仅当所有属性都具有值时，模型才为空

Question

我的API使用ASP.Net Core 2，前端使用Angular 4.4.2。

我有一个包含8个字符串属性的模型类，但只需要其中一个属性。仅当所有模型属性都具有值时，我的模型才会被绑定。当我发布数据时，我确保发送空字符串而不是null值，但即使一个属性没有值，我的模型仍为null。

使用MVC，如果JSON对象和模型中的属性具有不同的名称，则会出现此问题，但如果字符串为空甚至null则不会。

C＃模型类：

public class CustomerModel
{
    public long Id { get; set; }  // reusing the same model for edit and setting this to 0 when posting a new customer
    public string Title { get; set; }
    public string Address { get; set; }
    public string Phone { get; set; }
    public string Mail { get; set; }
    public string ContactName { get; set; }
    public string ContactSurname { get; set; }
    public string ContactPhone { get; set; }
    public string ContactMail { get; set; }
}

动作签名：

 public async Task<ActionResult> PostCustomer([FromBody] CustomerModel model)

发布帖子的角色TS代码：

postCustomer() {
    this.createCustomer();
    if (this.edit) {
        this.customerService.editCustomer(this.customer).subscribe(() => {
                this.dialogRef.close();
            },
            reject => {
                console.log(reject);
            });
    } else {
        this.customerService.postCustomer(this.customer).subscribe(() => {
                this.dialogRef.close();
            },
            reject => {
                console.log(reject);
            });
    }
}   

createCustomer() {
    const customer = this.customerForm.value;  // using reactive forms
    this.customer = new Customer(this.edit ? this.customer.id : 0,
            customer.title,
            customer.address,
            customer.phone,
            customer.mail,
            customer.contactName,
            customer.contactSurname,
            customer.contactPhone,
            customer.contactMail
        );  

}

电话会议：

  postCustomer(customer: Customer) {
    return this.httpClient.post(`/Api/Customer/Post`, customer);
}

Request payload

{"id":0,"title":"ssss","address":"","phone":"","mail":"","contactName":"","contactSurname":"","contactPhone":"","contactMail":""}