Create object-must-implement-iconvertible.md (#1095)

Author: DimitarNikolovv06

knowledge-base/object-must-implement-iconvertible.md

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+---
+title: Object must implement IConvertible
+description: "Learn why and when the 'Object must implement IConvertible' is thrown and how to resolve it in Telerik Reporting"
+type: troubleshooting
+page_title: MultiValue Parameter in ObjectDataSource Throws Error IConvertible
+slug: object-must-implement-iconvertible
+tags: ObjectDataSource, MultiValue, ReportParameter
+ticketid: 1612711
+res_type: kb
+---
+
+## Environment
+<table>
+    <tbody>
+        <tr>
+            <td>Product</td>
+            <td>Progress® Telerik® Reporting</td>
+        </tr>
+    </tbody>
+</table>
+
+
+## Description
+
+I have created an [ObjectDataSource]({%slug telerikreporting/designing-reports/connecting-to-data/data-source-components/objectdatasource-component/overview%}) component whose data method has a parameter that is of type `List<int>`. When I try to preview the report, I am met with the below error in place of the [data item]({%slug telerikreporting/designing-reports/connecting-to-data/data-items/overview%}) using said `ObjectDataSource`.
+
+## Steps to Reproduce
+
+1. Create an `ObjectDataSource` whose data method expects a list/array of primitive type as one of its parameters.
+1. Create a `MultiValue=True` [Report Parameter]({%slug telerikreporting/designing-reports/connecting-to-data/report-parameters/overview%}) and set its value to be passed to the parameter of the `ObjectDataSource`
+1. Set the value of the report parameter and preview the report.
+
+## Error Message
+
+`An error has occurred while resolving data source: Object must implement IConvertible`
+
+## Cause
+
+The `Multivalue` Report Parameters always return `Object[]`. As the received `Object[]` cannot be converted to `List<type>`, the corresponding `ObjectDataSource` Parameters cannot be correctly mapped to the Report Parameters.
+
+## Solution
+
+Change the type of the `ObjectDataSource` Parameters using `MultiValue` to `Object[]` in one of the following ways:
+
+- Through the [ObjectDataSource Wizard]({%slug telerikreporting/designing-reports/report-designer-tools/desktop-designers/tools/data-source-wizards/objectdatasource-wizard%})
+- Through the code behind:
+
+	````CSharp
+new Telerik.Reporting.ObjectDataSourceParameter("UserNames", typeof(object[]), "= Parameters.UserNames.Value"),
+````
+
+
+## See Also
+
+* [Using Parameters with the ObjectDataSource Component]({%slug telerikreporting/designing-reports/connecting-to-data/data-source-components/objectdatasource-component/using-parameters-with-the-objectdatasource-component%})
+* [Using Multivalue Parameters]({%slug telerikreporting/designing-reports/connecting-to-data/report-parameters/using-multivalue-parameters%})