IJsonDocument.ReadFromFile

Syntax

ReadFromFile(FileName: String);

Parameters

FileName. JSON file path and name.

Description

The ReadFromFile method loads JSON structure from the specified file.

Example

Executing the example requires the JSON file: d:\Work\Json\testfile.json.

Sub UserProc;
Var
    Doc: IJsonDocument;
    JSON: IJsonObject;
Begin
    Doc := New JsonDocument.Create;
    Doc.ReadFromFile("d:\Work\Json\testfile.json");
    JSON := Doc.RootElement.AsObject;
    ShowElements(JSON);
End Sub UserProc;

Sub ShowElements(JSON: IJsonObject);
Var
    Element: IJsonElement;
    i, c: Integer;
Begin
    c := JSON.Count;
    For i := 0 To c - 1 Do
        Element := JSON.ItemByIndex(i);
        Debug.WriteLine("Name: " + JSON.Property_(i));
        Debug.Write("Type: " + Element.GetType.ToString + ". Value: ");
        ShowElement(Element);
    End For;
End Sub ShowElements;

Sub ShowElement(Element: IJsonElement);
Begin
    Select Case Element.GetType
        Case JsonElementType.Boolean: Debug.WriteLine(Element.AsBoolean);
        Case JsonElementType.Double: Debug.WriteLine(Element.AsDouble);
        Case JsonElementType.Integer: Debug.WriteLine(Element.AsInteger);
        Case JsonElementType.NullValue: Debug.WriteLine("null value");
        Case JsonElementType.String: Debug.WriteLine(Element.AsString);
        Case JsonElementType.Array: ShowArray(Element.AsArray);
        Case JsonElementType.Object: ShowElements(Element.AsObject);
    End Select;
End Sub ShowElement;

Sub ShowArray(JSONArray: IJsonArray);
Var
    Element: IJsonElement;
    i, c: Integer;
Begin
    Debug.Indent;
    c := JSONArray.Count;
    Debug.WriteLine("Number of selected elements: " + c.ToString);
    For i := 0 To c - 1 Do
        Element := JSONArray.Item(i);
        ShowElement(Element);
    End For;
    Debug.Unindent;
End Sub ShowArray;

After executing the example, the JSON structure will be read from the file. Information about single structure elements will be displayed in the development environment console.