PureBasic Requires Chilkat v11.7.0+

Get a PDF Field Value by its Label (Value to the Right)

See more PDF Text Extraction Examples

Demonstrates the "label" option, which captures the text that belongs to a caption such as "Invoice Number:" without needing coordinates. With labelValue "right", the value is the rest of the label's line. Label matching ignores case, extra spaces and a trailing colon. PureBasic

IncludeFile "CkPdf.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    success.i = 0

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

    ;  The invoice used in this example is available at invoice_labels.pdf

    pdf.i = CkPdf::ckCreate()
    If pdf.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPdf::ckLoadFile(pdf,"qa_data/pdf/invoice_labels.pdf")
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        ProcedureReturn
    EndIf

    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    jsonOut.i = CkJsonObject::ckCreate()
    If jsonOut.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  The invoice has lines such as "Invoice Number:   INV-2026-0412".
    ;  The label option restricts the "text" operation to the text belonging to the label.
    CkJsonObject::ckUpdateString(json,"label","Invoice Number")

    ;  "right" means the value is the rest of the label's line.
    ;  (The default, "auto", uses the rest of the line if there is text there, otherwise the block below.)
    CkJsonObject::ckUpdateString(json,"labelValue","right")

    success = CkPdf::ckExtractText(pdf,"text",json,jsonOut)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkJsonObject::ckDispose(jsonOut)
        ProcedureReturn
    EndIf

    ;  The value is returned as the text.
    Debug "Invoice Number: " + CkJsonObject::ckStringOf(jsonOut,"text")

    ;  The labelMatches array tells where the label was found and how it appeared in the PDF.
    Debug "Found on page " + Str(CkJsonObject::ckIntOf(jsonOut,"labelMatches[0].page")) + " as " + Chr(34) + CkJsonObject::ckStringOf(jsonOut,"labelMatches[0].label") + Chr(34)

    ;  Matching ignores case and the trailing colon, so these all work:
    CkJsonObject::ckUpdateString(json,"label","CUSTOMER:")
    success = CkPdf::ckExtractText(pdf,"text",json,jsonOut)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkJsonObject::ckDispose(jsonOut)
        ProcedureReturn
    EndIf

    Debug "Customer: " + CkJsonObject::ckStringOf(jsonOut,"text")

    CkJsonObject::ckUpdateString(json,"label","due date")
    success = CkPdf::ckExtractText(pdf,"text",json,jsonOut)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkJsonObject::ckDispose(jsonOut)
        ProcedureReturn
    EndIf

    Debug "Due Date: " + CkJsonObject::ckStringOf(jsonOut,"text")

    ;  The totals at the foot of the invoice are right-aligned labels with the amount beside them.
    CkJsonObject::ckUpdateString(json,"label","Total Due")
    success = CkPdf::ckExtractText(pdf,"text",json,jsonOut)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkJsonObject::ckDispose(jsonOut)
        ProcedureReturn
    EndIf

    Debug "Total Due: " + CkJsonObject::ckStringOf(jsonOut,"text")

    ;  A label that is not found is not an error.  The text is empty, labelMatches is empty,
    ;  and the quality report has an issue with the code "labelNotFound".
    CkJsonObject::ckUpdateString(json,"label","Tracking Number")
    success = CkPdf::ckExtractText(pdf,"text",json,jsonOut)
    If success = 0
        Debug CkPdf::ckLastErrorText(pdf)
        CkPdf::ckDispose(pdf)
        CkJsonObject::ckDispose(json)
        CkJsonObject::ckDispose(jsonOut)
        ProcedureReturn
    EndIf

    If CkJsonObject::ckSizeOfArray(jsonOut,"labelMatches") = 0
        Debug "Tracking Number: (not found) " + CkJsonObject::ckStringOf(jsonOut,"quality.pages[0].issues[0].code")
    EndIf

    ;  Sample output:

    ;  Invoice Number: INV-2026-0412
    ;  Found on page 1 as "Invoice Number:"
    ;  Customer: Northwind Traders
    ;  Due Date: April 13, 2026
    ;  Total Due: $1,234.53
    ;  Tracking Number: (not found) labelNotFound


    CkPdf::ckDispose(pdf)
    CkJsonObject::ckDispose(json)
    CkJsonObject::ckDispose(jsonOut)


    ProcedureReturn
EndProcedure