Dynamic Linq - String where clause causes parse error

Question

I am trying to convert VB code (VS2010 targeting .Net 4.0) in a data visualization library which uses fluent Linq command syntax (Dim q = From myObj in myTable where ...) into Linq extension method syntax ( Dim q = myTable.where(...)) and am encountering a parsing error in Linq.Dynamic.vb when I attempt to use string expressions without parameter substitution.

Specifically, the following syntax seems to work:

    Dim q = scTbl.Where("CompClass <> @0", "Land")

But the following syntax, although patterned directly from Scott Gu's tutorial, does not:

       Dim q = scTbl.Where("CompClass <> 'Land'")

The run-time exception I get is "DynamicLinq.ParseException was unhandled.  Message=Character literal must contain exactly one character".

Is it not possible to use string where clauses without parameter substitution in Dynamic Linq?

Thanks for any help.

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-BGood

Answer 1

I am not a VB expert (any longer), but it seems that your single quotes are being misinterpreted. Try doubling them up like so:

Dim q = scTbl.Where("CompClass <> ''Land''")

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Answer 2

Thanks Pieter. Good catch.

I changed the syntax to the following:

• Dim q = scTbl.Where("CompClass <> ""Land""")

And Dynamic Linq does not throw the parsing exception.  It looks a little unwieldly with all those quotes, though.

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-BGood