C# – String.Split in a Linq-To-SQL Query

clinqlinq-to-sqlnet

I have a database table that contains an nvarchar column like this:

1|12.6|18|19

I have a Business Object that has a Decimal[] property.

My LINQ Query looks like this:

var temp = from r in db.SomeTable select new BusinessObject {
    // Other BusinessObject Properties snipped as they are straight 1:1
    MeterValues = r.MeterValues.Split('|').Select(Decimal.Parse).ToArray()
};
var result = temp.ToArray();

This throws an NotSupportedException: Method 'System.String[] Split(Char[])' has no supported translation to SQL.

That kinda sucks 🙂 Is there any way I can do this without having to add a string property to the business object or selecting an anonymous type and then iterating through it?

My current "solution" is:

var temp = from r in db.SomeTable select new {
    mv = r.MeterValues,
    bo = new BusinessObject { // all the other fields }
};
var result = new List<BusinessObject>();
foreach(var t in temp) {
    var bo = t.bo;
    bo.MeterValues = t.mv.Split('|').Select(Decimal.Parse).ToArray();
    result.Add(bo);
}
return result.ToArray(); // The Method returns BusinessObject[]

That's kinda ugly though, with that temporary list.

I've tried adding a let mv = r.MeterValues.Split('|').Select(Decimal.Parse).ToArray() but that essentially leads to the same NotSupportedException.

This is .net 3.5SP1 if that matters.

Best Answer

You need to force the select clause to run on the client by calling .AsEnumerable() first:

var result = db.SomeTable.AsEnumerable().Select(r => new BusinessObject {
    ...
    MeterValues = r.MeterValues.Split('|').Select(Decimal.Parse).ToArray()
}).ToList();
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