I have this problem.
Im at the End of this Function:
FUNCTION ToString(Liste : Pokemon) : String;
VAR
RES : STRING;
BEGIN
ClrScr;
TextBackground(Green);
Writeln('DER POKEDEX:');
Writeln;
WHILE (Liste <> NIL) DO
BEGIN
RES := RES + Concat('#',IntToStr(Liste^.PkmnPos), ': ', Liste^.PkmnName, '. // ', IntToStr(Liste^.PkmnKG), ' kg', chr(13),chr(10),chr(13),chr(10));
Liste := Liste^.Next;
END;
TextBackground(Black);
ToString := Res;
END;
Now, I have the Procedure called "Submenu". So, when in the Main Program code, i can just call the procedure "Submenu()". But when im within this above functions, it wont compile my code. It says "identifier not found". But, after im done with this function the last thing it needs to do is go into submenu. And im really trying not to builed an infinite loop in wihtin the main program only to not have the programm end. What is the best way of doing that?
O, and I know, that if I have the function Submenu started before the other functions, it would work. But both functions call each other, so neither can be on top of each other because there will always be one, that wont work...
Regards.
Then you need a forward declaration:
FUNCTION ToString(Liste : Pokemon) : String; FORWARD;
FUNCTION Submenu();
BEGIN
..
ToString(Liste);
..
END;
FUNCTION ToString(Liste : Pokemon) : String;
BEGIN
// real implementation tostring
..
Submenu();
..
END;
Note the declaration with FORWARD
Related
What happened to the JSON deserializer of Delphi Sydney (10.4.1)?
After the migration from Delphi Seattle to Sydney, the standard marshal has problems with the deserialization of simple records.
Here is an example and simplified representation of my problem:
Data structure - Interation 1:
TAnalysisAdditionalData=record {order important for marshaling}
ExampleData0:Real; {00}
ExampleData1:Real; {01}
ExampleData2:String; {02}
end;
JSON representation:
"AnalysisAdditionalData":[0,1,"ExampleString"]
Data structure - Interation x, 5 years later:
TAnalysisAdditionalData=record {order important for marshaling}
ExampleData0:Real; {00}
ExampleData1:Real; {01}
ExampleData2:String; {02}
ExampleData3:String; {03} {since version 2016-01-01}
ExampleData4:String; {04} {since version 2018-01-01}
ExampleData5:String; {05}
end;
JSON representation:
"AnalysisAdditionalData":[0,1,"ExampleString0","ExampleString1","ExampleString2","ExampleString3"]
After interation 1, three string fields have been added.
If I now confront the standard marshal of Delphi Sydney (no custom converter, reverter, etc.) with an old dataset, so concretely with the data "AnalysisAdditionalData":[0,1, "ExampleString"], Sydney throws an EArgumentOutOfBoundsException because the 3 strings are expected - the deserialization fails.
Exit point is in Data.DBXJSONReflect in method TJSONUnMarshal.JSONToTValue - location marked below:
function TJSONUnMarshal.JSONToTValue(JsonValue: TJSONValue;
rttiType: TRttiType): TValue;
var
tvArray: array of TValue;
Value: string;
I: Integer;
elementType: TRttiType;
Data: TValue;
recField: TRTTIField;
attrRev: TJSONInterceptor;
jsonFieldVal: TJSONValue;
ClassType: TClass;
Instance: Pointer;
begin
// null or nil returns empty
if (JsonValue = nil) or (JsonValue is TJSONNull) then
Exit(TValue.Empty);
// for each JSON value type
if JsonValue is TJSONNumber then
// get data "as is"
Value := TJSONNumber(JsonValue).ToString
else if JsonValue is TJSONString then
Value := TJSONString(JsonValue).Value
else if JsonValue is TJSONTrue then
Exit(True)
else if JsonValue is TJSONFalse then
Exit(False)
else if JsonValue is TJSONObject then
// object...
