Add support for invoices that accept any amount

README.md

@@ -87,21 +87,25 @@ If a currency and amount were provided, they'll be available under `quoted_{curr
 Returns `201 Created` and the invoice on success.
 
 ```bash
-$ curl $CHARGE/invoice -d msatoshi=10000
+$ curl -X POST $CHARGE/invoice -d msatoshi=10000
 {"id":"KcoQHfHJSx3fVhp3b1Y3h","msatoshi":"10000","status":"unpaid","rhash":"6823e46a08f50...",
  "payreq":"lntb100n1pd99d02pp...","created_at":1515369962,"expires_at":1515373562}
 
 # with fiat-denominated amounts
-$ curl $CHARGE/invoice -d currency=EUR -d amount=0.5
+$ curl -X POST $CHARGE/invoice -d currency=EUR -d amount=0.5
 {"id":"OYwwaOQAPMFvg039gj_Rb","msatoshi":"3738106","quoted_currency":"EUR","quoted_amount":"0.5",...}
 
+# without amount (accept all payments)
+$ curl -X POST $CHARGE/invoice
+{"id":"W8CF0UqY7qfAHCfnchqk9","msatoshi":null,...}
+
 # with metadata as application/json
-$ curl $CHARGE/invoice -H 'Content-Type: application/json' \
+$ curl -X POST $CHARGE/invoice -H 'Content-Type: application/json' \
   -d '{"msatoshi":7000,"metadata":{"customer_id":9817,"products":[593,182]}}'
 {"id":"PLKV1f8B7sth7w2OeDOt_","msatoshi":"7000","metadata":{"customer_id":9817,"products":[593,182]},...}
 
 # with metadata as application/x-www-form-urlencoded
-$ curl $CHARGE/invoice -d msatoshi=5000 -d metadata[customer_id]=9817 -d metadata[product_id]=7189
+$ curl -X POST $CHARGE/invoice -d msatoshi=5000 -d metadata[customer_id]=9817 -d metadata[product_id]=7189
 {"id":"58H9eoerBpKML9FvnMQtG","msatoshi":"5000","metadata":{"customer_id":"9817","product_id":"7189"},...}
 ```
 
@@ -156,7 +160,7 @@ For security reasons, the provided `url` should contain a secret token used to v
 and [here](https://github.com/ElementsProject/woocommerce-gateway-lightning/blob/84592d7bcfc41db129b02d1927a6060a05c5c11e/woocommerce-gateway-lightning.php#L109-L115)).
 
 ```bash
-$ curl $CHARGE/invoice/OYwwaOQAPMFvg039gj_Rb/webhook -d url=http://example.com/callback
+$ curl -X POST $CHARGE/invoice/OYwwaOQAPMFvg039gj_Rb/webhook -d url=http://example.com/callback
 Created
 ```
 

src/model.js

@@ -4,13 +4,19 @@ import { toMsat } from './lib/exchange-rate'
 const debug  = require('debug')('lightning-charge')
     , status = inv => inv.pay_index ? 'paid' : inv.expires_at > now() ? 'unpaid' : 'expired'
     , format = inv => ({ ...inv, completed: !!inv.pay_index, completed_at: inv.paid_at
-                       , status: status(inv), metadata: JSON.parse(inv.metadata) })
+                       , status: status(inv), msatoshi: (inv.msatoshi || null), metadata: JSON.parse(inv.metadata) })
     , now    = _ => Date.now() / 1000 | 0
 
 // @XXX the `completed` and `completed_at` field are deprecated
 // in favor `status` and `paid_at`, and will eventually be removed
 // from the public API.
 
+// @XXX invoices that accept any amount are stored as msatoshi='' (empty string)
+// and converted to null when formatted. this is due to sqlite's lack of support
+// for ALTER TABLE, which makes dropping the NOT NULL constraint complicated
+// (requires creating a new table, copying over the data and replacing the old one).
+// This will eventually be done in a future release.
+
 const defaultDesc = process.env.INVOICE_DESC_DEFAULT || 'Lightning Charge Invoice'
 
 module.exports = (db, ln) => {
@@ -18,8 +24,8 @@ module.exports = (db, ln) => {
     const { currency, amount, expiry, description, metadata, webhook } = props
 
     const id       = nanoid()
-        , msatoshi = props.msatoshi ? ''+props.msatoshi : await toMsat(currency, amount)
-        , lninv    = await ln.invoice(msatoshi, id, description || defaultDesc, expiry)
+        , msatoshi = props.msatoshi ? ''+props.msatoshi : currency ? await toMsat(currency, amount) : ''
+        , lninv    = await ln.invoice(msatoshi || 'any', id, description || defaultDesc, expiry)
 
     const invoice = {
             id, description, msatoshi

test/invoice.js

@@ -48,6 +48,12 @@ describe('Invoice API', function() {
         .expect(201)
         .expect(r => r.body.expires_at*1000 - Date.now() < 5000)
     )
+
+    it('can create invoices that accept any amount', () => {
+      charge.post('/invoice')
+        .expect(201)
+        .expect(r => r.body.msatoshi == null)
+    })
   })
 
   const mkInvoice = props =>

views/checkout.pug

@@ -26,12 +26,13 @@ body: .checkout.container
     .desc.col-sm-6
       h3= opt.title || 'Lightning Payment'
       h4= opt.desc || 'Pay with Lightning'
-    .amounts.col-sm-6
-      if quoted_currency
-        h3 #{ quoted_amount } #{ quoted_currency }
-        h4 #{ formatMsat(msatoshi) }
-      else
-        h3 #{ formatMsat(msatoshi) }
+    if msatoshi
+      .amounts.col-sm-6
+        if quoted_currency
+          h3 #{ quoted_amount } #{ quoted_currency }
+          h4 #{ formatMsat(msatoshi) }
+        else
+          h3 #{ formatMsat(msatoshi) }
 
   if status == 'paid'
     p.thankyou= opt.thank_you || 'Thank you! Your payment has been received.'