在blazor中使用自定義組件時，在注入的差異服務中呼叫HttpContextAccesor后為null

我已經研究了一個 blazor 組件的屬性拼貼，我還沒有將它的類定義為繼承 ComponentBase，但我已經設定了一些屬性欄位來分配 html 屬性，然后每當 HttpContextAccesor 被注入（它回圈 3-4 次在第一個服務的建構式中注入，在第二個服務中只注入兩次，然后呼叫該方法以使用第一個服務的 API，然后當它完成并呼叫第二個服務時，背景關系訪問器為空

這里定義了自定義組件（子組件）

<input   required="@InputParameters["required"]" max="@InputParameters["max"]" maxlength="@InputParameters["maxlength"]"  
       placeholder="@InputParameters["placeholder"]" size="@InputParameters["min"]"
       value="@InputParameters["value"]" min="@InputParameters["min"]" name="@NameInput"  />

@code {

    [Parameter]
    public Dictionary<string, object> InputParameters { get; set; } = new Dictionary<string, object>
    {
        {"required","required" },
        {"placeholder","text place holder" },
        {"size", 100 },
        {"maxlength",100 },
        {"max",100 },
        {"min",0 },
        {"value",null }
    };

    [Parameter]
    public string NameInput { get; set; }

}

這是父組件

@page "/EditEmployee/{Id:int}"
@inherits EditEmployeeBase
@using SharedRazorClassLibrary.Components;
@using EmployeeManagement.Models; 
<h3>EditEmployee</h3>

<label>Time Elapsed: @ElapsedTime </label>
<EditForm Model="Employee" OnValidSubmit="SaveEmployeeDetails" OnInvalidSubmit="CheckErrors">
    <DataAnnotationsValidator />
    <MultiParameterComponent InputParameters="@(new Dictionary<string, object> {
                                                {"size",120 },
                                                {"placeholder","Hello"},
                                                {"maxlength",500 },
                                                {"max",500 },
                                                {"min",1 },
                                                {"value",null }
                                            })" NameInput="CustomMultiInput"></MultiParameterComponent>
    <div  row>
        <label for="@Employee.FirstName" > </label>
        <div >
            <InputText @bind-Value="Employee.FirstName"></InputText>
            <ValidationMessage For="@(() => Employee.FirstName)" />
        </div>
    </div>
    <div  row>
        <label for="@Employee.LastName" ></label>
        <div >
            <InputText @bind-Value="Employee.LastName"></InputText>
            <ValidationMessage For="@(() => Employee.LastName)" />
        </div>
    </div>

    <div  row>
        <label for="@Employee.DepartmentId" ></label>
        <div >
            <CustomInputSelect @bind-Value="Employee.DepartmentId">
                @foreach (var dept in Departments)
                {
                    <option value="@dept.DepartmentId">@dept.DepartmentName</option>
                }
            </CustomInputSelect>
            <ValidationMessage For="@(() =>Employee.DepartmentId)" />
        </div>
    </div>
    <div >
        <label for="@Employee.Gender"> Gender </label>
        <div >
            <CustomInputSelect @bind-Value="Employee.Gender">
                @foreach (var gender in Enum.GetValues(typeof(Gender)))
                {
                    <option value="@gender">@gender</option>
                }

            </CustomInputSelect>

        </div>
    </div>
    <div  row>
        <label for="@Employee.DateOfBirth" ></label>
        <div >
            <InputDate @bind-Value="Employee.DateOfBirth" @bind-Value:format="dd/MM/YYYY"></InputDate>
        </div>
    </div>
    <div >
        <label for="@Employee.Email">Email</label>
        <InputText @bind-Value="@Employee.Email"></InputText>
        <ValidationMessage For="@(()=>Employee.Email)" />
    </div>
    <button type="submit">Submit</button>
    <a href="/DeleteEmployee/@Employee.EmployeeId" @onclick="DeleteEmployee" >Delete</a>

</EditForm>

這是 Startup 的服務注入

    services.AddRazorPages();
    services.AddServerSideBlazor();
    services.AddAutoMapper((config) => {
        config.AddProfile(typeof(EmployeeProfile));
    });
    services.AddHttpContextAccessor();
    services.AddSingleton<PathHelper>();
    //services.AddScoped<Microsoft.AspNetCore.Http.IHttpContextAccessor, Microsoft.AspNetCore.Http.HttpContextAccessor>();
    services.AddScoped<IEmployeeServices,EmployeeServices>();
    services.AddScoped<IDepartmentServices, DepartmentServices>();
    services.AddHttpClient<IEmployeeServices,EmployeeServices>().ConfigureHttpClient((sp, httpClient) => {
       

    });

so I wonder what could be causing that the second request makes the IHTTPContextAccesor interface to be null?

uj5u.com熱心網友回復：

奇怪的解決方案是以我注入它的相同順序注入介面

首先是 HttpClient，然后是 IHpttpContextAccessor，DI 似乎按預期作業，但我使用 HttpAccessor 作為瞬態，因為它在啟動時注冊服務時拋出例外

標籤：asp.net-core blazor blazor-server-side asp.net-blazor

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