在我的Xamarin应用程序中,有一个选择器,该选择器从数据库获取银行列表,而该数据库通过API获取银行详细信息。
一切正常,但是现在,我想更新数据库,如果新的银行添加到API中,我想将它们添加到现有数据库中。
我写了这个小代码,但是问题是,它首先从数据库中输出所有现有记录,然后打印新记录,是记录总数的很多倍,例如(如果有十条记录,它将每条记录打印十条记录)次)。
ViewModel.cs
// Load all Banks into a List
var getBanks = await App.Database.GetBankAsync();
// Update the Bank Details where new Banks doesn't exist in the Database
List<Bank> updateBanks = new List<Bank>();
foreach (Banks i in obj.banks)
{
foreach (var record in getBanks.Where(c => c.Name != i.alias.name))
{
updateBanks.Add(new Bank { Name = i.alias.name, Status = "Not Registered" });
}
}
foreach (var bank in updateBanks)
{
await App.Database.SaveBankAsync(bank);
}
// Load all Banks into a List
var getBanksUpdated = await App.Database.GetBankAsync();
// Load the Banks whose Status is "Not Registered"
foreach (var record in getBanks.Where(c => c.Status == "Not Registered")
{
_bankList.Add(record);
}
public class Alias
{
public string name { get; set; }
}
public class Banks
{
public Alias alias { get; set; }
public string id { get; set; }
}
public class RootObject
{
public List<Banks> banks { get; set; }
}
通过API获取数据
{
success: true,
banks: [
{
alias: {
name: "Bank 1",
Address: "Earth"
},
endpoint: {
uri: "http://127.0.0.1:0000"
},
state: "Registered",
createdAtUtc: "2021-01-19T13:55:12.2318662",
updatedAtUtc: "2021-01-19T13:55:14.9944042"
},
]
}
从API获取数据的代码
HttpClient httpClient = new HttpClient(new NativeMessageHandler());
Uri getDataBanks = new Uri(string.Format("http://127.0.0.1:0000/Banks"));
HttpResponseMessage restponseBanks = await httpClient.GetAsync(getDataBanks);
string contentBanks = await restponseBanks.Content.ReadAsStringAsync();
RootObject obj = JsonConvert.DeserializeObject<RootObject>(contentBanks);
// get the names of all existing banks
List<string> names= obj.banks.Select(u => u.Name).ToList();
// get the names of all banks taken from the API
List<string> names_new= getBanks.Select(u => u.Name).ToList();
foreach (var record in names_new)
{
//check if the bank is exists or not
if(! names.contains(record)
{
updateBanks.Add(new Bank { Name = record.alias.name, Status = "Not Registered" });
}
}
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