{
DbProjectExpression projectExpression = queryTree.Query as DbProjectExpression;
if (projectExpression != null)
{
EdmType resultsType = projectExpression.Projection.ResultType.EdmType;
StructuralType resultsAsStructuralType = resultsType as StructuralType;
if (resultsAsStructuralType != null)
{
command.ExpectedColumnTypes = new PrimitiveType[resultsAsStructuralType.Members.Count];
for (int ordinal = 0; ordinal < resultsAsStructuralType.Members.Count; ordinal++)
{
EdmMember member = resultsAsStructuralType.Members[ordinal];
PrimitiveType primitiveType = member.TypeUsage.EdmType as PrimitiveType;
command.ExpectedColumnTypes[ordinal] = primitiveType;
}
}
}
}
// Set expected column types for DbFunctionCommandTree
DbFunctionCommandTree functionTree = commandTree as DbFunctionCommandTree;
if (functionTree != null)
{
if (functionTree.ResultType != null)
{
Debug.Assert(MetadataHelpers.IsCollectionType(functionTree.ResultType.EdmType), "Result type of a function is expected to be a collection of RowType or PrimitiveType");
EdmType elementType = MetadataHelpers.GetElementTypeUsage(functionTree.ResultType).EdmType;
if (MetadataHelpers.IsRowType(elementType))
{
ReadOnlyMetadataCollection <EdmMember> members = ((RowType)elementType).Members;
command.ExpectedColumnTypes = new PrimitiveType[members.Count];
for (int ordinal = 0; ordinal < members.Count; ordinal++)
{
EdmMember member = members[ordinal];
PrimitiveType primitiveType = (PrimitiveType)member.TypeUsage.EdmType;
command.ExpectedColumnTypes[ordinal] = primitiveType;
}
}
else if (MetadataHelpers.IsPrimitiveType(elementType))
{
command.ExpectedColumnTypes = new PrimitiveType[1];
command.ExpectedColumnTypes[0] = (PrimitiveType)elementType;
}
else
{
Debug.Fail("Result type of a function is expected to be a collection of RowType or PrimitiveType");
}
}
}
#endregion
List <DbParameter> parameters;
CommandType commandType;
command.CommandText = SqlGenerator.GenerateSql(commandTree, out parameters, out commandType);
command.CommandType = commandType;
// Get the function (if any) implemented by the command tree since this influences our interpretation of parameters
EdmFunction function = null;
if (commandTree is DbFunctionCommandTree)
{
function = ((DbFunctionCommandTree)commandTree).EdmFunction;
}
// Now make sure we populate the command's parameters from the CQT's parameters:
foreach (KeyValuePair <string, TypeUsage> queryParameter in commandTree.Parameters)
{
FbParameter parameter;
// Use the corresponding function parameter TypeUsage where available (currently, the SSDL facets and
// type trump user-defined facets and type in the EntityCommand).
FunctionParameter functionParameter;
if (null != function && function.Parameters.TryGetValue(queryParameter.Key, false, out functionParameter))
{
parameter = CreateSqlParameter(functionParameter.Name, functionParameter.TypeUsage, functionParameter.Mode, DBNull.Value);
}
else
{
parameter = CreateSqlParameter(queryParameter.Key, queryParameter.Value, ParameterMode.In, DBNull.Value);
}
command.Parameters.Add(parameter);
}
// Now add parameters added as part of SQL gen (note: this feature is only safe for DML SQL gen which
// does not support user parameters, where there is no risk of name collision)
if (null != parameters && 0 < parameters.Count)
{
if (!(commandTree is DbInsertCommandTree) &&
!(commandTree is DbUpdateCommandTree) &&
!(commandTree is DbDeleteCommandTree))
{
throw new InvalidOperationException("SqlGenParametersNotPermitted");
}
foreach (DbParameter parameter in parameters)
{
command.Parameters.Add(parameter);
}
}
return(command);
}
