merging values

Author: Krzysztof Borowy

android/src/main/java/com/reactnativecommunity/asyncstorage/AsyncStoragePackage.java

@@ -30,7 +30,6 @@ public List<NativeModule> createNativeModules(ReactApplicationContext reactConte
                 NativeModule inst = (NativeModule) storageClass.getDeclaredConstructor(new Class[]{ReactContext.class}).newInstance(reactContext);
                 moduleList.add(inst);
             } catch (Exception e) {
-                // todo notify about potential issues
                 String message = "Something went wrong when initializing module:"
                         + "\n"
                         + e.getCause().getClass()

android/src/main/java/com/reactnativecommunity/asyncstorage/next/ArgumentHelpers.kt

@@ -2,6 +2,8 @@ package com.reactnativecommunity.asyncstorage.next
 
 import com.facebook.react.bridge.Arguments
 import com.facebook.react.bridge.ReadableArray
+import org.json.JSONException
+import org.json.JSONObject
 
 fun ReadableArray.toEntryList(): List<Entry> {
     val list = mutableListOf<Entry>()
@@ -50,4 +52,35 @@ fun List<Entry>.toKeyValueArgument(): ReadableArray {
     }
 
     return args
+}
+
+fun String?.isValidJson(): Boolean {
+    if (this == null) return false
+
+    return try {
+        JSONObject(this)
+        true
+    } catch (e: JSONException) {
+        false
+    }
+}
+
+fun JSONObject.mergeWith(newObject: JSONObject): JSONObject {
+
+    val keys = newObject.keys()
+    val mergedObject = JSONObject(this.toString())
+
+    while (keys.hasNext()) {
+        val key = keys.next()
+        val curValue = this.optJSONObject(key)
+        val newValue = newObject.optJSONObject(key)
+
+        if (curValue != null && newValue != null) {
+            val merged = curValue.mergeWith(newValue)
+            mergedObject.put(key, merged)
+        } else {
+            mergedObject.put(key, newObject.get(key))
+        }
+    }
+    return mergedObject
 }

android/src/main/java/com/reactnativecommunity/asyncstorage/next/StorageModule.kt

@@ -22,8 +22,8 @@ class StorageModule(reactContext: ReactContext) : ReactContextBaseJavaModule(),
 
     /**
      * Todo:
-     *  - MultiMerge
-     *  - Documenting the migration, access from Brownfield and error handling
+     *  - Documenting the migration,
+     *  - access from Native (Java interop)
      */
 
     @ReactMethod
@@ -51,8 +51,14 @@ class StorageModule(reactContext: ReactContext) : ReactContextBaseJavaModule(),
         }
     }
 
-    // @ReactMethod
-    // fun multiMerge(val keyValueArray: ReadableArray, cb: Callback) {}
+    @ReactMethod
+    fun multiMerge(keyValueArray: ReadableArray, cb: Callback) {
+        launch(createExceptionHandler(cb)) {
+            val entries = keyValueArray.toEntryList()
+            storage.mergeValues(entries)
+            cb(null)
+        }
+    }
 
     @ReactMethod
     fun getAllKeys(cb: Callback) {

android/src/main/java/com/reactnativecommunity/asyncstorage/next/StorageSupplier.kt

@@ -15,6 +15,7 @@ import androidx.room.Transaction
 import androidx.room.Update
 import androidx.room.migration.Migration
 import androidx.sqlite.db.SupportSQLiteDatabase
+import org.json.JSONObject
 
 private const val DATABASE_VERSION = 2
 private const val DATABASE_NAME = "AsyncStorage"
@@ -32,7 +33,25 @@ data class Entry(
 @Dao
 private interface StorageDao {
 
-    // fun mergeValues() // todo
+    @Transaction
+    fun mergeValues(entries: List<Entry>) {
+        val currentDbEntries = getValues(entries.map { it.key })
+        val newEntries = mutableListOf<Entry>()
+
+        entries.forEach { newEntry ->
+            val oldEntry = currentDbEntries.find { it.key == newEntry.key }
+            if (oldEntry?.value == null) {
+                newEntries.add(newEntry)
+            } else if (!oldEntry.value.isValidJson() || !newEntry.value.isValidJson()) {
+                newEntries.add(newEntry)
+            } else {
+                val newValue =
+                    JSONObject(oldEntry.value).mergeWith(JSONObject(newEntry.value)).toString()
+                newEntries.add(newEntry.copy(value = newValue))
+            }
+        }
+        setValues(newEntries)
+    }
 
