An item with the same key has already been added.

Question

2.00/5 (2 votes)

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C#

var result = from d in data
                         select new Dictionary<string, string>()
             {
                { "Name", (string)d.Attribute("Name") },
                 { "MappedName", (string)d.Attribute("MappedName") },
                 { "DataType", (string)d.Attribute("DataType") },
                 { "length", (string)d.Attribute("length") }

             };

            foreach (var item in result)
            {
                foreach (var y in item)
                {
                    hash.Add(y.Key, y.Value);
                }
            }

getting error as :An item with the same key has already been added.

my xml doc:

XML

<ColumnNames>
<Column Name="RequestDate" MappedName="@A" DataType="Datetime" length="" />
<Column Name="AgentNumber" MappedName="@B" DataType="varchar"  length="4" />
</ColumnNames>

Posted 6-Aug-13 20:42pm

valluru's

Updated 6-Aug-13 20:56pm

v2

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Comments

Naz_Firdouse 7-Aug-13 2:51am

there may exists duplicate Name attributes in your data...
verify that else assign a value as a key which is unique in your collection

Sergey Alexandrovich Kryukov 7-Aug-13 2:52am

What is unclear in this message? Do you understand that the keys in key-indexed (associative) containers should be unique?
Also, pat attention that the dictionary with values identical to keys makes no sense at all. You should use HashSet then.
—SA

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**Joezer BH** · Answer 1 · 2013-08-06T21:11:00

The exception is thrown in this line:

C#

hash.Add(y.Key, y.Value);

if y.Key is a value already existing in the (unique) Key collection of your Hashtable, it will of course throw that exception.

It is your duty to make sure that you insert a value which is unique OR reconsider you application specification, (e.g. using other data structures that allow duplicates etc)

Good luck,
Edo

Pheonyx · Answer 2 · 2013-08-06T21:11:00

The error simply means that because your dictionaries all look like this:

{ "Name", (string)d.Attribute("Name") },
                 { "MappedName", (string)d.Attribute("MappedName") },
                 { "DataType", (string)d.Attribute("DataType") },
                 { "length", (string)d.Attribute("length") }

When you adding them to the hashtable the keys it tries to use are:

Name, MappedName, DataType, Length

Once it has added the first dictionary in the results set, those keys then exist so when it tries to add the next one it errors because it cannot add an entry with those keys again.

I would suggest some sort of dynamic approach to key generation to that they are unique each time.

An item with the same key has already been added.

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