Exit(CreateObject(TJSONObject(JsonValue)))
else
begin
case rttiType.TypeKind of
TTypeKind.tkDynArray, TTypeKind.tkArray:
begin
// array
SetLength(tvArray, TJSONArray(JsonValue).Count);
if rttiType is TRttiArrayType then
elementType := TRttiArrayType(rttiType).elementType
else
elementType := TRttiDynamicArrayType(rttiType).elementType;
for I := 0 to Length(tvArray) - 1 do
tvArray[I] := JSONToTValue(TJSONArray(JsonValue).Items[I],
elementType);
Exit(TValue.FromArray(rttiType.Handle, tvArray));
end;
TTypeKind.tkRecord, TTypeKind.tkMRecord:
begin
TValue.Make(nil, rttiType.Handle, Data);
// match the fields with the array elements
I := 0;
for recField in rttiType.GetFields do
begin
Instance := Data.GetReferenceToRawData;
jsonFieldVal := TJSONArray(JsonValue).Items[I]; <<<--- Exception here (EArgumentOutOfBoundsException)
// check for type reverter
ClassType := nil;
if recField.FieldType.IsInstance then
ClassType := recField.FieldType.AsInstance.MetaclassType;
if (ClassType <> nil) then
begin
if HasReverter(ClassType, FIELD_ANY) then
RevertType(recField, Instance,
Reverter(ClassType, FIELD_ANY),
jsonFieldVal)
else
begin
attrRev := FieldTypeReverter(recField.FieldType);
if attrRev = nil then
attrRev := FieldReverter(recField);
if attrRev <> nil then
try
RevertType(recField, Instance, attrRev, jsonFieldVal)
finally
attrRev.Free
end
else
recField.SetValue(Instance, JSONToTValue(jsonFieldVal,
recField.FieldType));
end
end
else
recField.SetValue(Instance, JSONToTValue(jsonFieldVal,
recField.FieldType));
Inc(I);
end;
Exit(Data);
end;
end;
end;
// transform value string into TValue based on type info
Exit(StringToTValue(Value, rttiType.Handle));
end;
Of course, this may make sense for people who, for example, only work with Sydney, or at least with Delphi versions above Seattle, or have started with these versions. I, on the other hand, have only recently been able to make the transition from Seattle to Sydney (Update 1).
Delphi Seattle has no problems with the missing record fields. Why should it, when they can be left untouched as default? Absurdly, however, Sydney has no problems with excess data.
Is this a known Delphi Sydney bug? Can we expect a fix? Or can the problem be worked around in some other way, i.e. compiler directive, Data.DBXJSONReflect.TCustomAttribute, etc.? Or, is it possible to write a converter/reverter for records? If so, is there a useful guide or resource that explains how to do this?
I, for my part, have unfortunately not found any useful information in this regard, only many very poorly documented class descriptions.
Addendum: Yes, it looks like it is a Delphi bug, and in my opinion a very dangerous one. Luckily, and I'm just about to deploy a major release, I discovered the bug while testing after porting to Sydney. But that was only by chance, because I had to deal with old datasets. I could have easily overlooked the flaw.
You should check if your projects are also affected. For me, the problem is a neckbreaker right now.
I have just written a very simple test program for the Embarcadero support team. If you want, you can have a look at it and test if your code is also affected.
Below are the instructions and the code:
Create a new project.
Creates two buttons and a memo on the main form.
Assign the two OnClick events for the buttons for load and save accordingly
Runs the program and clicks the save button.
Opens the .TXT in the application directory and delete e.g. the last entry of the record.
Click the load button and an EArgumentOutOfBoundsException is thrown.
