Can someone please clarify below issue.
Below validation throw NULL pointer error when pass null in myVar. It is because of !myVar.isEmpty()
if (myVar!= null || !myVar.isEmpty() ) {
some code///
}
Below works though as expected,
if (myVar!= null) {
if (!myVar.isEmpty()) {
some code///
}
Any other way of having both steps together.
If .isEmpty() is used on a string, then you can also just use Groovy
"truth" directly, as null and also empty strings are "false".
[null, "", "ok"].each{
if (it) {
println it
}
}
// -> ok
if ( myVar!= null && !myVar.isEmpty() ) {
//some code
}
the same as
if ( !( myVar== null || myVar.isEmpty() ) ) {
//some code
}
and to make it shorter - it's better to add method like hasValues
then check could be like this:
if( myVar?.hasValues() ){
//code
}
and finally to make it groovier - create a method boolean asBoolean()
class MyClass{
String s=""
boolean isEmpty(){
return s==null || s.length()==0
}
boolean asBoolean(){
return !isEmpty()
}
}
def myVar = new MyClass(s:"abc")
//in this case your check could be veeery short
//the following means myVar!=null && myVar.asBoolean()==true
if(myVar) {
//code
}
Related
When writing a sequence in an IYamlTypeConverter you might use some code like this:
public class MyObjectConverter : IYamlTypeConverter {
public MyObjectConverter() {}
public bool Accepts(Type type) { return typeof(IMyObject) == type || typeof(IMyObject[]) == type; }
public object ReadYaml(IParser parser, Type type) { return null; }
public void WriteYaml(IEmitter emitter, object value, Type type) {
var itemVal = value as IMyObject;
if (itemVal != null)
emitter.Emit(new Scalar(itemVal.GetID()));
else {
var arrayVal = value as IMyObject[];
emitter.Emit(new SequenceStart(null, null, true, SequenceStyle.Block));
if (arrayVal != null) {
foreach (var item in arrayVal)
if (item != null) emitter.Emit(new Scalar(item.GetID()));
else emitter.Emit(new Scalar("null"));
}
emitter.Emit(new SequenceEnd());
}
}
}
By calling emitter.Emit(new Scalar("null")) you would get a 'null' entry in the sequence, but if you leave the serialization up to YamlDotNet, it would be serialized as '' (empty string).
How do you output a null value in a sequence as an empty string when writing a custom IYamlTypeConverter?
One way to achieve this is to create a custom IEventEmitter that will add this logic:
public class NullStringsAsEmptyEventEmitter : ChainedEventEmitter
{
public NullStringsAsEmptyEventEmitter(IEventEmitter nextEmitter)
: base(nextEmitter)
{
}
public override void Emit(ScalarEventInfo eventInfo, IEmitter emitter)
{
if (eventInfo.Source.Type == typeof(string) && eventInfo.Source.Value == null)
{
emitter.Emit(new Scalar(string.Empty));
}
else
{
base.Emit(eventInfo, emitter);
}
}
}
You then register it like this:
var serializer = new SerializerBuilder()
.WithEventEmitter(nextEmitter => new NullStringsAsEmptyEventEmitter(nextEmitter))
.Build();
Here's a fiddle with this code
It seems you can represent a null value simply with '~', according to http://www.yaml.org/refcard.html
I get the following exception when trying to access a relationship document:
java.lang.ClassCastException: com.orientechnologies.orient.core.id.ORecordId cannot be cast to com.orientechnologies.orient.core.record.impl.ODocument
via:
Collection<ODocument> field = myDoc.field("MY_FIELD_NAME");
if(field != null) {
return field;
} else {
return Collections.emptySet();
}
The strange thing is that is happes not always, most of the time it works like expected.
Depending by what the field contains, you could use the interface OIdentifiable instead of ODocument.
Try using:
Collection<OIdentifiable> field = myDoc.field("MY_FIELD_NAME");
if(field != null) {
return field;
} else {
return Collections.emptySet();
}
MyHtmlHelper
public function url($url = null, $full = false) {
if(empty($url['lang']) && isset($this->params['lang'])) {
$url['lang'] = $this->params['lang'];
}
return parent::url($url, $full);
}
AppHelper
public function url($url = null, $full = false) {
if (empty($url['lang'])) {
$url['lang'] = $this->params['lang'];
}
return parent::url($url, $full);
}
when I ran . application warnings cakephp illegal offset lang .....
how do I fix that errors
Check the values you test are actually set first.
Change this:
if(empty($url['lang']) && isset($this->params['lang'])) {
$url['lang'] = $this->params['lang'];
}
To:
if ( ( ! isset( $url['lang'] ) || empty( $url['lang'] ) ) && isset( $this->params['lang'] ) ) {
$url['lang'] = $this->params['lang'];
}
I'm not sure whether I have this the right way round for what you're trying to achieve by the way. In my example I'm checking if the value of $url['lang'] is either not set or empty. It may be that you want to check that it is set and empty.
