角度7-选择一个下拉列表的值将更新其他下拉列表的值

我的Angular7应用程序中有一个HTML,在该应用程序中,每行显示相同的下拉列表。选择一个下拉列表会更改另一个下拉列表的值。如何使所选内容对该特定下拉列表唯一。

HTML

<div class="upload-table">
            <table id="table1" class="center" >

                <tbody class="upload-name-style">
                    <tr *ngFor="let item of files; let i=index">
                        <td> <input kendoTextBox [(ngModel)]="item.relativePath" style="width: 350px" /></td>
                        <td><kendo-dropdownlist style="width:350px" [(ngModel)]="selectedDocumentItem"  [data]="DocumentTypes"
                            [filterable]="false" textField="Name"  valueField="Id">
                        </kendo-dropdownlist></td>
                    </tr>
                </tbody>
            </table>


        </div>

部件代码

DocumentTypes: any = {};
    selectedDocumentItem: { 'Id': any; 'Name': any; };

public getDocumentTypes() {
        this.documentUploadService.getDocumentTypes()
            .subscribe(data => {
                this.DocumentTypes = data;
                this.DocumentTypesForDropDown = this.DocumentTypes.map(x => x.Name);
                this.getDocumentUploadDetails();
                this.setGridOptions();
                this.setColumns();
            },
                err => {
                    this.Error = 'An error has occurred. Please contact BSG';
                },
                () => {
                });

    }