Gemli.Data: Basic LINQ Support

by Jon Davis 6. June 2010 04:13

In the Development branch of Gemli.Data, I finally got around to adding some very, very basic LINQ support. The following test scenarios currently seem to function correctly:

var myCustomEntityQuery = new DataModelQuery<DataModel<MockObject>>();
// Scenarios 1-3: Where() lambda, boolean operator, method exec
var linqq = myCustomEntityQuery.Where(mo => mo.Entity.MockStringValue == "dah");
linqq = myCustomEntityQuery.Where(mo => mo.Entity.MockStringValue != "dah");
// In the following scenario, GetPropertyValueByColumnName() is an explicitly supported method
linqq = myCustomEntityQuery.Where(mo=>((int)mo.GetPropertyValueByColumnName("customentity_id")) > -1);
// Scenario 4: LINQ formatted query
var q = (from mo in myCustomEntityQuery
where mo.Entity.MockStringValue != "st00pid"
select mo) as DataModelQuery<DataModel<MockObject>>;
// Scenario 5: LINQ formatted query execution with sorted ordering
var orderedlist = (from mo in myCustomEntityQuery
where mo.Entity.MockStringValue != "def"
orderby mo.Entity.MockStringValue
select mo).ToList();
// Scenario 6: LINQ formatted query with multiple conditions and multiple sort members
var orderedlist = (from mo in myCustomEntityQuery
where mo.Entity.MockStringValue != "def" && mo.Entity.ID < 3
orderby mo.Entity.ID, mo.Entity.MockStringValue
select mo).ToList();

This is a great milestone, one I’m very pleased with myself for finally accomplishing. There’s still a ton more to do but these were the top 50% or so of LINQ support scenarios needed in Gemli.Data.

Unfortunately, adding LINQ support brought about a rather painful rediscovery of critical missing functionality: the absence of support for OR (||) and condition groups in Gemli.Data queries. *facepalm*  I left it out earlier as a to-do item but completely forgot to come back to it. That’s next on my plate. *burp*


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About the author

Jon Davis (aka "stimpy77") has been a programmer, developer, and consultant for web and Windows software solutions professionally since 1997, with experience ranging from OS and hardware support to DHTML programming to IIS/ASP web apps to Java network programming to Visual Basic applications to C# desktop apps.
Software in all forms is also his sole hobby, whether playing PC games or tinkering with programming them. "I was playing Defender on the Commodore 64," he reminisces, "when I decided at the age of 12 or so that I want to be a computer programmer when I grow up."

Jon was previously employed as a senior .NET developer at a very well-known Internet services company whom you're more likely than not to have directly done business with. However, this blog and all of have no affiliation with, and are not representative of, his former employer in any way.

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