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Checking to see if A field has a null value

DavidAshton

I have created a graphic layer by a attribute/spatial selection tools. I've created a graphic layer named graphicLayer. I want to check to see if a field (AsBuiltDate) is null but I'm having trouble with the code/syntax. Can someone help?

if (graphicsLayer.Graphics.Attributes["AsBuiltDate"] == "NULL")                 {                 }

Thanks
Dave

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Accepted answers

JenniferNery

You can use query.Where = "NOT (description is NULL)".

http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Fire/Sheep/FeatureServer/0/query?objectIds=&where=not+%28description+is+NULL%29&time=&geometry=&geometryType=esriGeometryEnvelope&inSR=&spatialRel=esriSpatialRelIntersects&relationParam=&outFields=*&returnGeometry=true&outSR=&returnIdsOnly=false&f=html

Or if you have already retrieved all features and want to filter the results via client API, you can use linq Query, you can do the following in QueryTask.ExecuteCompleted event handler:

var nonNullValues = from f in e.FeatureSet.Features  where f.Attributes["description"] != null  select f;

All comments

JenniferNery

var nonNullValues = from f in e.FeatureSet.Features  where f.Attributes["description"] != null  select f;

DavidAshton

Thanks Jay...that got me halfway there. The rest wanted something like "AsBuilt_Date is NULL" but is was erroring with the null so I did something like graphics1.Attributes["AsBuilt_Date"] is Nullable

my code doesn't crash but it is not working entirely. I'm trying loop there several graphics and only a few records are null here's what I'm trying to do:

 if (PieChartLayers.SelectedIndex == 3)
                {
                      //      PieChart.Title = "ASBUILT DATE"; AsBuiltDate

                    foreach (Graphic graphics1 in graphicsLayer.Graphics)
                    {

                        if (graphics1.Attributes["AsBuilt_Date"] is Nullable)
                           


                        {



                            Groups1 = graphicsLayer.Graphics.GroupBy(graphic => (DateTime)graphic.Attributes["AsBuilt_Date"],
                                            (date, graphics) => new AttributeGroup
                                           {

                                               Key = date.ToString(),
                                               //   GISDATE = DateTime.ParseExact(date.ToString(), "yyyyMMdd", System.Globalization.CultureInfo.CurrentCulture),                            
                                               // Key = String.Format("{0:####-##-##}", date),
                                               Count = graphics.Count(),
                                               //    Sum = graphics.Select(g => (int16)g.Attributes["DOW"]).Sum(),
                                               Graphics = graphics
                                           }).OrderBy(group => group.Key).ToArray();

                        }
                    }
                }

My code doesn't fail now but if doesn't report back the/graph the none null fields. Maybe I need to assign the null records a value?? Thanks for the help. Anymore would be much appreciated.

Dave

\

JMcNeil

Something like this:

   foreach (Graphic graphic in graphicsLayer.Graphics)
                    {
                        if (graphic.Attributes["AsBuiltDate"] == "Null")
                        {
//DO SOMETHING IF NULL
}
}

JAY

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