Add support for nested json metadata.

lib/mbtiles.js

@@ -229,6 +229,18 @@ MBTiles.prototype.getInfo = function(callback) {
         if (err && err.errno !== 1) return callback(err);
         if (rows) rows.forEach(function(row) {
             switch (row.name) {
+            // The special "json" key/value pair allows JSON to be serialized
+            // and merged into the metadata of an MBTiles based source. This
+            // enables nested properties and non-string datatypes to be
+            // captured by the MBTiles metadata table.
+            case 'json':
+                try { var jsondata = JSON.parse(row.value); }
+                catch (err) { return callback(err); }
+                Object.keys(jsondata).reduce(function(memo, key) {
+                    memo[key] = memo[key] || jsondata[key];
+                    return memo;
+                }, info);
+                break;
             case 'minzoom':
             case 'maxzoom':
                 info[row.name] = parseInt(row.value, 10);
@@ -537,11 +549,21 @@ MBTiles.prototype.putInfo = function(data, callback) {
     if (!this.open) return callback(new Error('MBTiles not yet loaded'));
     if (!this._isWritable) return callback(new Error('MBTiles not in write mode'));
 
+    var jsondata;
     var stmt = this._db.prepare('REPLACE INTO metadata (name, value) VALUES (?, ?)');
     stmt.on('error', callback);
     for (var key in data) {
-        stmt.run(key, String(data[key]));
+        // If a data property is a javascript hash/object, slip it into
+        // the 'json' field which contains stringified JSON to be merged
+        // in at read time. Allows nested/deep metadata to be recorded.
+        if (typeof data[key] === 'object' && !Array.isArray(data[key])) {
+            jsondata = jsondata || {};
+            jsondata[key] = data[key];
+        } else {
+            stmt.run(key, String(data[key]));
+        }
     }
+    if (jsondata) stmt.run('json', JSON.stringify(jsondata));
 
     var mbtiles = this;
     stmt.finalize(function(err) {

test/info.test.js

@@ -30,7 +30,8 @@ describe('info', function() {
                     formatter: null,
                     center: [ 0, 7.500000001278025, 2 ],
                     bounds: [ -179.9999999749438, -69.99999999526695, 179.9999999749438, 84.99999999782301 ],
-
+                    // Test that json data is merged in.
+                    level1: { level2: 'property' },
                     // These aren't part of TileJSON, but exist in an MBTiles file.
                     filesize: 561152,
                     type: 'baselayer',
@@ -45,6 +46,11 @@ describe('info', function() {
     it('get/put metadata from empty file', function(done) {
         this.timeout(10e3);
 
+        var info = {
+            version: '1.0.0',
+            level1: { level2: 'property' }
+        };
+
         new MBTiles(fixtures.empty, function(err, mbtiles) {
             assert.ifError(err);
 
@@ -58,14 +64,14 @@ describe('info', function() {
                     scheme: "tms"
                 }, data);
 
-                mbtiles.putInfo({ version: '1.0.0' }, function(err) {
+                mbtiles.putInfo(info, function(err) {
                     assert.ok(err);
                     assert.equal(err.message, 'MBTiles not in write mode');
 
                     mbtiles.startWriting(function(err) {
                         assert.ifError(err);
 
-                        mbtiles.putInfo({ version: '1.0.0' }, function(err) {
+                        mbtiles.putInfo(info, function(err) {
                             assert.ifError(err);
 
                             mbtiles.stopWriting(function(err) {
@@ -79,7 +85,8 @@ describe('info', function() {
                                         filesize: 0,
                                         id: "empty",
                                         scheme: "tms",
-                                        version: "1.0.0"
+                                        version: "1.0.0",
+                                        level1: { level2: "property" },
                                     }, data);
 
                                     done();