Use the same technique on the AppHelper as well to resolve your issue.
You need to add is_array($url) to your validation.
Or you might get “Illegal string offset ‘language'”
function url($url = null, $full = false) {
if(!isset($url['language']) && is_array($url) && isset($this->params['language']))
{
$url['language'] = $this->params['language'];
}
return parent::url($url, $full);
}
_bstr_t::wchar_t*, _bstr_t::char* operators return string of different types.
Do I need to delete or free them? using which function?
After stepping the implementation using debugger, my conclusion is that there is no need to manually delete/free the returned string. The lifetime of the returned string is managed by _bstr_t internally.
See the following snippets from the implementation:
// Extract a const char_t*
//
inline _bstr_t::operator const char*() const throw(_com_error)
{
return (m_Data != NULL) ? m_Data->GetString() : NULL;
}
inline const char* _bstr_t::Data_t::GetString() const throw(_com_error)
{
if (m_str == NULL) {
m_str = _com_util::ConvertBSTRToString(m_wstr);
if (m_str == NULL && m_wstr != NULL) {
_com_issue_error(E_OUTOFMEMORY);
}
}
return m_str;
}
inline void _bstr_t::Data_t::_Free() throw()
{
if (m_wstr != NULL) {
::SysFreeString(m_wstr);
}
if (m_str != NULL) {
delete [] m_str;
}
}
It is also okay to use unnamed _bstr_t as follows because _bstr_t instance is destroyed after the constructor of CString has finished.
CString abc((LPCTSTR)_bstr_t(OLESTR("ABC")));
AfxMessageBox(abc);
I have the following code which copies property values from one object to another objects by matching their property names:
public static void CopyProperties(object source, object target,bool caseSenstive=true)
{
PropertyInfo[] targetProperties = target.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);
PropertyInfo[] sourceProperties = source.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (PropertyInfo tp in targetProperties)
{
var sourceProperty = sourceProperties.FirstOrDefault(p => p.Name == tp.Name);
if (sourceProperty == null && !caseSenstive)
{
sourceProperty = sourceProperties.FirstOrDefault(p => p.Name.ToUpper() == tp.Name.ToUpper());
}
// If source doesn't have this property, go for next one.
if(sourceProperty ==null)
{
continue;
}
// If target property is not writable then we can not set it;
// If source property is not readable then cannot check it's value
if (!tp.CanWrite || !sourceProperty.CanRead)
{
continue;
}
MethodInfo mget = sourceProperty.GetGetMethod(false);
MethodInfo mset = tp.GetSetMethod(false);
// Get and set methods have to be public
if (mget == null)
{
continue;
}
if (mset == null)
{
continue;
}
var sourcevalue = sourceProperty.GetValue(source, null);
tp.SetValue(target, sourcevalue, null);
}
}
This is working well when the type of properties on target and source are the same. But when there is a need for casting, the code doesn't work.
For example, I have the following object:
class MyDateTime
{
public static implicit operator DateTime?(MyDateTime myDateTime)
{
return myDateTime.DateTime;
}
public static implicit operator DateTime(MyDateTime myDateTime)
{
if (myDateTime.DateTime.HasValue)
{
return myDateTime.DateTime.Value;
}
else
{
return System.DateTime.MinValue;
}
}
public static implicit operator MyDateTime(DateTime? dateTime)
{
return FromDateTime(dateTime);
}
public static implicit operator MyDateTime(DateTime dateTime)
{
return FromDateTime(dateTime);
}
}
If I do the following, the implicit cast is called and everything works well:
MyDateTime x= DateTime.Now;
But when I have a two objects that one of them has a DateTime and the other has MyDateTime, and I am using the above code to copy properties from one object to other, it doesn't and generate an error saying that DateTime can not converted to MyTimeDate.
How can I fix this problem?
One ghastly approach which should work is to mix dynamic and reflection:
private static T ConvertValue<T>(dynamic value)
{
return value; // This will perform conversion automatically
}
Then:
var sourceValue = sourceProperty.GetValue(source, null);
if (sourceProperty.PropertyType != tp.PropertyType)
{
var method = typeof(PropertyCopier).GetMethod("ConvertValue",
BindingFlags.Static | BindingFlags.NonPublic);
method = method.MakeGenericMethod(new[] { tp.PropertyType };
sourceValue = method.Invoke(null, new[] { sourceValue });
}
tp.SetValue(target, sourceValue, null);
We need to use reflection to invoke the generic method with the right type argument, but dynamic typing will use the right conversion operator for you.
Oh, and one final request: please don't include my name anywhere near this code, whether it's in comments, commit logs. Aargh.