Can we add duplicates to dictionary?

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Posted on by meenoo

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Hi,

I have a dictionary(Dictionary<string, Guid>) which does not allow duplicates to be added. Is there a way that we can add duplicates into it?

Here is my code snippet which fails if there is a key already in the dictionary.

Dictionary<string, Guid> dictLookupLocation = new Dictionary<string, Guid>();

                  
                   QueryExpression locationQuery = new QueryExpression("new_locations");
                   locationQuery.ColumnSet = new ColumnSet(true);
                   EntityCollection locationCollection = CRMHelper.GetCRMService().RetrieveMultiple(locationQuery);

                   foreach (Entity location in locationCollection.Entities)
                   {
                       string locationName = location.GetAttributeValue<string>("new_office");

                       if (!dictLookupLocation.ContainsKey(locationName))
                       {
                           dictLookupLocation .Add(locationName, location.Id);
                       }
                   }

Thanks for any help.

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Aiden Kaskela 19,696 on at

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Hi,

A dictionary in C# has one key which returns one value - no exceptions (unless the key doesn't exist, they you'll get an Exception. Haha). In your case, the key is a name and the Value is an Guid. If you need multiple values for one key, you can change the type of dictionary so the one value you're returning is a list object, of Guids. I updated your code:

Dictionary<string, List<Guid>> dictLookupLocation = new Dictionary<string, List<Guid>>(); QueryExpression locationQuery = new QueryExpression("new_locations"); locationQuery.ColumnSet = new ColumnSet(true); EntityCollection locationCollection = CRMHelper.GetCRMService().RetrieveMultiple(locationQuery); foreach (Entity location in locationCollection.Entities) { string locationName = location.GetAttributeValue<string>("new_office"); if (!dictLookupLocation.ContainsKey(locationName)) { dictLookupLocation.Add(locationName, new List<Guid>()); } dictLookupLocation[locationName].Add(location.Id); }

When this runs, you'll have one dictionary entry for each location name, but if you get the Value for a key it will be a list of all IDs.

Hope this helps! I'd appreciate if you would mark this as a Verified answer.

Thanks,

Aiden

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Dhaval mistry 810 on at

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I would suggest use List<KeyValuePair<string, Guid>> instead of Dictionary<string, Guid>

KeyValuePair can hold duplicate value.

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Aiden Kaskela 19,696 on at

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KVP doesn't hold duplicates because each KVP is unrelated from the others - you wouldn't have duplicates you'd just have two Key Value Pairs. You'd still need a collection to hold them, even if it's just a list. Then to access the values you'd need to select all the KVP from the list based on the key of each pair. I'd use a dictionary myself.

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Dhaval mistry 810 on at

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Correcting myself List<KeyValuePair<string, Guid>>()

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Aileen Gusni 44,524 on at

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Hi Meeno

The dictionary purpose is to create a pair (unique pair) between key and value so you cant use this for duplicate.

You can use generic list, array, or nested dictionary key pair for this.

Thanks

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