Generic way to get OptionSet value or Text in Dynamic 365 CRM

Here are C# methods

public static string GetOptionSetTextFromValue(string entityName, string attributeName, int value)

{

    string optionsetText = string.Empty;

    var attributeRequest = new RetrieveAttributeRequest

    {

        EntityLogicalName = entityName,

        LogicalName = attributeName,

        RetrieveAsIfPublished = true

    };

    // Execute the request.

    var attributeResponse = (RetrieveAttributeResponse)service.Execute(attributeRequest);

    // Access the retrieved attribute.

    var attributeMetadata = (EnumAttributeMetadata)attributeResponse.AttributeMetadata;

    // Get the current options list for the retrieved attribute.

    var optionList = (from o in attributeMetadata.OptionSet.Options

                        select new { Value = o.Value, Text = o.Label.UserLocalizedLabel.Label }).ToList();

    optionsetText = optionList.Where(o => o.Value == value)

                                .Select(o => o.Text)

                                .FirstOrDefault();

    return optionsetText;

}

public static int GetOptionSetValueFromLabel(string entityName, string attributeName, string optionsetText)

{

    int optionSetValue = 0;

    var attributeRequest = new RetrieveAttributeRequest()

    {

        EntityLogicalName = entityName,

        LogicalName = attributeName,

        RetrieveAsIfPublished = true

    };

    // Execute the request.

    var attributeResponse = (RetrieveAttributeResponse)service.Execute(attributeRequest);

    // Access the retrieved attribute.

    var picklistAttributeMetadata = (PicklistAttributeMetadata)attributeResponse.AttributeMetadata;

    // Get the current options list for the retrieved attribute.

    OptionSetMetadata optionsetMetadata = picklistAttributeMetadata.OptionSet;

    var optionList = (from o in optionsetMetadata.Options

                        select new { Value = o.Value, Text = o.Label.UserLocalizedLabel.Label }).ToList();

    optionSetValue = (int)optionList.Where(o => o.Text.ToLower() == optionsetText.ToLower())

                                .Select(o => o.Value)

                                .FirstOrDefault();

    return optionSetValue;

}

Here is REST API Way

We need to include Formatted Values to get OptionSet Labels

var req = new XMLHttpRequest();

var fetchStatement = "/api/data/v9.1/contacts(EF5D6F09-399A-E811-A966-000D3AB0C08C)?$select=cm_language";

req.open("GET", Xrm.Page.context.getClientUrl() + fetchStatement, false);

req.setRequestHeader("OData-MaxVersion", "4.0");

req.setRequestHeader("OData-Version", "4.0");

req.setRequestHeader("Accept", "application/json");

req.setRequestHeader("Content-Type", "application/json; charset=utf-8");

req.setRequestHeader("Prefer", "odata.include-annotations=\"*\"");

req.onreadystatechange = function () {

    if (this.readyState === 4) {

        req.onreadystatechange = null;

        if (this.status === 200) {

            var result = JSON.parse(this.response);

            //OptionSet Value

            var cm_language = result["cm_language"];

            //OptionSet Label (Text)

            var cm_language_formatted = result["cm_language@OData.Community.Display.V1.FormattedValue"];

        } else {

            Xrm.Utility.alertDialog(this.statusText);

        }

    }

};

req.send();

Here is a Form Script

Xrm.Page.getAttribute("cm_customerservicelanguage").getSelectedOption().value 

Xrm.Page.getAttribute("cm_customerservicelanguage").getSelectedOption().text