Merge pull request #62 from phuu/gen-batch-pairs

Add generateBatch method to db API.

README.md

@@ -486,6 +486,21 @@ stream.on("close", function() {
 });
 ```
 
+### Generate batch operations
+
+You can also generate a `put` and `del` batch, so you can
+manage the batching yourself:
+
+```javascript
+var triple = { subject: "a", predicate: "b", object: "c" };
+
+// Produces a batch of put operations
+var putBatch = db.generateBatch(triple);
+
+// Produces a batch of del operations
+var delBatch = db.generateBatch(triple, 'del');
+```
+
 ## LevelUp integration
 
 LevelGraph allows to leverage the full power of all

lib/levelgraph.js

@@ -96,6 +96,7 @@ module.exports = function levelgraph(leveldb, options, readyCallback) {
     , nav: function(start) {
       return new Navigator({ start: start, db: this });
     }
+    , generateBatch: utilities.generateBatch
   };
 
   db.joinStream = function(a, b, c) {
@@ -183,7 +184,7 @@ doAction = function(action, leveldb) {
     }
 
     var actions = triples.reduce(function(acc, triple) {
-      return acc.concat(utilities.genActions(action, triple));
+      return acc.concat(utilities.generateBatch(triple, action));
     }, []);
 
     leveldb.batch(actions, cb);

lib/utilities.js

@@ -131,14 +131,17 @@ function createQuery(pattern, options) {
 
 module.exports.createQuery = createQuery;
 
-function genActions(action, triple) {
+function generateBatch(triple, action) {
+  if (!action) {
+    action = 'put';
+  }
   var json = JSON.stringify(triple);
   return genKeys(triple).map(function(key) {
     return { type: action, key: key, value: json };
   });
 }
 
-module.exports.genActions = genActions;
+module.exports.generateBatch = generateBatch;
 
 function materializer(pattern, data) {
   return Object.keys(pattern)

test/triple_store_spec.js

@@ -393,3 +393,36 @@ describe('deferred open support', function() {
     });
   });
 });
+
+describe('generateBatch', function () {
+  var db, leveldb = leveldb;
+
+  beforeEach(function() {
+    leveldb = level();
+    db = levelgraph(leveldb);
+  });
+
+  afterEach(function(done) {
+    db.close(done);
+  });
+
+  it('should generate a batch from a triple', function() {
+    var triple = { subject: 'a', predicate: 'b', object: 'c' };
+    var ops = db.generateBatch(triple);
+    expect(ops).to.have.property('length', 6);
+    ops.forEach(function (op) {
+      expect(op).to.have.property('type', 'put');
+      expect(JSON.parse(op.value)).to.eql(triple);
+    });
+  });
+
+  it('should generate a batch of type', function() {
+    var triple = { subject: 'a', predicate: 'b', object: 'c' };
+    var ops = db.generateBatch(triple, 'del');
+    expect(ops).to.have.property('length', 6);
+    ops.forEach(function (op) {
+      expect(op).to.have.property('type', 'del');
+      expect(JSON.parse(op.value)).to.eql(triple);
+    });
+  });
+});