New SQLConnector.prototype.buildCount with support to querying relations

Extracted SQLConnector.prototype.buildCount from
SQLConnector.prototype.count to better test the built SQL.

lib/sql.js

@@ -1185,6 +1185,45 @@ SQLConnector.prototype.find = function(model, id, options, cb) {
 // Alias to `find`. Juggler checks `findById` only.
 Connector.defineAliases(SQLConnector.prototype, 'find', ['findById']);
 
+/**
+ * Build a SQL SELECT statement to count rows
+ * @param {String} model Model name
+ * @param {Object} where Where object
+ * @param {Object} options Options object
+ * @returns {ParameterizedSQL} Statement object {sql: ..., params: [...]}
+ */
+SQLConnector.prototype.buildCount = function(model, where, options) {
+  var haveRelationFilters = false;
+  if (where) {
+    var relations = this.getModelDefinition(model).model.relations;
+    if (relations) {
+      for (var key in where) {
+        if (key in relations) {
+          haveRelationFilters = true;
+          break;
+        }
+      }
+    }
+  }
+
+  var count = 'count(*)';
+  if (haveRelationFilters) {
+    var idColumn = this.columnEscaped(model, this.idColumn(model));
+    count = 'count(DISTINCT ' + idColumn + ')';
+  }
+
+  var stmt = new ParameterizedSQL('SELECT ' + count +
+    ' as "cnt" FROM ' + this.tableEscaped(model));
+
+  if (haveRelationFilters) {
+    var joinsStmts = this.buildJoins(model, where);
+    stmt = stmt.merge(joinsStmts);
+  }
+
+  stmt = stmt.merge(this.buildWhere(model, where));
+  return this.parameterize(stmt);
+};
+
 /**
  * Count all model instances by the where filter
  *
@@ -1202,10 +1241,8 @@ SQLConnector.prototype.count = function(model, where, options, cb) {
     where = tmp;
   }
 
-  var stmt = new ParameterizedSQL('SELECT count(*) as "cnt" FROM ' +
-    this.tableEscaped(model));
-  stmt = stmt.merge(this.buildWhere(model, where));
-  stmt = this.parameterize(stmt);
+  var stmt = this.buildCount(model, where, options);
+
   this.execute(stmt.sql, stmt.params,
     function(err, res) {
       if (err) {

test/sql.test.js

@@ -420,6 +420,40 @@ describe('sql connector', function() {
     });
   });
 
+  it('builds count', function() {
+    var sql = connector.buildCount('customer');
+    expect(sql.toJSON()).to.eql({
+      sql: 'SELECT count(*) as "cnt" FROM `CUSTOMER` ',
+      params: []
+    });
+  });
+
+  it('builds count with WHERE', function() {
+    var sql = connector.buildCount('customer', {name: 'John'});
+    expect(sql.toJSON()).to.eql({
+      sql: 'SELECT count(*) as "cnt" FROM `CUSTOMER` WHERE `CUSTOMER`.`NAME`=$1',
+      params: ['John']
+    });
+  });
+
+  it('builds count with WHERE and JOIN', function() {
+    var sql = connector.buildCount('customer', {
+      name: 'John',
+      orders: {
+        where: {
+          date: {between: ['2015-01-01', '2015-01-31']}
+        }
+      }
+    });
+    expect(sql.toJSON()).to.eql({
+      sql: 'SELECT count(DISTINCT `CUSTOMER`.`NAME`) as "cnt" FROM `CUSTOMER` ' +
+        'INNER JOIN ( SELECT `ORDER`.`CUSTOMER_NAME` FROM `ORDER` WHERE ' +
+        '`ORDER`.`DATE` BETWEEN $1 AND $2 ORDER BY `ORDER`.`ID` ) AS `ORDER` ' +
+        'ON `CUSTOMER`.`NAME`=`ORDER`.`CUSTOMER_NAME` WHERE `CUSTOMER`.`NAME`=$3',
+      params: ['2015-01-01', '2015-01-31', 'John']
+    });
+  });
+
   it('normalizes a SQL statement from string', function() {
     var sql = 'SELECT * FROM `CUSTOMER`';
     var stmt = new ParameterizedSQL(sql);