unit main;
interface
uses
System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs,
FMX.Memo.Types, FMX.StdCtrls, FMX.Controls.Presentation, FMX.ScrollBox,
FMX.Memo;
type
TAnalysisAdditionalData=record {order important for marshaling}
ExampleData0:Real; {00}
ExampleData1:Real; {01}
ExampleData2:String; {02}
ExampleData3:String; {03} {since version 2016-01-01}
ExampleData4:String; {04} {since version 2018-01-01}
ExampleData5:String; {05}
end;
TSHCustomEntity=class(TPersistent)
private
protected
public
GUID:String;
end;
TSHAnalysis=class(TSHCustomEntity)
private
protected
public
AnalysisResult:String;
AnalysisAdditionalData:TAnalysisAdditionalData;
end;
TMainform = class(TForm)
Memo_Output: TMemo;
Button_Save: TButton;
Button_Load: TButton;
procedure Button_SaveClick(Sender: TObject);
procedure Button_LoadClick(Sender: TObject);
private
Analysis:TSHAnalysis;
procedure Marshal(Filename:String);
procedure Unmarshal(Filename:String);
function GetApplicationPath: String;
function GetFilename: String;
protected
procedure AfterConstruction;override;
public
Destructor Destroy;override;
property ApplicationPath:String read GetApplicationPath;
property Filename:String read GetFilename;
end;
var
Mainform: TMainform;
implementation
{$R *.fmx}
uses
DBXJSON,
DBXJSONReflect,
System.JSON;
{ TMainform }
procedure TMainform.AfterConstruction;
begin
inherited;
self.Analysis:=TSHAnalysis.Create;
self.Analysis.GUID:='6ed61388-cdd4-28dd-6efe-24461c4df3cd';
self.Analysis.AnalysisAdditionalData.ExampleData0:=0.5;
self.Analysis.AnalysisAdditionalData.ExampleData1:=0.9;
self.Analysis.AnalysisAdditionalData.ExampleData2:='ExampleString0';
self.Analysis.AnalysisAdditionalData.ExampleData3:='ExampleString1';
self.Analysis.AnalysisAdditionalData.ExampleData4:='ExampleString2';
self.Analysis.AnalysisAdditionalData.ExampleData5:='ExampleString3';
end;
destructor TMainform.Destroy;
begin
self.Analysis.free;
inherited;
end;
function TMainform.GetApplicationPath: String;
begin
RESULT:=IncludeTrailingPathDelimiter(ExtractFilePath(paramStr(0)));
end;
function TMainform.GetFilename: String;
begin
RESULT:=self.ApplicationPath+'6ed61388-cdd4-28dd-6efe-24461c4df3cd.txt';
end;
procedure TMainform.Button_SaveClick(Sender: TObject);
begin
self.Marshal(self.Filename);
end;
procedure TMainform.Button_LoadClick(Sender: TObject);
begin
if Analysis<>NIL then
FreeAndNil(Analysis);
self.Unmarshal(self.Filename);
self.Memo_Output.Text:=
self.Analysis.GUID+#13#10+
FloatToStr(self.Analysis.AnalysisAdditionalData.ExampleData0)+#13#10+
FloatToStr(self.Analysis.AnalysisAdditionalData.ExampleData1)+#13#10+
self.Analysis.AnalysisAdditionalData.ExampleData2+#13#10+
self.Analysis.AnalysisAdditionalData.ExampleData3+#13#10+
self.Analysis.AnalysisAdditionalData.ExampleData4+#13#10+
self.Analysis.AnalysisAdditionalData.ExampleData5;
end;
procedure TMainform.Marshal(Filename:String);
var
_Marshal:TJSONMarshal;
_Strings:TStringlist;
_Value:TJSONValue;
begin
_Strings:=TStringlist.Create;
try
_Marshal:=TJSONMarshal.Create;
try
_Value:=_Marshal.Marshal(Analysis);
_Strings.text:=_Value.ToString;
finally
if _Value<>NIL then
_Value.free;
_Marshal.free;
end;
_Strings.SaveToFile(Filename);
finally
_Strings.free;
end;
end;
procedure TMainform.Unmarshal(Filename:String);
var
_Strings:TStrings;
_UnMarshal:TJSONUnMarshal;
_Value:TJSONValue;
begin
if FileExists(Filename) then begin
_Strings:=TStringlist.create;
try
_Strings.LoadFromFile(Filename);
try
_Value:=TJSONObject.ParseJSONValue(_Strings.Text);
_UnMarshal:=TJSONUnMarshal.Create;
try
try
self.Analysis:=_UnMarshal.Unmarshal(_Value) as TSHAnalysis;
except
on e:Exception do
self.Memo_Output.text:=e.Message;
end;
finally
_UnMarshal.free;
end;
finally
if _Value<>NIL then
_Value.free;
end;
finally
_Strings.free;
end;
end;
end;
end.
