升级 sortAndFilterJson 到 stringifyOrdered，能和schemaColumns缺省值保持一致，并能把嵌套对象也按顺序输出。

index.js

@@ -12,17 +12,96 @@ module.exports = {
     }
   },
 
-  sortAndFilterJson({ fields, entity, exclude = [] } = {}) {
-    const newEntity = {}
-    for (let key of Object.keys(fields).sort()) {
-      if (typeof (entity[key] !== 'undefined') && !Number.isNaN(entity[key]) && entity[key] !== Infinity) {
-        newEntity[key] = entity[key]
+  // 按顺序展开，哪怕嵌套。
+  stringifyOrdered (obj, {cmp, cycles = false, space = '', replacer, schemaColumns, excludeKeys = []} = {}) {
+
+    /* 这个解决方法不考虑缺省值，不能把嵌套对象也按顺序展开。*/
+//    return JSON.stringify(obj, Object.keys(schemaColumns || entity).sort().filter(key => ! excludeKeys.includes(key))) // JSON.stringify 可根据第二个数组参数的顺序排序
+
+    let newObj = {}
+    if (schemaColumns) {
+      for (let key in schemaColumns){
+        if (schemaColumns.hasOwnProperty(key) && ! schemaColumns[key].hashExclusive && ! excludeKeys.includes(key)) {
+          // JSON.stringify (包括本函数）会把 NaN 或 Infinity 输出为 null，会把 undefined 忽略掉。
+          // 而在typeorm sqlite数据库中，undefined 会自动存为 schemaColumns[key].default 或 null。从数据库读出时，就会和事先JSON.stringify的结果不一致。
+          // 为了和数据库保持一致习惯，对schemaColumns里的键值最好把 undefined 也设为 default 或 null。
+          if (obj[key] === undefined || Number.isNaN(obj[key]) || obj[key] === Infinity) {
+            newObj[key] = schemaColumns[key].default || null
+            obj[key] = schemaColumns[key].default || null // 确保内存中的数据和数据库保持一致
+          }else {
+            newObj[key] = obj[key]
+          }
+        }
       }
+    }else{
+      newObj = obj
     }
-    for (let exkey of exclude) {
-      delete newEntity[exkey]
-    }
-    return JSON.stringify(newEntity)
+
+    /* 以下代码来自 https://github.com/substack/json-stable-stringify 可把嵌套的复杂值也按顺序输出，例如 { c: 8, b: [{z:6,y:5,x:4},7], a: 3 } */
+    if (typeof space === 'number') space = Array(space+1).join(' ')
+    var cycles = (typeof cycles === 'boolean') ? cycles : false
+    var replacer = replacer || function(key, value) { return value }
+
+    var cmp = cmp && (function (f) {
+        return function (node) {
+            return function (a, b) {
+                var aobj = { key: a, value: node[a] }
+                var bobj = { key: b, value: node[b] }
+                return f(aobj, bobj)
+            }
+        }
+    })(cmp)
+
+    var seen = []
+    return (function stringify (parent, key, node, level) {
+        var indent = space ? ('\n' + new Array(level + 1).join(space)) : ''
+        var colonSeparator = space ? ': ' : ':'
+
+        if (node && node.toJSON && typeof node.toJSON === 'function') {
+            node = node.toJSON()
+        }
+
+        node = replacer.call(parent, key, node)
+
+        if (node === undefined) {
+            return
+        }
+        if (typeof node !== 'object' || node === null) {
+            return JSON.stringify(node)
+        }
+        if (Array.isArray(node)) {
+            var out = []
+            for (var i = 0; i < node.length; i++) {
+                var item = stringify(node, i, node[i], level+1) || JSON.stringify(null)
+                out.push(indent + space + item)
+            }
+            return '[' + out.join(',') + indent + ']'
+        }
+        else {
+            if (seen.indexOf(node) !== -1) {
+                if (cycles) return JSON.stringify('__cycle__')
+                throw new TypeError('Converting circular structure to JSON')
+            }
+            else seen.push(node)
+
+            var keys = Object.keys(node).sort(cmp && cmp(node))
+            var out = []
+            for (var i = 0; i < keys.length; i++) {
+                var key = keys[i]
+                var value = stringify(node, key, node[key], level+1)
+
+                if(!value) continue
+
+                var keyValue = JSON.stringify(key)
+                    + colonSeparator
+                    + value
+                
+                out.push(indent + space + keyValue)
+            }
+            seen.splice(seen.indexOf(node), 1)
+            return '{' + out.join(',') + indent + '}'
+        }
+    })({ '': newObj }, '', newObj, 0)
   },
 
   name2port(name='') {