I have a Front-End application that sends me Data to update my User (updatedUser). Since I don't want to send the whole Userdata, I'm only sending the data that has changed. Now I want to Update my Userdata with the changes provided, so I'd like to know if there is a more elegant way to do this than just a list of ifs/lets. I'm quite new to kotlin, so don't expect too much from me^^
Not so elegant way:
changeData.firstname?.let { updatedUser.firstname = it }
changeData.lastname?.let { updatedUser.lastname = it }
...
Expected (doesn't work - type mismatch):
updatedUser.copy(
firstname = changeData?.firstname,
lastname = changeData?.lastname,
...)
the reason you get a type mismatch is There is a string type and a string nullable type
var variableName:String = "myData" // if you want a non nullable
var variableName:String? = "myDataThatCouldBeNull" // if you want a string that could be null
Related
I have some code which looks like this, where param is of a data class type:
val options = if (param.language == null) {
param.copy(language = default())
} else {
param
}
Now, however, the language object has been moved into a hierarchy of nullable objects, so the check must look like this:
if (param.subObj?.nextObj?.language == null) { ... }
How do I use the copy idiom in this case?
One way to do this is:
val newParam = when {
param.subObj == null -> param.copy(subObj = SubObj(nextObj = NextObj(language = Language())))
param.subObj.nextObj == null -> param.copy(subObj = param.subObj.copy(nextObj = NextObj(language = Language())))
param.subObj.nextObj.language == null -> param.copy(subObj = param.subObj.copy(nextObj = param.subObj.nextObj.copy(language = Language())))
else -> param
}
I agree that this doesn't look very clean but this seems to be the only way to me, because at each step you need to check if the current property is null or not. If it is null, you need to use the default instance otherwise you need to make a copy.
Could you do something like this?
// you could create a DefaultCopyable interface if you like
data class SubObj(val prop1: Double? = null, val nextObj: NextObj? = null) {
fun copyWithDefaults() =
copy(prop1 = prop1 ?: 1.0, nextObj = nextObj?.copyWithDefaults() ?: NextObj())
}
data class NextObj(val name: String? = null) {
fun copyWithDefaults() = copy(name = name ?: "Hi")
}
I think you need a special function because you're not using the standard copy functionality exactly, you need some custom logic to define defaults for each class. But by putting that function in each of your classes, they all know how to copy themselves, and each copy function that works with other types can just call their default-copy functions.
The problem there though is:
fun main() {
val thing = SubObj(3.0)
val newThing = thing.copyWithDefaults()
println("$thing\n$newThing")
}
> SubObj(prop1=3.0, nextObj=null)
> SubObj(prop1=3.0, nextObj=NextObj(name=null))
Because nextObj was null in SubObj, it has to create one instead of copying it. But the real default value for name is null - it doesn't know how to instantiate one with the other defaults, that's an internal detail of NextObj. You could always call NextObj().copyWithDefaults() but that starts to look like a code smell to me - why isn't the default value for the parameter the actual default value you want? (There are probably good reasons, but it might mean there's a better way to architect what you're up to)
I try to save some data that it brings me from my view, which is a table, but I don't know why it throws me that error with the insert.
result of insert
this is my view:
table of view
this is my controller:
$checked_array = $_POST['id_version'];
foreach ($request['id_version'] as $key => $value) {
if (in_array($request['id_version'][$key], $checked_array))
{
$soft_instal = new Software_instalacion;
$soft_instal->id_instalacion = $instalaciones->id;
$soft_instal->id_historial = $historial->id;
$soft_instal->id_usuario = $request->id_usuario;
$soft_instal->id_version = $_POST['id_version'][$key];
$soft_instal->obs_software = $_POST['obs_software'][$key];
$soft_instal->id_tipo_venta = $_POST['id_tipo_venta'][$key];
$soft_instal->save();
}
}
id_tipo_venta seems to be an empty string which is apparently not valid.
You can try debugging what you get in :
var_dump($_POST['id_tipo_venta'][$key]);
die;
Your database field expects to receive an integer. Therefore, using the intval() function can solve your problem.
Indeed, I think your code returns an alphanumeric string.
Therefore, the code below will return 0 in all cases if no version is returned (not set, string or simply null):
$soft_instal->id_tipo_venta = intval($_POST['id_tipo_venta'][$key]);
On the other hand, intval() will always convert to int, so a decimal will be converted, example :
intval("1.1") // returns 1
intval("v1.1") // returns 0
If this is not the desired behavior, maybe you should think about changing your database type.
EDIT :
Of course, you can also set the value as null if you prefer to 0. You must allow nullable values in your database.
id_tipo_venta can not be empty, try with some number or change type column to varchar in the database
I have a object that I want to print it into string [key1=value1&key2=value2...etc] without the null value key value pair and comma into &.