To solve the problem temporarily, I have the following quick solution for you:
Make a copy of the standard library Data.DBXJSONReflect and name it e.g. Data.TempFix.DBXJSONReflect.
Change all includes/uses in your project accordingly.
After that navigate in Data.TempFix.DBXJSONReflect to line 2993:
jsonFieldVal := TJSONArray(JsonValue).Items[I];
And replace it with the following code:
try
jsonFieldVal := TJSONArray(JsonValue).Items[I];
except
on e:Exception do
if e is EArgumentOutOfRangeException then
continue
else
raise;
end;
After that the whole method should look like this:
function TJSONUnMarshal.JSONToTValue(JsonValue: TJSONValue; rttiType: TRttiType): TValue;
var
tvArray: array of TValue;
Value: string;
I: Integer;
elementType: TRttiType;
Data: TValue;
recField: TRTTIField;
attrRev: TJSONInterceptor;
jsonFieldVal: TJSONValue;
ClassType: TClass;
Instance: Pointer;
begin
// null or nil returns empty
if (JsonValue = nil) or (JsonValue is TJSONNull) then
Exit(TValue.Empty);
// for each JSON value type
if JsonValue is TJSONNumber then
// get data "as is"
Value := TJSONNumber(JsonValue).ToString
else if JsonValue is TJSONString then
Value := TJSONString(JsonValue).Value
else if JsonValue is TJSONTrue then
Exit(True)
else if JsonValue is TJSONFalse then
Exit(False)
else if JsonValue is TJSONObject then
// object...
Exit(CreateObject(TJSONObject(JsonValue)))
else
begin
case rttiType.TypeKind of
TTypeKind.tkDynArray, TTypeKind.tkArray:
begin
// array
SetLength(tvArray, TJSONArray(JsonValue).Count);
if rttiType is TRttiArrayType then
elementType := TRttiArrayType(rttiType).elementType
else
elementType := TRttiDynamicArrayType(rttiType).elementType;
for I := 0 to Length(tvArray) - 1 do
tvArray[I] := JSONToTValue(TJSONArray(JsonValue).Items[I],
elementType);
Exit(TValue.FromArray(rttiType.Handle, tvArray));
end;
TTypeKind.tkRecord, TTypeKind.tkMRecord:
begin
TValue.Make(nil, rttiType.Handle, Data);
// match the fields with the array elements
I := 0;
for recField in rttiType.GetFields do
begin
Instance := Data.GetReferenceToRawData;
try
jsonFieldVal := TJSONArray(JsonValue).Items[I];
except
on e:Exception do
if e is EArgumentOutOfRangeException then
continue
else
raise;
end;
// check for type reverter
ClassType := nil;
if recField.FieldType.IsInstance then
ClassType := recField.FieldType.AsInstance.MetaclassType;
if (ClassType <> nil) then
begin
if HasReverter(ClassType, FIELD_ANY) then
RevertType(recField, Instance,
Reverter(ClassType, FIELD_ANY),
jsonFieldVal)
else
begin
attrRev := FieldTypeReverter(recField.FieldType);
if attrRev = nil then
attrRev := FieldReverter(recField);
if attrRev <> nil then
try
RevertType(recField, Instance, attrRev, jsonFieldVal)
finally
attrRev.Free
end
else
recField.SetValue(Instance, JSONToTValue(jsonFieldVal,
recField.FieldType));
end
end
else
recField.SetValue(Instance, JSONToTValue(jsonFieldVal,
recField.FieldType));
Inc(I);
end;
Exit(Data);
end;
end;
end;
// transform value string into TValue based on type info
Exit(StringToTValue(Value, rttiType.Handle));
end;
I have a code that changes a value of a determinated pair in a existent JSON file and works perfectly. Now i need add one object and one pair to this file, using great part this same code. So how do this?
