Expression BuildExpression(int fieldIndex, ISqlExpression?sqlExpression)
{
Expression expr;
if (SequenceHelper.UnwrapSubqueryContext(Sequence) is DefaultIfEmptyBuilder.DefaultIfEmptyContext defaultIfEmpty)
{
expr = Builder.BuildSql(_returnType, fieldIndex, sqlExpression);
if (defaultIfEmpty.DefaultValue != null && expr is ConvertFromDataReaderExpression convert)
{
var generator = new ExpressionGenerator();
expr = convert.MakeNullable();
if (expr.Type.IsNullable())
{
var exprVar = generator.AssignToVariable(expr, "nullable");
var defaultValue = defaultIfEmpty.DefaultValue;
if (defaultValue.Type != expr.Type)
{
var convertLambda = Builder.MappingSchema.GenerateSafeConvert(defaultValue.Type, expr.Type);
defaultValue = InternalExtensions.ApplyLambdaToExpression(convertLambda, defaultValue);
}
var resultVar = generator.AssignToVariable(defaultValue, "result");
generator.AddExpression(Expression.IfThen(
Expression.NotEqual(exprVar, ExpressionInstances.UntypedNull),
Expression.Assign(resultVar, Expression.Convert(exprVar, resultVar.Type))));
generator.AddExpression(resultVar);
expr = generator.Build();
}
}
}
else
if (_methodName == "Sum" || _returnType.IsNullableType())
{
expr = Builder.BuildSql(_returnType, fieldIndex, sqlExpression);
}
else
{
expr = Expression.Block(
Expression.Call(null, MemberHelper.MethodOf(() => CheckNullValue(false, null !)), Expression.Call(ExpressionBuilder.DataReaderParam, Methods.ADONet.IsDBNull, ExpressionInstances.Constant0), Expression.Constant(_methodName)),
Builder.BuildSql(_returnType, fieldIndex, sqlExpression));
}
return(expr);
}
internal static ParameterAccessor GetParameter(Type type, IDataContext dataContext, SqlField field)
{
var exprParam = Expression.Parameter(typeof(Expression), "expr");
Expression getter = Expression.Convert(
Expression.Property(
Expression.Convert(exprParam, typeof(ConstantExpression)),
ReflectionHelper.Constant.Value),
type);
var descriptor = field.ColumnDescriptor;
var dbValueLambda = descriptor.GetDbParamLambda();
Expression?valueGetter;
Expression?dbDataTypeExpression;
valueGetter = InternalExtensions.ApplyLambdaToExpression(dbValueLambda, getter);
if (typeof(DataParameter).IsSameOrParentOf(valueGetter.Type))
{
dbDataTypeExpression = Expression.Call(Expression.Constant(field.ColumnDescriptor.GetDbDataType(false)),
DbDataType.WithSetValuesMethodInfo,
Expression.PropertyOrField(valueGetter, nameof(DataParameter.DbDataType)));
valueGetter = Expression.PropertyOrField(valueGetter, nameof(DataParameter.Value));
}
else
{
var dbDataType = field.ColumnDescriptor.GetDbDataType(true).WithSystemType(valueGetter.Type);
dbDataTypeExpression = Expression.Constant(dbDataType);
}
var param = ExpressionBuilder.CreateParameterAccessor(
dataContext, valueGetter, getter, dbDataTypeExpression, valueGetter, exprParam, Expression.Parameter(typeof(object[]), "ps"), Expression.Parameter(typeof(IDataContext), "ctx"), field.Name.Replace('.', '_'));
return(param);
}