If you have a custom field that only accepts values from a lookup table, you cannot assign values the way you would with a regular custom field value. To start we will retrieve the ‘InternalName‘ property of the custom field, the value should look like the variable ‘customFieldInternalName‘ below.
To write our article, we used a project. So first check out the project to be able to make changes to the custom fields. We will then create a variable of the lookup table, and retrieve its values. We are looking for a specific entry in the lookup table, of which we will save the ‘InternalName’ property for later use. We stored the value of the ‘InternalName’ property in a variable called ‘invoicedInternalName’.
The custom field only accepts an array of strings as values. These strings are the values of the ‘InternalName‘ property of the entry in the lookup table.
All is left is to check in and publish your project in this sample. This method also works for tasks and resources.
// InternalName of the custom field
string customFieldInternalName = "Custom_d6f1eabe76f5e64580ed00126ee74a0e"
// Checkout the project
DraftProject draftProject = publishedProject.Checkout()
// Create a shortcut for the lookup table and load all lookup tables
var luts = projContext.LookupTables;
projContext.Load(luts);
projContext.ExecuteQuery();
// Just retrieve the lookup table we need
var lut = luts.GetByGuid(new Guid("73897025-0aa0-e511-80eb-00155d0ce209"));
// Retrieve a specific entry
var entry = lut.Entries.Single(e => e.FullValue.Equals("Invoiced"));
// Get its internal name from the InternalName property
var invoicedInternalName = entry.InternalName;
// and store it in an array of strings
string[] lutInvoiceStatusValues = {invoicedInternalName};
// Apply it to the checked out project.
draftProject[customFieldInternalName] = lutInvoiceStatusValues
// Check project in and publish
// ...