如何从其他模型获取数据并实现根据所选办公室自动填充墨盒信息

Great question—let's break this down into actionable steps to solve both your requirements, starting with a small model tweak that'll make your data more reliable long-term.

Step 1: Refactor Models for Better Data Integrity #

Right now, your Order stores the office name as a string, which is fragile—if an office gets renamed, existing orders will show outdated names and lose their reliable link to the correct cartridge. Instead, we'll use the office's Id as a foreign key:

Office.cs (no changes needed, just for reference):

public class Office {
    public int Id { get; set; }
    public string Name { get; set; } = "";
    public string Cartridge { get; set; } = "";
}

Updated Order.cs:

public class Order {
    public int Id { get; set; }
    public DateTime Created { get; set; }
    public int OfficeId { get; set; } // Store office ID instead of name
    public string Cartridge { get; set; } = "";
    // Optional: Add navigation property if using EF Core for easier querying
    public Office? Office { get; set; }
}

Step 2: Auto-Fill Cartridge on Office Selection (Create/Edit Form) #

We'll use JavaScript to listen for dropdown changes and populate the cartridge field. You have two solid options here:

Option A: Client-Side (Faster, No API Call)

Pass full office data to the view, then map IDs to cartridges for instant lookup:

Update OrdersController.cs (EditOrder GET method):

[HttpGet]
public IActionResult EditOrder(int? id) {
    var offices = _repo.GetAllOffices();
    // Use Office.Id as the dropdown value, Name as the display text
    ViewBag.Offices = new SelectList(offices, "Id", "Name");
    ViewBag.OfficeData = offices; // Send full office data to the view

    if (id == null) return View(new Order());
    else {
        var order = _repo.GetOrder((int)id);
        return View(order);
    }
}

Update the EditOrder View:
Add a disabled cartridge input (so users can't edit it) and the JavaScript to handle the dropdown:

@model Order
<div>
    <form asp-controller="Orders" asp-action="EditOrder" method="post">
        <input asp-for="Id" type="hidden" />
        <input asp-for="Created" type="hidden" />
        <div>
            <label>Your office</label>
            <select asp-for="OfficeId" asp-items="ViewBag.Offices"></select>
        </div>
        <div>
            <label>Cartridge</label>
            <input asp-for="Cartridge" type="text" disabled />
        </div>
        <input type="submit" value="Send" />
    </form>
</div>

<script>
    // Serialize office data from ViewBag into a JS object
    const officeData = @Html.Raw(Json.Serialize(ViewBag.OfficeData));
    const cartridgeMap = {};
    officeData.forEach(office => {
        cartridgeMap[office.id] = office.cartridge;
    });

    // Handle dropdown changes
    const officeSelect = document.querySelector('#OfficeId');
    const cartridgeInput = document.querySelector('#Cartridge');

    officeSelect.addEventListener('change', () => {
        cartridgeInput.value = cartridgeMap[officeSelect.value] || '';
    });

    // Initialize cartridge field when editing an existing order
    document.addEventListener('DOMContentLoaded', () => {
        if (officeSelect.value) {
            cartridgeInput.value = cartridgeMap[officeSelect.value] || '';
        }
    });
</script>

Option B: Server-Side API Call (For Dynamic Data)

If office data changes frequently, create an API endpoint to fetch the cartridge by office ID:

Add to OrdersController.cs:

[HttpGet("GetCartridgeByOfficeId")]
public IActionResult GetCartridgeByOfficeId(int officeId) {
    var office = _repo.GetOffice(officeId);
    if (office == null) return NotFound();
    return Ok(new { Cartridge = office.Cartridge });
}

Update the View's Script:

<script>
    const officeSelect = document.querySelector('#OfficeId');
    const cartridgeInput = document.querySelector('#Cartridge');

    officeSelect.addEventListener('change', async () => {
        const officeId = officeSelect.value;
        if (!officeId) {
            cartridgeInput.value = '';
            return;
        }

        const response = await fetch(`/Orders/GetCartridgeByOfficeId?officeId=${officeId}`);
        if (response.ok) {
            const data = await response.json();
            cartridgeInput.value = data.Cartridge;
        }
    });

    // Initialize for existing orders
    document.addEventListener('DOMContentLoaded', async () => {
        const officeId = officeSelect.value;
        if (officeId) {
            const response = await fetch(`/Orders/GetCartridgeByOfficeId?officeId=${officeId}`);
            if (response.ok) {
                const data = await response.json();
                cartridgeInput.value = data.Cartridge;
            }
        }
    });
</script>

Secure the Post Method:
To prevent client-side tampering, override the cartridge value from the database when saving:

[HttpPost]
public async Task<IActionResult> EditOrder(Order order) {
    if (order.Id > 0) {
        var existingOrder = _repo.GetOrder(order.Id);
        if (existingOrder != null) {
            existingOrder.OfficeId = order.OfficeId;
            existingOrder.Cartridge = _repo.GetOffice(order.OfficeId)?.Cartridge ?? "";
            _repo.UpdateOrder(existingOrder);
        }
    } else {
        order.Cartridge = _repo.GetOffice(order.OfficeId)?.Cartridge ?? "";
        _repo.AddOrder(order);
    }
    if (await _repo.SaveChangesAsync()) return RedirectToAction("Orders");
    else return View(order);
}

Step 3: Show Correct Cartridge in Order List #

Now that we're storing OfficeId, we have two clean ways to display the cartridge:

Option 1: Use EF Core Navigation Properties

Update your repository's GetAllOrders method to include the Office navigation property:

public IEnumerable<Order> GetAllOrders() {
    return _context.Orders.Include(o => o.Office).ToList();
}

Update the Orders View:

@model IEnumerable<Order>
<table>
    <thead>
        <tr>
            <th>Created Date</th>
            <th>Office</th>
            <th>Cartridge</th>
        </tr>
    </thead>
    <tbody>
        @foreach (var order in Model) {
            <tr>
                <td>@order.Created.ToString("yyyy-MM-dd HH:mm")</td>
                <td>@order.Office?.Name ?? "Unknown Office"</td>
                <td>@order.Office?.Cartridge ?? "No Cartridge Assigned"</td>
            </tr>
        }
    </tbody>
</table>

Option 2: Map Cartridges in the Controller (No Navigation Properties)

If you don't want to use navigation properties, fetch offices and map cartridges to orders in the controller:

public IActionResult Orders(int id) {
    var orders = _repo.GetAllOrders();
    var officeLookup = _repo.GetAllOffices().ToDictionary(o => o.Id, o => o);
    
    foreach (var order in orders) {
        if (officeLookup.TryGetValue(order.OfficeId, out var office)) {
            order.Cartridge = office.Cartridge;
        }
    }
    return View(orders);
}

Then your existing view code @order.Cartridge will work as expected.

Quick Tips #

• Always validate that the OfficeId exists in the database before saving orders to avoid invalid data.
• Using office IDs instead of names makes your system more robust—names can change, but IDs should remain consistent.

内容的提问来源于stack exchange，提问作者Joseph