fix dynamodb-toolbox#68 with dependency graphs

Author: jeremydaly

lib/normalizeData.js

@@ -14,10 +14,36 @@ module.exports = (DocumentClient) => (schema,linked,data,filter=false) => {
 
   // Intialize validate type
   const validateType = validateTypes(DocumentClient)
+
+  // Build and execute defaults dependency graph
+  const dependsOn = (map,attr) => {  
+    // If the default depends on other attributes
+    if (schema[attr].dependsOn) {
+      (Array.isArray(schema[attr].dependsOn) ? schema[attr].dependsOn : [schema[attr].dependsOn]).forEach(dependent => {
+        // If the dependent is a valid attribute or alias
+        if (schema[dependent]) {          
+          // If the dependent is a function
+          if (typeof map[dependent] === 'function') {   
+            // Resolve the dependency graph
+            map = dependsOn(map,dependent)
+          }
+        } else {
+          error(`'${dependent}' is not a valid attribute or alias name`)
+        }
+      }) // end dependency loop
+
+      map[attr] = map[attr](map)
+      return map
+    } else {
+      map[attr] = map[attr](map)
+      if (schema[attr].alias) map[schema[attr].alias] = map[attr]
+      if (schema[attr].map) map[schema[attr].map] = map[attr]
+      return map
+    }
+  } // end dependsOn
 
   // Generate normalized data object
   let dataMap = Object.keys(data).reduce((acc,field) => {
-
     // Return a map with normalized data and alias references
     return Object.assign(acc,
       schema[field] ? { 
@@ -27,17 +53,28 @@ module.exports = (DocumentClient) => (schema,linked,data,filter=false) => {
       : filter ? {} // this will filter out non-mapped fields
       : field === '$remove' ? { data: { ...acc.data, $remove: data[field] } } // support for removes
       : error(`Field '${field}' does not have a mapping or alias`)
-    )
-    
+    )    
   },{ data: {}, aliases: {} })
 
-  
+  // Create a combined data object for defaults
+  let defaultMap = { ...dataMap.data, ...dataMap.aliases }
+  const defaults = Object.keys(defaultMap).reduce((acc,attr) => {
+    // If a function, resolve the dependency graph
+    if (typeof defaultMap[attr] === 'function') { 
+      let map = dependsOn(defaultMap,attr)
+      defaultMap = map
+    }
+    return Object.assign(acc, { [attr]: defaultMap[attr] })
+  },{})
+
+
   // Generate final data and evaluate function expressions
   let _data = Object.keys(dataMap.data).reduce((acc,field) => {
     return Object.assign(acc, { 
-      [field]: typeof dataMap.data[field] === 'function' ? dataMap.data[field]({ ...dataMap.data, ...dataMap.aliases }) : dataMap.data[field]
+      [field]: defaults[field]
     })
   },{})
+  
 
   // Process linked
   let composites = Object.keys(linked).reduce((acc,attr) => {
@@ -70,3 +107,24 @@ module.exports = (DocumentClient) => (schema,linked,data,filter=false) => {
   return Object.assign(composites,_data)
 
 } // end normalizeData
+
+
+
+
+
+// Generate final data and evaluate function expressions
+// let _data = Object.keys(dataMap.data).reduce((acc,field) => {
+//   return Object.assign(acc, { 
+//     [field]: typeof dataMap.data[field] === 'function' ? dataMap.data[field](defaults) : dataMap.data[field]
+//   })
+// },{})
+
+// console.log(_data)
+
+
+
+// map[schema[attr].dependsOn] = typeof map[schema[attr].dependsOn] === 'function' ? 
+//   dependsOn(map,schema[attr].dependsOn) // map[schema[attr].dependsOn](map) 
+//   : map[schema[attr].dependsOn]
+// return { map, val: map[attr](map) }
+// return dependsOn(map,attr)

lib/parseMapping.js

@@ -17,6 +17,10 @@ module.exports = (field,config,track) => {
       case 'type':
       case 'default':
         break
+      case 'dependsOn':
+        if (typeof config[prop] !== 'string' && !Array.isArray(config[prop]))
+          error(`'dependsOn' must be the string name of an attribute or alias`)
+        break
       case 'transform':
         if (typeof config[prop] !== 'function') error(`'${prop}' must be a function`)
         break