fix(draggable plugin): fix node insert error after drop

fix #51

Author: phphe

src/plugins/draggable/Draggable.vue

@@ -264,11 +264,28 @@ export default {
             const startSiblings = startParentPath.length === 0 ? startTree.treeData : startParent.children
             const startIndex = hp.arrayLast(startPath)
             startSiblings.splice(startIndex, 1)
-            // update targetPath if isDownwardsSameLevelMove
-            if (store.isDownwardsSameLevelMove) {
-              targetPath = targetPath.slice(0)
-              const endIndex = startPath.length - 1
-              targetPath[endIndex] -= 1
+            // remove node from the starting position may affect the target path.
+            // example
+            //  startPath   targetPath
+            //  [0]         [1]
+            //  [0]         [1, 0]
+            //  [3, 1]      [3, 3]
+            //  [3, 1]      [3, 3, 5]
+            // above targetPaths should be transformed to [0], [0, 0] [3, 2] [3, 2, 5]
+            if (startTree === targetTree) {
+              if (startPath.length <= targetPath.length) {
+                const sw = startPath.slice(0, startPath.length - 1) // without end
+                const tw = targetPath.slice(0, sw.length) // same length with sw
+                if (sw.toString() === tw.toString()) {
+                  const endIndex = sw.length
+                  if (startPath[endIndex] < targetPath[endIndex]) {
+                    targetPath = targetPath.slice(0) // create a copy of targetPath
+                    targetPath[endIndex] -= 1
+                  } else if (startPath[endIndex] === targetPath[endIndex]) {
+                    console.error('Draggable.afterDrop: That is impossible!');
+                  }
+                }
+              }
             }
           }
           // insert to target position

src/plugins/draggable/draggable.js

@@ -466,7 +466,6 @@ export default function makeTreeDraggable(treeEl, options = {}) {
         }
         //
         store.targetPath = options.getPathByBranchEl(placeholder)
-        store.isDownwardsSameLevelMove = isDownwardsSameLevelMove()
         let pathChanged = isPathChanged()
         store.targetPathNotEqualToStartPath = pathChanged
         store.pathChangePrevented = false
@@ -496,15 +495,21 @@ export default function makeTreeDraggable(treeEl, options = {}) {
       }
       //
       function isPathChanged() {
-        const {startTree, targetTree, startPath, targetPath, isDownwardsSameLevelMove} = store
-        if (isDownwardsSameLevelMove) {
-          return hp.arrayLast(startPath) < hp.arrayLast(targetPath) - 1 // if equal, not moved
-        }
-        return startTree !== targetTree || startPath.toString() !== targetPath.toString()
-      }
-      function isDownwardsSameLevelMove() {
         const {startTree, targetTree, startPath, targetPath} = store
-        return startTree === targetTree && startPath.length === targetPath.length && startPath.slice(0, startPath.length - 1).toString() === targetPath.slice(0, targetPath.length - 1).toString() && hp.arrayLast(startPath) < hp.arrayLast(targetPath)
+        if (startTree === targetTree && startPath.length === targetPath.length) {
+          if (startPath.toString() === targetPath.toString()) {
+            return false
+          } else {
+            // downward same-level move, the end of targetPath is 1 more than real value 
+            // 同级向下移动时, targetPath的末位比真实值大1
+            const t = startPath.slice(0)
+            t[t.length - 1] ++
+            if (t.toString() === targetPath.toString()) {
+              return false
+            }
+          }
+        }
+        return true
       }
     },
   })