Thank you.
uses
System.Json, ShFolder, System.IOUtils;
...
function GetSpecialFolderPath(folder : integer) : string;
const
SHGFP_TYPE_CURRENT = 0;
var
path: array [0..MAX_PATH] of char;
begin
if SUCCEEDED(SHGetFolderPath(0,folder,0,SHGFP_TYPE_CURRENT,#path[0])) then
Result := path
else
Result := '';
end;
procedure ChangeChromeSetting(const ATarget, Avalue: string);
var
specialfolder: integer;
caminhochrome: String;
JSONObj, Obj: TJSONObject;
JSONPair: TJSONPair;
OldValue: string;
begin
specialFolder := CSIDL_LOCAL_APPDATA;
caminhochrome := GetSpecialFolderPath(specialFolder);
caminhochrome := caminhochrome + '\Google\Chrome\User Data\Local State';
if fileexists(caminhochrome) then
begin
Obj := TJSONObject.Create;
JSONObj := TJSONObject.ParseJSONValue(TFile.ReadAllText(caminhochrome)) as TJSONObject;
if not Assigned(JSONObj) then raise Exception.Create('Cannot read file: ' + caminhochrome);
try
OldValue := JSONObj.GetValue<string>(ATarget);
if not SameText(OldValue, Avalue) then
begin
JSONPair := JSONObj.Get(ATarget);
JSONPair.JsonValue.Free;
JSONPair.JsonValue := TJSONString.Create(Avalue);
///////////////////////////////////////////////////
Obj.AddPair('enabled', TJSONBool.Create(false)); // Trying add pair
JSONObj.AddPair('hardware_acceleration_mode', Obj); // Trying add object
//////////////////////////////////////////////////
TFile.WriteAllText(caminhochrome, JSONObj.ToJSON); // Don't add object and pair
end;
finally
JSONObj.Free;
end;
end;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
ChangeChromeSetting('hardware_acceleration_mode_previous', 'false');
end;
This is result that i'm waiting
"hardware_acceleration_mode":{"enabled":false}
Your code is somewhat confusing since you pass in some of the names as arguments, but then hard code others inside the function. Abstracting functionality is good practise but before you can abstract you really need to ensure the code works correctly. I'm going to show code that does not attempt to be abstract. Once you are satisfied it behaves as you need, then feel free to abstract away.
This code does what I believe is your intent:
var
root: TJSONObject;
value: TJSONObject;
prev: string;
begin
root := TJSONObject.ParseJSONValue(TFile.ReadAllText(FileName)) as TJSONObject;
try
prev := root.GetValue<string>('hardware_acceleration_mode_previous');
if not SameText(prev, 'false') then
begin
// remove existing value, if it exists
root.RemovePair('hardware_acceleration_mode').Free;
// create a new object, and initialise it
value := TJSONObject.Create;
value.AddPair('enabled', 'false');
// add the object at the root level
root.AddPair('hardware_acceleration_mode', value);
// save to file
TFile.WriteAllText(FileName, root.ToJSON);
end;
finally
root.Free;
end;
end;
Note that I have ensured that there are no memory leaks. I've used RemovePair to make sure that if there is an existing value named hardware_acceleration_mode it is first removed.
What is the cause of (apparently) spurious warnings when compiling local functions of anonymous functions, and how do I eliminate them.
A simple function compiles clean - no warnings. If the function is a local function of another function, again there are no warnings. If the function is a local function of an anonymous function it gives rise to the following warnings:
[DCC Warning] Unit1.pas(57): W1036 Variable 'i' might not have been initialized
[DCC Warning] Unit1.pas(58): W1035 Return value of function 'StrToJType' might be undefined
Example code is set out below. Please note that though this code compiles, it gives warnings unrelated to this question because it is incomplete.
EDIT
Comments and responses suggest that the fact that the example code contains no return value in the anonymous function may be the cause of the problem. This edit amends the code to remedy this, to simplify the local function case, and to minimise the code. The problem is still the same.
unit Unit1;
interface
type
JType = (JAtLeastOnce, JConditionLine, JInfix, JIteration, JNonNullInfix );
TFuncTest = reference to function : JType;
function StrToJType(aString : string) : JType;
implementation
function StrToJType(aString : string) : JType;
// Basic function - does not give warnings
var
i : integer;
begin
i := Pos(aString, '+i*-?');
if i <> 0 then result := JType(i - 1) else result := High(JType);
end;
function Test : JType;
// Local function - does not give warnings
function StrToJType(aString : string) : JType;
var
i : integer;
begin
i := Pos(aString, '+i*-?');
if i <> 0 then result := JType(i - 1) else result := High(JType);
end;
begin
result := low(JType);
end;
function Test2 : TFuncTest;
// Local function of anonymous function - gives warnings
begin
result :=
function : JType
function StrToJType(aString : string) : JType;
var
i : integer;
begin
i := Pos(aString, '+i*-?');
if i <> 0 then result := JType(i - 1) else result := High(JType);
end;
begin
result := Low(JType);
end;
end;
end.
