使用带有实体框架的动态字段按子记录排序

Question

I am interested in sorting a query using entity framework and am having trouble sorting using a dynamic order by expression,

I have a parent record (DatasetRecord) with a one to many relationship consisting of a number of associated values (DatasetValues), I would like to be able to sort based on the data stored within the value if it matches a certain field,

So I need to sort by the Value of DatasetValues where it matches a supplied FieldID

public IEnumerable<DatasetRecordDto> FetchData(ModuleSettingsDto settings)
{
    var query = _context.DatasetRecords.AsQueryable().Where(r => r.DatasetId == settings.DatasetId && r.IsDeleted == false);

    foreach (var filter in settings.Filters)
    {
        // this works fine, check we have current field and value matches
        query = query.Where(i => i.DatasetValues.Any(x => x.DatasetFieldId == filter.DatasetFieldId && x.Value == filter.Value));
    }

    foreach (var sort in settings.Sort)
    {
        switch (sort.SortDirection)
        {
            case "asc":
                // THIS IS WHERE I NEED THE DYNAMIC ORDER BY EXPRESSION, 
                // THIS SHOULD SORT BY DATETIME WHERE FIELD ID MATCHES
                query = query.OrderBy(i => i.DatasetValues.Any(x => x.ValueDateTime && x.DatasetFieldId == sort.DatasetFieldId));
                break;
        }

    }

    return ShapeResults(query);
}

And here is my database schema:

CREATE TABLE [dbo].[DatasetRecords](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [DatasetId] [int] NOT NULL
)

CREATE TABLE [dbo].[DatasetFields](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [Label] [varchar](50) NOT NULL,
    [DatasetId] [int] NULL,
    [DataType] [int] NOT NULL
)

CREATE TABLE [dbo].[DatasetValues](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [DatasetRecordId] [int] NOT NULL,
    [DatasetFieldId] [int] NOT NULL,
    [ValueString] [varchar](8000) NULL,
    [ValueInt] [int] NULL,
    [ValueDateTime] [datetime] NULL,
    [ValueDecimal] [decimal](18, 2) NULL,
    [ValueBit] [bit] NULL
)

Please let me know if you need any further info, any help is greatly appreciated,

UPDATE: I am not having an issue with creating a dynamic order by expression, I am trying to apply a conditional sort order for parent records based on the values in a child table

Answer 1

Have you tried running the Linq code on something like LinqPad, it lets you run Linq code against a dataset and shows you the generated SQL. You can take that SQL and run it manually to make sure it isn't some invalid SQL that is causing the error.