     @Transaction
     @Query("SELECT * FROM $TABLE_NAME WHERE `$COLUMN_KEY` IN (:keys)")
@@ -138,7 +157,7 @@ interface AsyncStorageAccess {
     suspend fun removeValues(keys: List<String>)
     suspend fun getKeys(): List<String>
     suspend fun clear()
-    // suspend fun mergeValues() // todo
+    suspend fun mergeValues(entries: List<Entry>)
 }
 
 class StorageSupplier private constructor(db: StorageDb) : AsyncStorageAccess {
@@ -153,6 +172,7 @@ class StorageSupplier private constructor(db: StorageDb) : AsyncStorageAccess {
     override suspend fun getValues(keys: List<String>) = access.getValues(keys)
     override suspend fun setValues(entries: List<Entry>) = access.setValues(entries)
     override suspend fun removeValues(keys: List<String>) = access.removeValues(keys)
+    override suspend fun mergeValues(entries: List<Entry>) = access.mergeValues(entries)
     override suspend fun getKeys() = access.getKeys()
     override suspend fun clear() = access.clear()
 }

example/App.js

@@ -128,7 +128,7 @@ const styles = StyleSheet.create({
     padding: 8,
   },
   exampleContainer: {
-    padding: 16,
+    padding: 4,
     backgroundColor: '#FFF',
     borderColor: '#EEE',
     borderTopWidth: 1,

example/examples/Basic.js

@@ -1,17 +1,33 @@
 import React from 'react';
-import {View, Text, Button, StyleSheet, ScrollView, TextInput, NativeModules} from 'react-native';
+import {View, Text, Button, StyleSheet, ScrollView, TextInput} from 'react-native';
 import AsyncStorage from '@react-native-async-storage/async-storage';
 
-const RCTAsyncStorage = NativeModules.RNC_AsyncSQLiteDBStorage ||
-  NativeModules.RNCAsyncStorage;
 
+const mergeInitialValue = {
+  initial: 'keep',
+  override1: 'override',
+  nested: {
+    nestedValue: 'keep',
+    override2: 'override',
+    deeper: {
+      deeperValue: 'keep',
+      override3: 'override',
+    },
+  },
+};
 
 function NextExample() {
   const [keys, setKeys] = React.useState([]);
   const [error, setError] = React.useState(null);
   const [inputKey, setInputKey] = React.useState();
   const [inputValue, setInputValue] = React.useState();
   const [value, setValue] = React.useState();
+  const [mergedValue, setMergedValue] = React.useState();
+  const [overrideValue, setOverrideValue] = React.useState({
+    override1: '',
+    override2: '',
+    override3: '',
+  });
 
 
   function runWithCatch(block) {
@@ -59,14 +75,58 @@ function NextExample() {
     await AsyncStorage.clear();
   }
 
+  async function resetMergedValue() {
+    await AsyncStorage.setItem('MERGER', JSON.stringify(mergeInitialValue));
+    const saved = await AsyncStorage.getItem('MERGER');
+    setMergedValue(JSON.parse(saved));
+  }
+
+  async function readMergedValue() {
+    const saved = await AsyncStorage.getItem('MERGER');
+    setMergedValue(saved ? JSON.parse(saved) : {});
+  }
+
+  async function mergeValues() {
+    const {override1, override2, override3} = overrideValue;
+
+    // leave out empty inputs
+    const toMerge = {};
+    if (override1) {
+      toMerge.override1 = override1;
+    }
+    if (override2) {
+      toMerge.nested = {
+        override2: override2,
+      };
+    }
+    if (override3) {
+      if (!toMerge.nested) {
+        toMerge.nested = {
+          deeper: {
+            override3: override3,
+          },
+        };
+      } else {
+        toMerge.nested.deeper = {
+          override3: override3,
+        };
+      }
+    }
+
+
+    await AsyncStorage.mergeItem('MERGER', JSON.stringify(toMerge));
+  }
+
+
   return <ScrollView contentContainerStyle={{flexGrow: 1}}>
 
