topic Re: Attribute Query - return Groups? in ArcGIS API for Silverlight Questions

Attribute Query - return Groups?

ducksunlimited — Thu, 07 Oct 2010 17:06:55 GMT

Dear All,

I used ESRI attribute query sample and returned all the values (commercial, commercial, agricultural, agricultural, etc) for that field. But I want only the groups (commericial, agricultural, etc) returned. How to construct the query so I can achieve this. thanks for the help,

Russel

Re: Attribute Query - return Groups?

JenniferNery — Sat, 11 Dec 2021 09:00:22 GMT

You can set your query's OutFields property so that it will return only the fields that you want it to return.

            query.OutFields.AddRange(new string[] { "FIELD_NAME" });

Re: Attribute Query - return Groups?

ducksunlimited — Sat, 11 Dec 2021 09:00:26 GMT

You can set your query's OutFields property so that it will return only the fields that you want it to return.
            query.OutFields.AddRange(new string[] { "FIELD_NAME" });

thanks for your reply!

I want to return only catogories for a field. For instance, I have a "LanUseType" field with values like commercial, agriculatural, wetlands, etc. How can I group by features using "LandUseType"? Help would be appreciated.

Russel

Re: Attribute Query - return Groups?

BrianPangtay — Wed, 13 Oct 2010 10:38:51 GMT

ESRI attribute queries are based on SQL queries. Since the ESRI API only allows one to specify the WHERE clause of a SQL query, I don't think one can perform a group query in this manner.

Using transaction SQL,

If you want grouping to perform calculations, then one would need a GROUP BY clause in the SQL query.

If you only want the unique values for a given field, then one would need a DISTINCT keyword in the SQL query.

Re: Attribute Query - return Groups?

JenniferNery — Wed, 13 Oct 2010 13:29:20 GMT

Do you mean this?

In this feature service http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/HomelandSecurity/operations/FeatureServer/0

ftype is CodedValueDomain, each number represent a category that can be one of the following values (Hydro-Meteorlogical, Public Health, ... Vehicle)

If I want to see only features that are "Vehicle", my query's Where is "ftype = 10801"

Re: Attribute Query - return Groups?

ducksunlimited — Wed, 13 Oct 2010 17:03:59 GMT

Do you mean this?

In this feature service http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/HomelandSecurity/operations/FeatureServer/0

ftype is CodedValueDomain, each number represent a category that can be one of the following values (Hydro-Meteorlogical, Public Health, ... Vehicle)

If I want to see only features that are "Vehicle", my query's Where is "ftype = 10801"

Thanks for the reply. I would like to return each group (like Hydro-Meteorlogical, Vehicle, etc) as a row in a datagrid, so users can select a row and zoom to that group (multiple polygons). Can I construt the Query.Where clause to do this? Thanks,

Re: Attribute Query - return Groups?

JenniferNery — Sat, 11 Dec 2021 09:00:29 GMT

I think what you can do is first know the groups, which you can do by:

  foreach (Field field in fl.LayerInfo.Fields)
   {
    if (field.Domain is CodedValueDomain)
    {
     CodedValueDomain domain = field.Domain as CodedValueDomain;
     foreach (var item in domain.CodedValues)
     {
//item.Key is an object this is what you need in your query

     }
    }
   }

If your FeatureLayer was HomelandSecurity as in my previous post, you can see that ftype is CodedValueDomain and you can perform your query where "ftype = 10801".

Re: Attribute Query - return Groups?

ducksunlimited — Sat, 11 Dec 2021 09:00:31 GMT

I think what you can do is first know the groups, which you can do by:
  foreach (Field field in fl.LayerInfo.Fields)
   {
    if (field.Domain is CodedValueDomain)
    {
     CodedValueDomain domain = field.Domain as CodedValueDomain;
     foreach (var item in domain.CodedValues)
     {
//item.Key is an object this is what you need in your query

     }
    }
   }
If your FeatureLayer was HomelandSecurity as in my previous post, you can see that ftype is CodedValueDomain and you can perform your query where "ftype = 10801".

Thanks for the help. I see this will work.

But CodedDomain is only supported in 2.0 not 1.2 right?

Re: Attribute Query - return Groups?

JenniferNery — Wed, 13 Oct 2010 19:30:54 GMT

Yes you're right CodedValueDomain is new to 2.0.