diff --git a/client/app/components/dynamic-form/DynamicForm.jsx b/client/app/components/dynamic-form/DynamicForm.jsx
index b0ab61b1b0..b41b5630f9 100644
--- a/client/app/components/dynamic-form/DynamicForm.jsx
+++ b/client/app/components/dynamic-form/DynamicForm.jsx
@@ -7,21 +7,37 @@ import Checkbox from 'antd/lib/checkbox';
 import Button from 'antd/lib/button';
 import Upload from 'antd/lib/upload';
 import Icon from 'antd/lib/icon';
-import { includes, isFunction } from 'lodash';
+import { includes, isFunction, isPlainObject, isArray } from 'lodash';
 import Select from 'antd/lib/select';
 import notification from '@/services/notification';
 import { Field, Action, AntdForm } from '../proptypes';
 import helper from './dynamicFormHelper';
 
+const { TextArea } = Input;
+
 const fieldRules = ({ type, required, minLength }) => {
   const requiredRule = required;
   const minLengthRule = minLength && includes(['text', 'email', 'password'], type);
   const emailTypeRule = type === 'email';
+  const jsonRule = type === 'json';
 
   return [
     requiredRule && { required, message: 'This field is required.' },
     minLengthRule && { min: minLength, message: 'This field is too short.' },
     emailTypeRule && { type: 'email', message: 'This field must be a valid email.' },
+    jsonRule && {
+      type: 'object',
+      transform(x) {
+        if (x.trim()) {
+          try {
+            JSON.parse(x);
+          } catch {
+            return '';
+          }
+        }
+      },
+      message: 'This field must be a JSON string.',
+    },
   ].filter(rule => rule);
 };
 
@@ -74,13 +90,22 @@ class DynamicForm extends React.Component {
     }));
   };
 
+  parseValues = (values) => {
+    this.props.fields.forEach((field) => {
+      if (field.type === 'json' && field.name in values) {
+        values[field.name] = JSON.parse(values[field.name]);
+      }
+    });
+    return values;
+  };
+
   handleSubmit = (e) => {
     this.setState({ isSubmitting: true });
     e.preventDefault();
     this.props.form.validateFieldsAndScroll((err, values) => {
       if (!err) {
         this.props.onSubmit(
-          values,
+          this.parseValues(values),
           (msg) => {
             const { setFieldsValue, getFieldsValue } = this.props.form;
             this.setState({ isSubmitting: false });
@@ -155,8 +180,13 @@ class DynamicForm extends React.Component {
 
   renderField(field, props) {
     const { getFieldDecorator } = this.props.form;
-    const { name, type, initialValue } = field;
+    const { name, type } = field;
     const fieldLabel = field.title || helper.toHuman(name);
+    let initialValue = field.initialValue;
+
+    if (isPlainObject(initialValue) || isArray(initialValue)) {
+      initialValue = JSON.stringify(field.initialValue);
+    }
 
     const options = {
       rules: fieldRules(field),
@@ -174,6 +204,8 @@ class DynamicForm extends React.Component {
       return field.content;
     } else if (type === 'number') {
       return getFieldDecorator(name, options)(<InputNumber {...props} />);
+    } else if (type === 'json') {
+      return getFieldDecorator(name, options)(<TextArea {...props} />);
     }
     return getFieldDecorator(name, options)(<Input {...props} />);
   }
@@ -185,12 +217,6 @@ class DynamicForm extends React.Component {
       const fieldLabel = title || helper.toHuman(name);
       const { feedbackIcons, form } = this.props;
 
