Go Requires Chilkat v11.7.0+

Get Every Occurrence of a Label in a PDF

See more PDF Text Extraction Examples

Demonstrates the "labelOccurrence" option. When the same label appears more than once (for example "Total:" on each of several receipts), "first" (the default) uses the first occurrence, "all" returns every occurrence with its page, and a number selects one occurrence. Go

    success := false

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    //  The PDF used in this example (three receipts, one per page) is available at three_receipts.pdf

    pdf := chilkat.NewPdf()
    success = pdf.LoadFile("qa_data/pdf/three_receipts.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        return
    }

    json := chilkat.NewJsonObject()
    jsonOut := chilkat.NewJsonObject()

    //  Each of the three pages is a receipt with a "Total:" line.
    json.UpdateString("label","Total")
    json.UpdateString("labelValue","right")

    //  By default only the first occurrence (in reading order) is used.
    success = pdf.ExtractText("text",json,jsonOut)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        return
    }

    fmt.Println("First total: ", *jsonOut.StringOf("text"))

    //  labelOccurrence "all" returns every occurrence.  The "text" member holds the values joined
    //  by line breaks, and labelMatches has one entry per occurrence with its page.
    json.UpdateString("labelOccurrence","all")
    success = pdf.ExtractText("text",json,jsonOut)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        return
    }

    i := 0
    count_i := jsonOut.SizeOfArray("labelMatches")
    for i < count_i {
        jsonOut.SetI(i)
        fmt.Println("Page ", jsonOut.IntOf("labelMatches[i].page"), " total: ", *jsonOut.StringOf("labelMatches[i].text"))
        i = i + 1
    }

    //  A number selects one occurrence: 2 is the second.
    json.UpdateInt("labelOccurrence",2)
    success = pdf.ExtractText("text",json,jsonOut)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        return
    }

    fmt.Println("Second total: ", *jsonOut.StringOf("text"))

    //  The occurrences are counted over the selected pages, so combining "pages" with the label
    //  is another way to pick one receipt:
    json.UpdateString("labelOccurrence","first")
    json.UpdateString("pages","3")
    json.UpdateString("label","Receipt No.")
    success = pdf.ExtractText("text",json,jsonOut)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jsonOut.DisposeJsonObject()
        return
    }

    fmt.Println("Receipt number on page 3: ", *jsonOut.StringOf("text"))

    //  Sample output:

    //  First total: $19.86
    //  Page 1 total: $19.86
    //  Page 2 total: $17.34
    //  Page 3 total: $23.62
    //  Second total: $17.34
    //  Receipt number on page 3: 1003

    pdf.DisposePdf()
    json.DisposeJsonObject()
    jsonOut.DisposeJsonObject()