So first of all i think of putting it into a map but it won't work and I don know how it work either.
val wxPayOrderObj = WxPayOrder(appid = "wx0b6dcsad20b379f1", mch_id =
"1508334851", nonce_str = UUID.randomUUID().toString(),sign = null,
body = "QQTopUp", out_trade_no = "20150806125346", total_fee = req.total_fee,
spbill_create_ip = "123.12.12.123",
trade_type = "JSAPI", openid = "oUpF8uMuAJO_M2pxb1Q9zNjWeS6o")
so the output will be
appid=wx0b6dc78d20b379f1&mch_id=150788851&nonce_str=UUID.randomUUID().toString()&
body=QQTopUp&out_trade_no=20150806125346&total_fee=req.total_fee&
spbill_create_ip=123.12.12.123&trade_type=JSAPI&openid=oUpF8uMuAJO_M2pxb1Q9zNjWeS6o
anyone please help me, thanks in advances.
I don't really get your question, but you want to convert object to string (to a format that you want)?
Override the object's toString() to return "[key1=value1&key2=value2...etc]"
example
override fun toString(){
// make sure you compute the data first
val answer = "[key1=$value1&key2=$value2...etc]"
return answer
}
The $ is used in string templates (That's directly writing the name of a variable, the value will be used later to be concatenated) with other strings)
I'm getting the following JSON response from the server:
{
"userId":"123456789",
"displayName":"display name"
}
When I use NSJSONSerialization.JSONObjectWithData and then prints the result NSDictionary I see in the console the following:
userId = 123456789
displayName = "display name"
Why do JSONObjectWithData changes the userId field type from String to a number?
It doesn't. The JSON deserialisation respects the data type and will maintain it. You can't tell the data type from a simple description log, you need to actually interrogate the class. The description log will quote some things if it makes more sense for the human reader, like spaces in the description, but it also omits quotes in some cases.
It doesn't.
Don't infer a variable type from its log representation, just test. Fire a Playground with this, for example:
let str = "{\"userId\":\"123456789\",\"displayName\":\"display name\"}"
if let data = str.dataUsingEncoding(NSUTF8StringEncoding),
jsonResult = try? NSJSONSerialization.JSONObjectWithData(data, options: []),
jsonObject = jsonResult as? [String:String],
id = jsonObject["userId"] {
print("User ID is " + id)
}
// goal: update Address record identified by "id", with new data in "colVal"
string cstr = ConnectionApi.GetSqlConnectionString("SwDb"); // get connection str
using (DataContext db = new DataContext(cstr)) {
Address addr = (from a in db.GetTable<Address>()
where a.Id == id
select a).Single<Address>();
addr.AddressLine1 = colValue.Trim();
db.SubmitChanges(); // this seems to have no effect!!!
}
In the debugger, addr has all the current values from the db table, and I can verify that AddressLine1 is changed just before I call db.SubmitChanges()... SQL Profiler shows only a "reset connection" when the SubmitChanges line executes. Anyone got a clue why this isn't working? THANKS!
You can get a quick view of the changes to be submitted using the GetChangeSet method.
Also make sure that your table has a primary key defined and that the mapping knows about this primary key. Otherwise you won't be able to perform updates.
Funny, to use GetTable and Single. I would have expected the code to look like this:
string cstr = ConnectionApi.GetSqlConnectionString("SwDb"); // get connection str
using (DataContext db = new DataContext(cstr))
{
Address addr = (from a in db.Address where a.Id == id select a).Single();
addr.AddressLine1 = colValue.Trim();
db.SubmitChanges(); // this seems to have no effect!!!
}
I got no idea what GetTable will do to you.
Another thing, for debugging Linq2SQL try adding
db.Log = Console.Out;
before SubmitChanges(), this will show you the executed SQL.
Thanks -- your comments will help me sort this out I'm sure! I didn't have the "Id" column defined as the PrimaryKey so that's an obvious non-starter. I would have expected that LinqToSQL would have thrown an error when the update fails. -- S.
Ok, here's the result. I can't use the form db.Address, because I didn't use the designer to create my database objects, instead I defined them as classes like this:
[Table(Name = "Addresses")]
public class Address
{
[Column(Name = "Id",IsPrimaryKey=true)]
public int Id { get; set; }
[Column(Name = "AddressLine1")]
public string AddressLine1 { get; set; }
...
Originally, I didn't have the "Id" column set as PK in the database, nor did I have it identified using IsPrimaryKey=true in the [Column...] specifier above. BOTH are required! Once I made that change, the ChangeSet found the update I wanted to do, and did it, but before that it told me that 0 rows needed to be updated and refused to commit the changes.
Thanks for your help! -- S.