LINQ to Sharepoint InsertOnSubmit问题

Question

例如，我有一个名为ProductPrice的列表，它有3列，ProductName (即标题)、ProductPrice和ProductType。

• ProductName是一个字符串
• ProductPrice是一种货币(双倍)
• ProductType是ProductTypes列表上的一个LookUp

通常，如果不包含LookUp列，这对我来说很容易，但我不知道如何处理插入时的查找列。

我试过了，但是它返回了一个错误Specified cast is not valid.

下面是当前的代码

EntityList<ProductTypeItem> ProductTypes = dc.GetList<ProductTypeItem>("ProductType");

ProductItem newProduct = new ProductItem();

newProduct.Title = txtProductName.Text;
newProduct.ProductPrice = double.Parse(txtProductPrice.Text); 
newProduct.ProductType = (from a in ProductTypes where a.Title == ddProductType.SelectedItem.Text select a).FirstOrDefault();

dc.Product.InsertOnSubmit(newProduct);
dc.SubmitChanges();   

我将如何处理newProduct.ProductType，因为这里是错误发生的地方。

请注意，ddProductType DataSource是ProductType List，在DataTextField和DataValueField中使用Title

Answer 1

它现在起作用了，这就是解决办法。

EntityList<Item> ProductTypes = dc.GetList<Item>("ProductType");
Item oProductType = (from a in ProductTypes where a.Title == ddProductType.SelectedItem.Text select a).FirstOrDefault();
ProductItem newProduct = new ProductItem();

newProduct.Title = txtProductName.Text;
newProduct.ProductPrice = double.Parse(txtProductPrice.Text);
newProduct.ProductType = (ProductTypeItem)oProductType;

dc.Product.InsertOnSubmit(newProduct);
dc.SubmitChanges();   

我更改的唯一方法是将产品类型初始化为Item，而不是ProductTypeItem，，然后将其转换为ProductTypeItem，现在它可以工作了

Answer 2

这也许能帮你解决问题。第一个示例说明如何使用指向现有数据的链接进行插入。这个示例代码应该为您提供足够的提示，帮助您解决问题：

AdventureWorksDataContext db = new AdventureWorksDataContext();

// LINQ query to get StateProvince
StateProvince state = (from states in db.StateProvinces
                       where states.CountryRegionCode == "AU" && states.StateProvinceCode == "NSW"
                       select states).FirstOrDefault();
// LINQ function to get AddressType
AddressType addrType = db.AddressTypes.FirstOrDefault(s => s.Name == "Home");

Customer newCustomer = new Customer()
{
    ModifiedDate= DateTime.Now,
    AccountNumber= "AW12354", 
    CustomerType='I',
    rowguid= Guid.NewGuid(),
    TerritoryID= state.TerritoryID    // Relate record by Keys
};
Contact newContact = new Contact()
{
    Title = "Mr",
    FirstName = "New",
    LastName = "Contact",
    EmailAddress = "newContact@company.com",
    Phone = "(12) 3456789", 
    PasswordHash= "xxx",
    PasswordSalt= "xxx",
    rowguid = Guid.NewGuid(),
    ModifiedDate = DateTime.Now
};
Individual newInd = new Individual()
{
    Contact= newContact,    // Relate records by objects (we dont actually know the Keys for the new records yet)
    Customer= newCustomer,
    ModifiedDate= DateTime.Now
};
Address newAddress = new Address()
{
    AddressLine1= "12 First St",
    City= "Sydney",
    PostalCode= "2000", 
    ModifiedDate=DateTime.Now,
    StateProvince= state,
    rowguid = Guid.NewGuid()
};

// Link our customer with their address via a new CustomerAddress record
newCustomer.CustomerAddresses.Add(new CustomerAddress() { Address = newAddress, Customer = newCustomer, AddressType = addrType, ModifiedDate = DateTime.Now, rowguid = Guid.NewGuid() });

// Save changes to the database
db.SubmitChanges();

Answer 3

我不熟悉Linq到SharePoint，但我假设它类似于客户端对象模型。如果是这样的话，您需要使用FieldLookupValue作为newProduct.ProductType的值，并使用查找的ID作为值：

newProduct.ProductType = new FieldLookupValue { LookupId = 1 };

这意味着您需要在ListID查询中访问查找值的ProductTypes。