Merge pull request #809 from Dletta/promise

added promise wrappers to core API

lib/promise.js

@@ -0,0 +1,124 @@
+/* Promise Library v1.0 for GUN DB
+*  Turn any part of a gun chain into a promise, that you can then use
+*  .then().catch() pattern.
+*  In normal gun doing var item = gun.get('someKey'), gun returns a reference
+*  to the someKey synchroneously. Using a reference is quite helpful in making
+*  graph structures, so I have chosen to follow the following paradigm.
+*  Whenever a promise is resolved, gun will return an object of data, I will
+*  wrap that data in an object together with the reference like so:
+*  {ref: gunRef, data: data}.
+* This code is freely given in the spirit of open source MIT license.
+* Author: Jachen Duschletta / 2019
+*/
+
+/*
+* Function promOnce
+* @param limit - due to promises resolving too fast if we do not set a timer
+*  we will not be able receive any data back from gun before returning the promise
+*  works both following a Chain.get and a Chain.map (limit only applies to map)
+*  If no limit is chosen, defaults to 100 ms (quite sufficient to fetch about 2000 nodes or more)
+* @param opt - option object
+* @return {ref: gunReference, data: object / string (data), key: string (soulOfData)}
+*/
+
+Gun.chain.promOnce = async function (limit, opt) {
+ var gun = this, cat = gun._;
+ if(!limit){limit = 100}
+ if(cat.subs){
+  var array = [];
+  gun.map().once((data, key)=>{
+    var gun = this;
+    array.push(new Promise((res, rej)=>{
+      res({ref: gun, data:data, key:key});
+    })
+   )
+ }, opt);
+  await sleep(limit);
+  return Promise.all(array)
+} else {
+  return (new Promise((res, rej)=>{
+    gun.once(function (data, key) {
+      var gun = this;
+      res({ref:gun,data:data,key:key});
+      }, opt);
+    }))
+  }
+ var chain = gun.chain();
+ return chain;
+}
+
+function sleep (limit) {
+ return (new Promise((res, rej)=>{
+   setTimeout(res, limit);
+ }))
+}
+
+/*
+* Function promPut
+* @param item (string / object) - item to be put to that key in the chain
+* @param opt - option object
+* @return object - Returns an object with the ref to that node that was just
+*  created as well as the 'ack' which acknowledges the put was succesful
+*  object {ref: gunReference, ack: acknowledgmentObject}
+* If put had an error we can catch the return via .catch
+*/
+
+Gun.chain.promPut = async function (item, opt) {
+  var gun = this;
+  return (new Promise((res, rej)=>{
+    gun.put(item, function(ack) {
+        if(ack.err){rej(ack.err)}
+        res({ref:gun, ack:ack});
+    }, opt);
+  }))
+}
+
+/*
+* Function promSet
+* @param item (string / object) - item to be set into a list at this key
+* @param opt - option object
+* @return object - Returns object with the ref to that node that was just
+*  created as well as the 'ack' which acknowledges the set was succesful
+*  object {ref: gunReference, ack: acknowledgmentObject}
+* If set had an error we can catch the return via .catch
+*/
+
+Gun.chain.promSet = async function(item, opt){
+	var gun = this, soul;
+  var cb = cb || function(){};
+	opt = opt || {}; opt.item = opt.item || item;
+  return (new Promise(async function (res,rej) {
+    if(soul = Gun.node.soul(item)){ item = Gun.obj.put({}, soul, Gun.val.link.ify(soul)) }
+		if(!Gun.is(item)){
+			if(Gun.obj.is(item)){;
+				item = await gun.back(-1).get(soul = soul || Gun.node.soul(item) || gun.back('opt.uuid')()).promPut(item);
+        item = item.ref;
+			}
+			res(gun.get(soul || (Gun.state.lex() + Gun.text.random(7))).promPut(item));
+		}
+		item.get(function(soul, o, msg){
+      var ack = {};
+			if(!soul){ rej({ack:{err: Gun.log('Only a node can be linked! Not "' + msg.put + '"!')}} ) }
+			gun.put(Gun.obj.put({}, soul, Gun.val.link.ify(soul)), cb, opt);
+		},true);
+		res({ref:item, ack:{ok:0}});
+  }))
+}
+
+/*
+* Function promOn
+* @param callback (function) - function to be called upon changes to data
+* @param option (object) - {change: true} only allow changes to trigger the callback
+* @return - data and key
+* subscribes callback to data
+*/
+
+Gun.chain.promOn = async function (callback, option) {
+  var gun = this;
+  return (new Promise((res, rej)=>{
+    gun.on(function (data, key){
+      callback(data, key);
+      res(data, key);
+    }, option);
+  }));
+}