always consider empty strings as no value given

components/App.tsx

@@ -11,10 +11,23 @@ import { IDocProps } from '../interfaces/IDocProps'
 
 export default function App() {
   const [options, setOptions] = useState<IDocProps>({
+    address: 'Max Mustermann\\\\Musterstrasse\\\\12345 Musterstadt',
+    body: 'Inhalt des Briefs',
+    closing: 'Mit freundlichen Grüßen',
+    customer: '',
+    date: new Date().toLocaleDateString('de-DE'),
+    enclosing: '',
+    invoice: '',
+    myRef: '',
+    opening: 'Sehr geehrte Damen und Herren',
+    ps: '',
+    signature: '',
+    specialMail: '',
+    subject: 'Betreffzeile',
     template: 'brief-fam',
-    subject: '',
-    body: '',
-    address: '',
+    yourMail: '',
+    yourRef: '',
+    yourRefName: '',
   })
   const [latest, setLatest] = useState<ILatest[]>([])
   const [pdfUrl, setPdfUrl] = useState<string | null>(null)
@@ -32,7 +45,7 @@ export default function App() {
       return
     }
     const value = event && event.target && event.target.value
-    setOptions({ ...options, [name]: value || undefined })
+    setOptions({ ...options, [name]: value })
   }
 
   const _onSelectLatest = (selectedOption: ILatest) => {

interfaces/IDocProps.ts

@@ -1,15 +1,19 @@
 export interface IDocProps {
-  template: string
-  subject: string
-  body: string
   address: string
-  date?: string
-  opening?: string
-  closing?: string
-  yourRef?: string
-  yourMail?: string
-  myRef?: string
-  customer?: string
-  invoice?: string
-  specialMail?: string
+  body: string
+  closing: string
+  customer: string
+  date: string
+  enclosing: string
+  invoice: string
+  myRef: string
+  opening: string
+  ps: string
+  signature: string
+  specialMail: string
+  subject: string
+  template: string
+  yourMail: string
+  yourRef: string
+  yourRefName: string
 }

lib/templates.ts

@@ -6,23 +6,23 @@ function convertLineBreaks(lines: string) {
 
 export function brief(options: IDocProps) {
   const {
-    template = 'brief-fam',
-    subject = '',
-    yourRef = '',
-    yourRefName = 'Ihr Zeichen',
-    yourMail = '',
-    myRef = '',
-    customer = '',
-    invoice = '',
-    date = '\\today',
-    signature = '',
-    specialMail = '',
-    address = 'Max Mustermann\\\\Musterstrasse\\\\12345 Musterstadt',
-    opening = 'Sehr geehrte Damen und Herren',
-    body = '',
-    closing = 'Mit freundlichen Grüßen',
-    ps = '',
-    enclosing = '',
+    template,
+    subject,
+    yourRef,
+    yourRefName,
+    yourMail,
+    myRef,
+    customer,
+    invoice,
+    date,
+    signature,
+    specialMail,
+    address,
+    opening,
+    body,
+    closing,
+    ps,
+    enclosing,
   } = { ...options }
 
   return `% brief document
@@ -31,17 +31,15 @@ export function brief(options: IDocProps) {
 
 \\setkomavar{subject}{${subject}}
 
-\\setkomavar{yourref}[${yourRefName}]{${yourRef}}
-\\setkomavar{yourmail}{${yourMail}}
-\\setkomavar{myref}{${myRef}}
-\\setkomavar{customer}{${customer}}
-\\setkomavar{invoice}{${invoice}}
+${yourRef ? `\\setkomavar{yourref}[${yourRefName}]{${yourRef}}` : ''}
+${yourMail ? `\\setkomavar{yourmail}{${yourMail}}` : ''}
+${myRef ? `\\setkomavar{myref}{${myRef}}` : ''}
+${customer ? `\\setkomavar{customer}{${customer}}` : ''}
+${invoice ? `\\setkomavar{invoice}{${invoice}}` : ''}
+${signature ? `\\setkomavar{signature}{${signature}}` : ''}
+${specialMail ? `\\setkomavar{specialmail}{${specialMail}}` : ''}
 
-\\setkomavar{date}{${date}}
-
-%\\setkomavar{signature}{${signature}}
-
-\\setkomavar{specialmail}{${specialMail}}
+${date ? `\\setkomavar{date}{${date}}` : ''}
 
 \\begin{document}
 \\begin{letter}{${convertLineBreaks(address)}}
@@ -52,9 +50,9 @@ export function brief(options: IDocProps) {
 
     \\closing{${closing}}
 
-    \\ps{${ps}}
+    ${ps ? `\\ps{${ps}}` : ''}
 
-    %\\encl{${enclosing}}
+    ${enclosing ? `\\encl{${enclosing}}` : ''}
 
 \\end{letter}
 \\end{document}`