-      const formItemProps = {
-        className: 'm-b-10',
-        hasFeedback: type !== 'checkbox' && type !== 'file' && feedbackIcons,
-        label: type === 'checkbox' ? '' : fieldLabel,
-      };
-
       const fieldProps = {
         ...field.props,
         className: 'w-100',
@@ -201,6 +227,12 @@ class DynamicForm extends React.Component {
         placeholder: field.placeholder,
         'data-test': fieldLabel,
       };
+      const formItemProps = {
+        className: 'm-b-10',
+        hasFeedback: type !== 'checkbox' && type !== 'file' && feedbackIcons,
+        label: type === 'checkbox' ? '' : fieldLabel,
+        extra: fieldProps.extra,
+      };
 
       return (
         <React.Fragment key={name}>
diff --git a/client/app/components/dynamic-form/dynamicFormHelper.js b/client/app/components/dynamic-form/dynamicFormHelper.js
index c1d17997d3..f917e3ba6c 100644
--- a/client/app/components/dynamic-form/dynamicFormHelper.js
+++ b/client/app/components/dynamic-form/dynamicFormHelper.js
@@ -5,13 +5,15 @@ function orderedInputs(properties, order, targetOptions) {
   const inputs = new Array(order.length);
   Object.keys(properties).forEach((key) => {
     const position = order.indexOf(key);
+    const field = properties[key];
     const input = {
       name: key,
-      title: properties[key].title,
-      type: properties[key].type,
-      placeholder: properties[key].default && properties[key].default.toString(),
-      required: properties[key].required,
+      title: field.title,
+      type: field.type,
+      placeholder: field.default && field.default.toString(),
+      required: field.required,
       initialValue: targetOptions[key],
+      props: field.props,
     };
 
     if (position > -1) {
@@ -41,6 +43,10 @@ function normalizeSchema(configurationSchema) {
       prop.type = 'text';
     }
 
+    if (prop.type === 'object') {
+      prop.type = 'json';
+    }
+
     prop.required = includes(configurationSchema.required, name);
   });
 
diff --git a/client/app/components/proptypes.js b/client/app/components/proptypes.js
index 05b585904d..3af06b5c69 100644
--- a/client/app/components/proptypes.js
+++ b/client/app/components/proptypes.js
@@ -43,11 +43,13 @@ export const Field = PropTypes.shape({
     'file',
     'select',
     'content',
+    'json',
   ]).isRequired,
   initialValue: PropTypes.oneOfType([
     PropTypes.string,
     PropTypes.number,
     PropTypes.bool,
+    PropTypes.object,
     PropTypes.arrayOf(PropTypes.string),
     PropTypes.arrayOf(PropTypes.number),
   ]),
diff --git a/redash/handlers/data_sources.py b/redash/handlers/data_sources.py
index 0d814a0209..13302f7055 100644
--- a/redash/handlers/data_sources.py
+++ b/redash/handlers/data_sources.py
@@ -45,7 +45,7 @@ def post(self, data_source_id):
         try:
             data_source.options.set_schema(schema)
             data_source.options.update(filter_none(req['options']))
-        except ValidationError:
+        except ValidationError, e:
             abort(400)
 
         data_source.type = req['type']
diff --git a/redash/query_runner/presto.py b/redash/query_runner/presto.py
index 2966d1ccf9..82ad821436 100644
--- a/redash/query_runner/presto.py
+++ b/redash/query_runner/presto.py
@@ -59,8 +59,17 @@ def configuration_schema(cls):
                 'password': {
                     'type': 'string'
                 },
+                'extras': {
+                    'type': 'object',
+                    'default': '{ "requests_kwargs": null }',
+                    'props': {
+                        'rows': 2,
+                        'extra': 'Extra kwargs passed to presto.connect(...)',
+                    }
+                }
             },
-            'order': ['host', 'protocol', 'port', 'username', 'password', 'schema', 'catalog'],
+            'order': ['host', 'protocol', 'port', 'username', 'password',
+                      'schema', 'catalog', 'extras'],
             'required': ['host']
         }
 
@@ -105,7 +114,8 @@ def run_query(self, query, user):
             username=self.configuration.get('username', 'redash'),
             password=(self.configuration.get('password') or None),
             catalog=self.configuration.get('catalog', 'hive'),
-            schema=self.configuration.get('schema', 'default'))
+            schema=self.configuration.get('schema', 'default'),
+            **self.configuration.get('extras', {}))
 
         cursor = connection.cursor()