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c# linq group labmda expression null issue

Posted on 2015-02-16
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Last Modified: 2015-03-03
I have a collection that I am trying to group on.  If this statement does not return a value, I am trying to set the column to 0, but the group returns no results.
 whatIfScenarios.Find(x => x.CbiId == g.First().CbiId && x.Type == WhatIfScenarioType.Plan).WhatIfOutput.RiskMarkScore

here is my code

var group = (from r in riskMarkOutputModel.Recommendations
    where r.InPlan == true
    group r by r.CbiId
    into g
    select
        new
        {
            IndexRecNum = g.First().IndexRecNum,
            a = whatIfScenarios.Find(x => x.CbiId == g.First().CbiId && x.Type == WhatIfScenarioType.Plan).WhatIfOutput.RiskMarkScore ?? 0/*,

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If I leave out the row "a", I get a group.  If I leave "a" in, the group is empty.  Even if the find is blank, I want the group to show.
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Question by:jackjohnson44
2 Comments
 
LVL 11

Accepted Solution

by:
louisfr earned 500 total points
ID: 40630064
If Find returns null, you'd get an exception when trying to retrieve the WhatIfOutput property. Unless you're using C# 6, you need to check that before trying to access the property.
var group = (from r in riskMarkOutputModel.Recommendations
             where r.InPlan == true
             group r by r.CbiId
             into g
             let scenario = whatIfScenarios.Find(x => x.CbiId == g.First().CbiId && x.Type == WhatIfScenarioType.Plan)
             select
                 new
                 {
                     IndexRecNum = g.First().IndexRecNum,
                     a = scenario == null ? 0 : scenario.WhatIfOutput.RiskMarkScore
                 }

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