Go PDF template: can't evaluate field X in type struct-CodePudding

My question might be looks similar from existing question but it's totally different. Please read it in details.

So, I'm trying to generate 2 different PDF based on specific condition. Let's say, if condition A then the PDF has stamp, else it's not.

I have 2 struct which is:

//no stamp
    templateData := struct {
        Name                string
    }{
        Data:               data,
        DataDetails:        dataDetailsPDF,
        Name:               name,
    }

//with stamp
    templateDataStamp := struct {
        Name                string
                StampLink:          string
    }{
        Data:               data,
        DataDetails:        dataDetailsPDF,
        Name:               name,
                StampLink:          config.PDF.StampImageLink,
    }

Based on those 2 struct, I have if condition like this:

pdfRequest := pdf.NewRequestPDF(config, "Body.html", "Header.html", "Footer.html")

    if data.Valid == "1" {
        err = pdfRequest.ParseTemplate(templateDataStamp)
        if err != nil {
            return nil, helper.Error(codes.Internal, tracestr, err)
        }
    } else {
        err = pdfRequest.ParseTemplate(templateData)
        if err != nil {
            return nil, helper.Error(codes.Internal, tracestr, err)
        }
    }

It works well till I'm trying to generate PDF without stamp (the else condition), it shows an error like this

can't evaluate field StampLink in type struct{
        Name                string
    }

Below is my html template that contains StampLink:

<img src="{{.StampLink}}" width="150px" alt="">

Is there any solution to fix the error if the {{.StampLink}} on html template is empty?

I'm sorry if it is too long, but I want to explain as much detail as possible, thank you.

CodePudding user response：

You are using same template therefore passing struct without StampLink causes error.

Use struct with all field and conditions to render it if not empty.

From docs

{{if pipeline}} T1 {{end}}
If the value of the pipeline is empty, no output is generated; otherwise, T1 is executed. The empty values are false, 0, any nil pointer or interface value, and any array, slice, map, or string of length zero. Dot is unaffected.

{{ if .StampLink }} <img src="{{.StampLink}}" width="150px" alt=""> {{ end }}