<tr *ngFor="let project of projects">
  <td>{{ project.name }}</td>
  <td>{{ project.description }}</td>
  <td>
    <button type="button" class="btn btn-sm btn-primary bigger" (click)="onEditProject(project.id)"><i class="fa fa-pencil-square-o" aria-hidden="true"></i> Edit</button>
  </td>
  <td>

    <ng-container *ngIf="getProjectType(project.id)">
      <ng-template *ngIf="getProjectType(project.id) === 'new'">
        <button type="button" class="btn btn-sm btn-primary" (click)="onCreateBOM(project.id)"><i class="fa fa-plus-circle" aria-hidden="true"></i> Create Bill of Material</button>
      </ng-template>

      <ng-template  *ngIf="getProjectType(project.id) === 'exist'">
        <button type="button" class="btn btn-sm btn-success" (click)="onEditBOM(project.id)"><i class="fa fa-pencil-square-o" aria-hidden="true"></i> Edit Bill of Material</button>
      </ng-template>

    </ng-container>
  </td>
</tr>

public getProjectType(project_id): 'new' | 'exist' | null {
        return project_id.material_projects.id === project_id ? 'new'
            : project_id.material_projects.id === project_id ? 'exist'
            : null;
    }