Your anonymous function does not assign its return value.
function Test2 : TFuncTest;
// Local function of anonymous function - gives warnings
begin
result :=
function : JStructureType
function StrToJType(aString : string) : JStructureType;
const
c : string = '+i*-?p!qoxsc<^>8|';
var
i : integer;
begin
i := Pos(aString, c);
if (aString <> '') and (i <> 0) then result := JStructureType(i - 1)
else result := High(JStructureType);
end;
begin
// need to return something here
end;
end;
The compiler should also object to you making the same mistake in Test.
If the compiler really is complaining about StrToJType after you've fixed all the other errors, that would be a compiler bug and should be submitted to Quality Portal.
Update
Your edit confirms that the warnings in the local function remain when you resolve the other mistakes. So this would appear to be a compiler bug. Please make a minimal reproduction and submit it.
Of course Delphi XE won't be updated in the future. Unless this bug still exists in XE8 there's probably no point in reporting a bug.
One might suspect that the compiler is confused by a local function, local to an anonymous method, that is never called
I'm trying to catch the following JSON array :
[{"name":"Bryan","email":"Bryan#hotmail.com"},
{"name":"Louis","email":"Louis#hotmail.com"},
{"name":"Maria","email":"Maria#hotmail.com"},
{"name":"Test","email":"test#hotmail.com"},
{"name":"Anthony","email":"anthony#hotmail.com"}]
and put it in Memo or ListBox in Delphi :
the code is the following :
procedure TForm1.Button1Click(Sender: TObject);
var jv: TJSONValue;
jo: TJSONObject;
jp: TJSONPair;
ja: TJSONArray;
i: integer;
j: integer;
begin
RESTRequest1.Execute;
jv:=RESTResponse1.JSONValue;
jo:= TJSONObject.ParseJSONValue(jv.ToString) as TJSONObject;
try
for i := 0 to jo.Size - 1 do
begin
jp := jo.Get(i);
if jp.JsonValue is TJSONArray then
begin
ja := jp.JsonValue as TJSONArray;
for j := 0 to ja.Size -1 do
Memo1.Lines.Add(ja.Get(i).ClassName + ': ' + ja.Get(j).ToString);
end
else
Memo1.Lines.Add(jp.ClassName + ': '+ jp.ToString);
end;
finally
jo.Free;
end;
end;
When I click in Button I got the following error message :
Invalid class typecast
during debugging the following line has a problem :
jo:= TJSONObject.ParseJSONValue(jv.ToString) as TJSONObject;
I don't know how to resolve this problem or this mistake ,
Could you please help me ?
Thanks.
This could perfectly well be worked out by reading the code and looking at the JSON. However, I'd like to show you how to go about debugging such a problem in case you cannot work it out by static analysis. When an as cast fails that is always because the object on the left hand side of the as does not derive from the type on the right hand side. The next step then is always to inquire as to what the type of the object on the left hand side is. I've included a short MCVE above as a means to demonstrate.
The output of this program:
{$APPTYPE CONSOLE}
uses
System.JSON;
const
JSON = '[{"name":"Bryan","email":"Bryan#hotmail.com"},' +
' {"name":"Louis","email":"Louis#hotmail.com"},' +
' {"name":"Maria","email":"Maria#hotmail.com"},' +
' {"name":"Test","email":"test#hotmail.com"},' +
' {"name":"Anthony","email":"anthony#hotmail.com"}]';
begin
Writeln(TJSONObject.ParseJSONValue(JSON).ClassName);
end.
is
TJSONArray
Now, TJSONArray does not derive from TJSONObject. Hence your as cast raise a runtime error. If you cast the value returned by ParseJSONValue to TJSONArray that will succeed.
