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| unit jsonadapter;
interface
uses
System.SysUtils,
System.Classes,
System.Json,
Data.DB;
type
EDataTypeCoersion = class(Exception); //- Can't alter data-type for existing field definition.
EDataTypeUnsupported = class(Exception); //- Can't support data-type from json data. (objects and arrays)
EUnknownDataType = class(Exception); //- Unable to determine data type from json data.
type
TJSONDatasetAdapter = class(TComponent)
private
fJSON: TStrings;
fDatasetRef: TDataset;
procedure SetDatasetRef(const Value: TDataset);
procedure setJSON(const Value: TStrings);
procedure SetFieldDefs(a: TJSONArray);
procedure InsertData(a: TJSONArray);
public
constructor Create( aOwner: TComponent ); override;
destructor Destroy; override;
public
procedure UpdateDataset;
published
property JSON: TStrings read fJSON write setJSON;
property Dataset: TDataset read fDatasetRef write SetDatasetRef;
end;
procedure Register;
implementation
procedure Register;
begin
RegisterComponents('REST Client', [TJSONDatasetAdapter]);
end;
{ TJSONDatasetAdapter }
constructor TJSONDatasetAdapter.Create(aOwner: TComponent);
begin
inherited Create( aOwner );
fJSON := TStringList.Create;
fJSON.Text := '[]';
fDatasetRef := nil;
end;
destructor TJSONDatasetAdapter.Destroy;
begin
fJSON.DisposeOf;
fDatasetRef := nil;
inherited Destroy;
end;
procedure TJSONDatasetAdapter.SetDatasetRef(const Value: TDataset);
begin
fDatasetRef := Value;
UpdateDataset;
end;
procedure TJSONDatasetAdapter.setJSON(const Value: TStrings);
begin
if not assigned(value) then begin
fJSON.Clear;
exit;
end;
fJSON.Assign(Value);
UpdateDataset;
end;
procedure TJSONDatasetAdapter.SetFieldDefs( a: TJSONArray );
var
o: TJSONObject;
e: TJSONPairEnumerator;
p: TJSONPair;
v: TJSONValue;
n: string;
idx: uint32;
FieldDef: TFieldDef;
begin
if a.Count<1 then begin
exit;
end;
//- Loop through data to determine data-types.
for idx := 0 to pred(a.Count) do begin
v := a.Items[idx];
if not (v is TJSONObject) then begin
exit;
end;
o := v as TJSONObject;
try
e := o.GetEnumerator;
if not e.MoveNext then begin
exit;
end;
repeat
p := e.GetCurrent;
if not assigned(p) then continue;
//- Get the name of the field, and ensure we have a field def.
n := Lowercase(Trim(p.JsonString.ToString));
n := StringReplace(n,'"','',[rfReplaceAll]);
FieldDef := nil;
if fDatasetRef.FieldDefs.IndexOf(n)>=0 then begin
FieldDef := fDatasetRef.FieldDefs.Find(n);
end;
if not assigned(FieldDef) then begin
FieldDef := fDatasetRef.FieldDefs.AddFieldDef;
FieldDef.Name := n;
end;
//- Determine the type of field.
v := p.JsonValue;
if v is TJSONString then begin
if (FieldDef.DataType=TFieldType.ftUnknown) then begin
FieldDef.DataType := TFieldType.ftString;
end;
end else if v is TJSONNumber then begin
if (FieldDef.DataType=TFieldType.ftUnknown) then begin
FieldDef.DataType := TFieldType.ftFloat;
end else if (FieldDef.DataType <> TFieldType.ftFloat) then begin
raise EDataTypeCoersion.Create('');
end;
end else if v is TJSONBool then begin
if (FieldDef.DataType=TFieldType.ftUnknown) then begin
FieldDef.DataType := TFieldType.ftBoolean;
end else if (FieldDef.DataType<>ftBoolean) then begin
raise EDataTypeCoersion.Create('');
end;
end else if v is TJSONNull then begin
//- Do nothing, another record may indicate data type.
end else if v is TJSONObject then begin
raise EDataTypeUnsupported.Create('');
end else if v is TJSONArray then begin
raise EDataTypeUnsupported.Create('');
end;
until not e.MoveNext;
finally
o := nil;
end;
end;
//- Ensure that all field defs have known data types.
if fDatasetRef.FieldDefs.Count<1 then begin
exit;
end;
for idx := 0 to pred(fDatasetRef.FieldDefs.Count) do begin
if fDatasetRef.FieldDefs[idx].DataType=TFieldType.ftUnknown then begin
raise EUnknownDataType.Create('field: '+fDatasetRef.FieldDefs[idx].Name);
end;
end;
end;
procedure TJSONDatasetAdapter.InsertData( a: TJSONArray );
var
idx: uint32;
idy: uint32;
v: TJSONValue;
o: TJSONObject;
FieldName: string;
begin
if fDatasetRef.FieldDefs.Count<1 then begin
exit;
end;
if a.Count<1 then begin
exit;
end;
for idx := 0 to pred(a.Count) do begin
v := a.Items[idx];
if not (v is TJSONObject) then continue; //[ Exception here? ]
o := v as TJSONObject;
fDatasetRef.Insert;
for idy := 0 to pred(fDatasetRef.FieldDefs.Count) do begin
FieldName := fDatasetRef.FieldDefs[idy].Name;
v := o.GetValue(FieldName);
if assigned(v) then begin
if v is TJSONString then begin
fDatasetRef.FieldByName(FieldName).AsString := TJSONString(v).Value;
end else begin
fDatasetRef.FieldByName(FieldName).AsString := v.ToJSON;
end;
end;
end;
fDatasetRef.Post;
end;
end;
procedure TJSONDatasetAdapter.UpdateDataset;
var
o: TJSONObject;
a: TJSONArray;
v: TJSONValue;
begin
if not assigned(fDatasetRef) then begin
exit;
end;
fDatasetRef.Active := False;
fDatasetRef.FieldDefs.Clear;
try
// o := TJSONObject.ParseJSONValue(TEncoding.ASCII.GetBytes('{ "data": '+fJSON.Text+'}'),0) as TJSONObject;
o := TJSONObject.ParseJSONValue(TEncoding.UTF8.GetBytes('{ "data": '+fJSON.Text+'}'),0) as TJSONObject; // à tester
except
on E: Exception do begin
exit;
end;
end;
if not assigned(o) then begin
exit;
end;
v := o.GetValue('data');
if not assigned(v) then begin
exit;
end;
if not (v is TJSONArray) then begin
exit;
end;
a := v as TJSONArray;
if a.Count=0 then begin
exit;
end;
SetFieldDefs(a);
fDatasetRef.Active := True;
InsertData(a);
end;
end. |
Récupérer un tableau d'une API via REST Client et ClientDataSet
Répondre avec citation
et comment ça marche si plusieurs tableaux dans le paramètre retour !?!!
Envoyé par delaio
). 
un grand merci pour tes recherches... mes dev pour cette appli sont déjà terminés sur la partie traitement JSON mais j'ai hâte de pouvoir tester ta découverte dans un prochain projet...
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