Question

I’m trying to define a self referencing relationship for a workflow step where that step is not available to be kicked off until all of its dependent steps have been completed. A step can have zero or many dependencies. I have the following but, EF doesn’t map this correctly. Instead it creates the following table which does not meet my needs. How can I achieve this?

Class:

public class WorkflowStepDefinition : EntityBase, IAudited {
    [Key]
    public int WorkflowStepDefinitionId { get; set; }
    [MaxLength(100)]
    public string Name { get; set; }
    public string Description { get; set; }
    public int WorkflowDefinitionId { get; set; }        
    public virtual WorkflowDefinition WorkflowDefinition { get; set; }
    public virtual IList<WorkflowStep> WorkflowSteps { get; set; }
    public virtual IList<WorkflowStepDefinition> DependsOn { get; set; }
    public AuditDetails Audit { get; set; }        
}

Table Def:

CREATE TABLE [dbo].[WorkflowStepDefinitions](
    [WorkflowStepDefinitionId] [int] IDENTITY(1,1) NOT NULL,
    [Name] [nvarchar](100) NOT NULL,
    [Description] [nvarchar](max) NULL,
    [WorkflowDefinitionId] [int] NOT NULL,
    [Audit_CreatedBy] [nvarchar](max) NOT NULL,
    [Audit_DateCreated] [datetimeoffset](7) NOT NULL,
    [Audit_UpdatedBy] [nvarchar](max) NULL,
    [Audit_DateUpdated] [datetimeoffset](7) NULL,
    [WorkflowStepDefinition_WorkflowStepDefinitionId] [int] NULL,
 CONSTRAINT [PK_WorkflowStepDefinitions] PRIMARY KEY CLUSTERED 
(
    [WorkflowStepDefinitionId] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

ALTER TABLE [dbo].[WorkflowStepDefinitions]  WITH CHECK ADD  CONSTRAINT [FK_WorkflowStepDefinitions_WorkflowDefinitions_WorkflowDefinitionId] FOREIGN KEY([WorkflowDefinitionId])
REFERENCES [dbo].[WorkflowDefinitions] ([WorkflowDefinitionId])
ON DELETE CASCADE
GO

ALTER TABLE [dbo].[WorkflowStepDefinitions] CHECK CONSTRAINT [FK_WorkflowStepDefinitions_WorkflowDefinitions_WorkflowDefinitionId]
GO

ALTER TABLE [dbo].[WorkflowStepDefinitions]  WITH CHECK ADD  CONSTRAINT [FK_WorkflowStepDefinitions_WorkflowStepDefinitions_WorkflowStepDefinition_WorkflowStepDefinitionId] FOREIGN KEY([WorkflowStepDefinition_WorkflowStepDefinitionId])
REFERENCES [dbo].[WorkflowStepDefinitions] ([WorkflowStepDefinitionId])
GO

ALTER TABLE [dbo].[WorkflowStepDefinitions] CHECK CONSTRAINT [FK_WorkflowStepDefinitions_WorkflowStepDefinitions_WorkflowStepDefinition_WorkflowStepDefinitionId]
GO

Edit:
Ideally I think I’d like something that produces a join table such as:

CREATE TABLE [dbo].[WorkflowStepDefinitionDependencies](
    WorkflowStepDefinitionId int NOT NULL,
    DependencyId int NOT NULL
)

Answer 1

As mentioned in comment you can achieve this with fluent API which also gives you possibility to name your junction table and FKs in the junction table:

modelBuilder.Entity<WorkflowStepDefinition>()
            .HasMany(w => w.DependsOn)
            .WithMany()
            .Map(mc =>
                {
                     mc.ToTable("WorkflowStepDefinitionDependencies", "dbo");
                     mc.MapLeftKey("WorkflowStepDefinitionId");
                     mc.MapRightKey("DependencyId");
                });