columnInfo, adapted code from @johanneslumpe in #190

lib/client.js

@@ -45,4 +45,9 @@ Client.prototype.releaseConnection = function(connection) {
   });
 };
 
+// Return the database being used by this client.
+Client.prototype.database = function() {
+  return this.connectionSettings.database;
+};
+
 module.exports = Client;

lib/dialects/mysql/query.js

@@ -2,6 +2,7 @@
 // ------
 module.exports = function(client) {
 
+var _             = require('lodash');
 var inherits      = require('inherits');
 var QueryBuilder  = require('../../query/builder');
 var QueryCompiler = require('../../query/compiler');
@@ -53,6 +54,24 @@ QueryCompiler_MySQL.prototype.forShare = function() {
   return 'lock in share mode';
 };
 
+// Compiles a `columnInfo` query.
+QueryCompiler_MySQL.prototype.columnInfo = function() {
+  return {
+    sql: 'select column_name, data_type, character_maximum_length ' +
+      'from information_schema.columns where table_name = ? and table_schema = ?',
+    bindings: [this.single.table, client.database()],
+    output: function(resp) {
+      return _.reduce(resp, function(columns, val) {
+        columns[val.column_name] = {
+          type: val.data_type,
+          length: val.character_maximum_length
+        };
+        return columns;
+      }, {});
+    }
+  };
+};
+
 // Set the QueryBuilder & QueryCompiler on the client object,
 // incase anyone wants to modify things to suit their own purposes.
 client.QueryBuilder  = QueryBuilder_MySQL;

lib/dialects/postgres/query.js

@@ -2,6 +2,7 @@
 // ------
 module.exports = function(client) {
 
+var _        = require('lodash');
 var inherits = require('inherits');
 
 var QueryBuilder  = require('../../query/builder');
@@ -78,6 +79,24 @@ QueryCompiler_PG.prototype.forShare = function() {
   return 'for share';
 };
 
+// Compiles a columnInfo query
+QueryCompiler_PG.prototype.columnInfo = function() {
+  return {
+    sql: 'select column_name, data_type, character_maximum_length from information_schema.columns' +
+      ' where table_name = ? and table_catalog = ?',
+    bindings: [this.single.table, client.database()],
+    output: function(resp) {
+      return _.reduce(resp.rows, function (columns, val) {
+        columns[val.column_name] = {
+          type: val.data_type,
+          length: val.character_maximum_length
+        };
+        return columns;
+      }, {});
+    }
+  };
+};
+
 client.QueryBuilder = QueryBuilder_PG;
 client.QueryCompiler = QueryCompiler_PG;
 

lib/dialects/sqlite3/query.js

@@ -86,6 +86,26 @@ QueryCompiler_SQLite3.prototype.truncate = function() {
   };
 };
 
+// Compiles a `columnInfo` query
+QueryCompiler_SQLite3.prototype.columnInfo = function() {
+  return {
+    sql: 'PRAGMA table_info(' + this.single.table +')',
+    output: function(resp) {
+      var maxLengthRegex = /.*\((\d+)\)/;
+      return _.reduce(resp, function (columns, val) {
+        var type = val.type;
+        var maxLength = (maxLength = type.match(maxLengthRegex)) && maxLength[1];
+        type = maxLength ? type.split('(')[0] : type;
+        columns[val.name] = {
+          type: type.toLowerCase(),
+          length: maxLength
+        };
+        return columns;
+      }, {});
+    }
+  };
+};
+
 client.QueryBuilder = QueryBuilder_SQLite3;
 client.QueryCompiler = QueryCompiler_SQLite3;
 

lib/query/builder.js

@@ -589,6 +589,12 @@ QueryBuilder.prototype.truncate = function() {
   return this;
 };
 
+// Retrieves columns for the table specified by `knex(tableName)`
+QueryBuilder.prototype.columnInfo = function() {
+  this._method = 'columnInfo';
+  return this;
+};
+
 // Set a lock for update constraint.
 QueryBuilder.prototype.forUpdate = function() {
   this._single.lock = 'forUpdate';

lib/query/compiler.js

@@ -13,8 +13,8 @@ var QueryCompiler = function(queryBuilder) {
   this.options     = queryBuilder._options;
   this.single      = queryBuilder._single;
   this.transacting = queryBuilder._transacting;
-  this.grouped   = _.groupBy(queryBuilder._statements, 'grouping');
-  this.tableName = this.single.table ? this.formatter.wrap(this.single.table) : '';
+  this.grouped     = _.groupBy(queryBuilder._statements, 'grouping');
+  this.tableName   = this.single.table ? this.formatter.wrap(this.single.table) : '';
 };
 
 // Collapse the builder into a single object

test/integration/builder/additional.js

@@ -26,23 +26,57 @@ module.exports = function(knex) {
     });
 
     it('should allow raw queries directly with `knex.raw`', function() {
-
       var tables = {
         mysql: 'SHOW TABLES',
         postgresql: "SELECT table_name FROM information_schema.tables WHERE table_schema='public'",
         sqlite3: "SELECT name FROM sqlite_master WHERE type='table';"
       };
-
       return knex.raw(tables[knex.client.dialect]).testSql(function(tester) {
         tester(knex.client.dialect, tables[knex.client.dialect]);
       });
-
     });
 
     it('should allow using the primary table as a raw statement', function() {
-
       expect(knex(knex.raw("raw_table_name")).toQuery()).to.equal('select * from raw_table_name');
+    });
 
+    it('gets the columnInfo', function() {
+      return knex('datatype_test').columnInfo().testSql(function(tester) {
+        tester('mysql',
+          'select column_name, data_type, character_maximum_length from information_schema.columns where table_name = ? and table_schema = ?',
+          [ 'datatype_test', 'db_test' ], {
+            "enum_value": {
+              "length": 1,
+              "type": "enum"
+            },
+            "uuid": {
+              "length": 36,
+              "type": "char"
+            }
+          });
+        tester('postgresql', 'select column_name, data_type, character_maximum_length from information_schema.columns where table_name = ? and table_catalog = ?',
+        [ 'datatype_test', 'db_test' ],
+        {
+          "enum_value": {
+            "length": null,
+            "type": "text"
+          },
+          "uuid": {
+            "length": null,
+            "type": "uuid"
+          }
+        });
+        tester('sqlite3', 'PRAGMA table_info(datatype_test)', [], {
+          "enum_value": {
+            "length": null,
+            "type": "varchar"
+          },
+          "uuid": {
+            "length": "36",
+            "type": "char"
+          }
+        });
+      });
     });
 
     it('should allow renaming a column', function() {

test/unit/query/builder.js

@@ -62,13 +62,13 @@ module.exports = function(pgclient, mysqlclient, sqlite3client) {
     });
 
     it("raw wheres", function() {
-      chain = sql().select('*').from('users').whereRaw('id = ? or email = ?', [1, 'foo']).toSQL();
+      chain = sql().select('*').from('users').where(raw('id = ? or email = ?', [1, 'foo'])).toSQL();
       expect(chain.sql).to.equal('select * from "users" where id = ? or email = ?');
       expect(chain.bindings).to.eql([1, 'foo']);
     });
 
     it("raw or wheres", function() {
-      chain = sql().select('*').from('users').where('id', '=', 1).orWhereRaw('email = ?', ['foo']).toSQL();
+      chain = sql().select('*').from('users').where('id', '=', 1).orWhere(raw('email = ?', ['foo'])).toSQL();
       expect(chain.sql).to.equal('select * from "users" where "id" = ? or email = ?');
       expect(chain.bindings).to.eql([1, 'foo']);
     });