This is to be expected since the root of your JSON is an array and is not an object.
You need to modify your code so that it does not assume that the root level is always an object. You need different behaviour for arrays and objects.
I'm not sure what the problem of TJSONObject is with the string you posted.
For some reason it will parse it if you changed it.
{"Persons":[{"name":"Bryan","email":"Bryan#hotmail.com"},{"name":"Louis","email":"Louis#hotmail.com"},{"name":"Maria","email":"Maria#hotmail.com"},{"name":"Test","email":"test#hotmail.com"},{"name":"Anthony","email":"anthony#hotmail.com"}]}
If I run the code as it is I get the following result
If you don't mind using something different than default Delphi units I would suggest superobject (Link here)
superobject will parse your JSON edited and as posted.
Your code would look like this:
Const
MyJSON = '[{"name":"Bryan","email":"Bryan#hotmail.com"},{"name":"Louis","email":"Louis#hotmail.com"},{"name":"Maria","email":"Maria#hotmail.com"},{"name":"Test","email":"test#hotmail.com"},{"name":"Anthony","email":"anthony#hotmail.com"}]';
procedure ParseJSON;
var
obj: ISuperObject;
Ar: TSuperArray;
I: integer;
begin
obj := SO(MyJSON);
if obj.IsType(stArray) then
begin
Ar := obj.AsArray;
try
for I := 0 to Ar.Length-1 do
L.Add(Ar.O[I].AsString);
finally
Ar.Free;
end;
end
else
L.Add(Obj.AsString);
end;
Result:
For Koul, to get the element names and values.
Like I said not very pretty code but ok.
Ar.O[0].AsObject.GetNames.AsArray.S[0]
To cut it up in pieces a bit.
Ar.O[0] //Get the first element in the array as ISuperObject
.AsObject //Get it as TSuperTableString
.GetNames //Gets all names in the array, in this case "name" and "email"
.AsArray[0]//Get the first name in the names array.
It will result in email (Names are sorted A-Z)
You can do the same for the values by calling GetValues instead of GetNames.
I think the prettiest way to get it will be defining 2x more TSuperArray
procedure PrintNamesAndValues;
Var
Ar, ArNames, ArValues:TSuperArray;
I: Integer;
begin
Ar := SO(<JSON string>).asArray;
ArNames := Ar.O[0].AsObject.GetNames.AsArray;
ArValues := Ar.O[0].AsObject.GetValues.AsArray;
For I := 0 to ArNames.Length-1 do
WriteLn(Format('%s: %s',[ArNames.S[I], ArValues.S[I]]));
end;
Hope it's all clear enough :)
When using TJson.JsonToObject in a multi-thread environment random access violations occur. I was searching a long time for the problem and I could isolate it with the following code
JSON class
type
TParameter = class
public
FName : string;
FDataType : string;
FValue : string;
end;
Testfunction:
procedure Test();
var
myTasks: array of ITask;
i : integer;
max : integer;
begin
max := 50;
SetLength(myTasks, max);
for i := 0 to max -1 do begin
myTasks[i] := TTask.Create(procedure ()
var
json : string;
p : TParameter;
begin
json := '{"name":"NameOfParam","dataType":"TypeOfParam","value":"ValueOfParam"}';
p := TJson.JsonToObject<TParameter>(json);
p.Free;
end);
myTasks[i].Start;
end;
TTask.WaitForAll(myTasks);
ShowMessage('all done!');
end;
It's only a code snippet based of a much more complex source. As long I use this code in a single thread everything works without a problem. I'm wondering if there is anything wrong with the code.
The method TJSONUnMarshal.ObjectInstance in REST.JsonReflect.pas has a severe bug:
It calls FreeAndNil on a TRttiType instance. This should never be done because all TRtti*** instances are managed by the TRttiContext.
After I removed the FreeAndNil call I could not reproduce the access violation anymore.
Reported as: https://quality.embarcadero.com/browse/RSP-10035
P.S. I also think that https://quality.embarcadero.com/browse/RSP-9815 will affect your code.