-    {error ? <Text style={{fontSize: 18, color: 'red'}}>{error}</Text> : null}
+    {error ? <Text style={styles.error}>{error}</Text> : null}
 
     <View style={styles.example}>
+      <Text style={styles.title}>Basic operations</Text>
       <TextInput onChangeText={setInputKey} value={inputKey} style={styles.input} placeholder="key"/>
       <TextInput onChangeText={setInputValue} value={inputValue} style={styles.input} placeholder="value"/>
-      <View style={{flexDirection: 'row', justifyContent: 'space-around'}}>
+      <View style={styles.row}>
         <Button title="Read" onPress={runWithCatch(readValue)}/>
         <Button title="Save" onPress={runWithCatch(saveValue)}/>
         <Button title="Delete" onPress={runWithCatch(removeValue)}/>
@@ -75,24 +135,54 @@ function NextExample() {
     </View>
 
     <View style={styles.example}>
-      <Text style={{fontSize: 16, fontWeight: '700'}}>Crash scenarios</Text>
-      <View style={{flexDirection: 'row', justifyContent: 'space-around'}}>
+      <Text style={styles.title}>Crash scenarios</Text>
+      <View style={styles.row}>
         <Button title="Key null" onPress={runWithCatch(crashKeyNull)}/>
         <Button title="Key not string" onPress={runWithCatch(crashKeyNotString)}/>
         <Button title="Wrong value type" onPress={runWithCatch(crashValueType)}/>
       </View>
     </View>
 
     <View style={styles.example}>
-      <View style={{flexDirection: 'row', justifyContent: 'space-around'}}>
+      <Text style={styles.title}>Merging</Text>
+      <View style={styles.row}>
+        <Text>{`Value:\n\n${JSON.stringify(mergedValue, null, 2)}`}</Text>
+        <Text>{`Merge with:\n\n${JSON.stringify(overrideValue, null, 2)}`}</Text>
+      </View>
+      <View style={styles.row}>
+        <Button title="Read" onPress={runWithCatch(readMergedValue)}/>
+        <Button title="Reset" onPress={runWithCatch(resetMergedValue)}/>
+        <Button title="Merge" onPress={runWithCatch(mergeValues)}/>
+      </View>
+      <View>
+        <TextInput
+          onChangeText={t => setOverrideValue(c => ({...c, override1: t}))}
+          value={overrideValue.override1}
+          style={styles.input} placeholder="override1"
+        />
+        <TextInput
+          onChangeText={t => setOverrideValue(c => ({...c, override2: t}))}
+          value={overrideValue.override2}
+          style={styles.input} placeholder="override2"
+        />
+        <TextInput
+          onChangeText={t => setOverrideValue(c => ({...c, override3: t}))}
+          value={overrideValue.override3}
+          style={styles.input} placeholder="override3"
+        />
+      </View>
+    </View>
+
+    <View style={styles.example}>
+      <Text style={styles.title}>Display all keys</Text>
+      <View style={styles.row}>
         <Button title="Get all keys" onPress={runWithCatch(getAllKeys)}/>
       </View>
-      <Text style={{fontWeight: '700'}}>Keys:</Text>
       <Text>{keys.join(', ')}</Text>
     </View>
 
     <View style={styles.example}>
-      <Text style={{fontSize: 16}}>Clear database entries</Text>
+      <Text style={styles.title}>Clear database entries</Text>
       <Button title="clear" onPress={runWithCatch(clearDb)}/>
     </View>
   </ScrollView>;
@@ -101,7 +191,8 @@ function NextExample() {
 
 const styles = StyleSheet.create({
   example: {
-    paddingVertical: 24,
+    paddingBottom: 24,
+    paddingTop: 8,
     borderBottomWidth: 1,
     borderBottomColor: '#e3e3e3',
     borderStyle: 'solid',
@@ -112,6 +203,19 @@ const styles = StyleSheet.create({
     borderColor: '#eee',
     borderStyle: 'solid',
   },
+  error: {
+    fontSize: 18,
+    color: 'red',
+  },
+  row: {
+    flexDirection: 'row',
+    justifyContent: 'space-around',
+  },
+  title: {
+    fontSize: 16,
+    fontWeight: '700',
+    paddingBottom: 12,
+  },
 });