Food Ordering

In this step-by-step walkthrough, you’ll build a conversational application that allows users to order food for delivery from nearby restaurants, using the MindMeld blueprint for this purpose.


Please make sure to install and run all of the pre-requisites for MindMeld before continuing on with this blueprint tutorial.

1. The Use Case

In a hands-free manner, from the convenience of their homes, users should have the same food-ordering experience as when conversing with a restaurant waiter or a drive-through attendant. The food is ordered for delivery from a service similar to Amazon Restaurants, Grubhub or DoorDash.

2. Example Dialogue Interactions

The conversational flows for food ordering can be highly complex, depending on the desired app functionality and the amount of user guidance required at each step. Enumerating and finalizing all anticipated user interactions requires multiple iterations.

Here are some examples of scripted dialogue interactions for conversational flows.



Pick a convenient textual or graphical representation. Try to design as many user flows as you can. Always capture the entire dialogue from start to finish. Think of scenarios that differ from the examples above, such as: asking to order from a specific restaurant without choosing a dish; requesting a dish that is not available at the selected restaurant; asking for a restaurant location that doesn’t exist; choosing a customization option that is not applicable for the chosen dish, and so on.

3. Domain-Intent-Entity Hierarchy

Here is the NLP model hierarchy for our food ordering application.


The single domain, ordering, encompasses all of the functionality required to order food for delivery from nearby restaurants. The ordering domain supports the following intents:

  • greet — User wants to start a conversation
  • build_order — User wants to make selections for food delivery
  • place_order — User wants to confirm and place an order
  • start_over — User wants to abandon current selections and restart the ordering process
  • exit — User wants to end the current conversation
  • help — User is confused or needs instructions on how to proceed
  • unsupported — User is talking about something other than food ordering

For this app, only the build_order intent requires entity recognition. This intent supports the following entity types:

  • restaurant — The name of a restaurant location
  • cuisine — The name of a cuisine
  • category — The name of a food category on a restaurant menu
  • dish — The name of a dish on a restaurant menu
  • option — The name of an available option (customization, add-on, etc.) for a dish
  • sys_number — The quantity of a given dish, captured by the number system entity

The sys_number entity can play two roles (num_orders and item_size) so queries containing sys_number entities must be labeled accordingly. The num_orders role represents the number of desired orders and the item_size role represents the size of a desired item. The role annotation follows the entity annotation in the following manner: can I have a {12|sys_number|item_size} ounce burger and {one|sys_number|num_orders} {parfait|dish} please.


While the blueprint provides a good starting point, you may need additional intents and entities to support the desired scope of your app. Enumerate some other intents (e.g., check_order_status, get_calories, and so on) and entities (e.g., location, price_level, and so on) that make sense for a food ordering use case.

To train the different machine learning models in the NLP pipeline for this app, we need labeled training data that covers all our intents and entities. To download the data and code required to run this blueprint, run the command below in a directory of your choice. (If you have already completed the Quick Start for this blueprint, you should skip this step.)


This application requires Elasticsearch for the QuestionAnswerer. Please make sure that Elasticsearch is running in another shell before proceeding to setup this blueprint.

python -c "import mindmeld as mm; mm.blueprint('food_ordering');"

This should create a MindMeld project folder called food_ordering in your current directory with the following structure:


4. Dialogue States

To support the functionality we envision, our app needs one dialogue state for each intent, as shown in the table below.


Dialogue State
Dialogue State
Begin an interaction and welcome the user


Guide the user through making selections
and build up the delivery order
Place the order to complete the transaction


Cancel the ongoing transaction
and prompt the user for a new request
End the current interaction


Provide help information
in case the user gets stuck


Prompt a user who has gone off-topic
to get back to food ordering

All dialogue states and their associated handlers are defined in the application container file at the top level of the blueprint folder.

Handler logic can be simple, complex, or in between. At one end of this spectrum, the handler simply returns a canned response, sometimes choosing randomly from a set of responses. A more sophisticated handler could execute knowledge base queries to fill in the slots of a partially-templatized response. And a handler that applies more complex business logic could call an external API, process what the API returns, and incorporate the result into the response template.

The handler logic is fairly straightforward for most of our dialogue states. The main actions are choosing from a set of pre-scripted natural language responses, and replying to the user. These simple states include welcome, start_over, say_goodbye, provide_help and default.

For example, here’s the say_goodbye state handler, where we clear the dialogue frame and use the responder object to reply with one of our scripted “goodbye” responses:

def say_goodbye(request, responder):
    When the user ends a conversation, clear the dialogue frame and say goodbye.
    # Clear the dialogue frame to start afresh for the next user request.
    responder.frame = {}

    # Respond with a random selection from one of the canned "goodbye" responses.
    responder.reply(['Bye!', 'Goodbye!', 'Have a nice day.', 'See you later.'])

By contrast, the handler logic for the build_order and place_order dialogue states is more substantial, because they contain the core business logic for our application. In these dialogue state handlers, we use the Question Answerer and external API calls to process the transaction.

We can illustrate this with a simplistic implementation of the build_order handler:

def build_order(request, responder):
    When the user expresses an intent to make food selections, build up the order by
    adding the requested dishes to their "check-out" basket.
    # Get the first recognized restaurant entity in the user query.
    rest_entity = next(e for e in request.entities if e['type'] == 'restaurant')

    # Resolve the restaurant entity to a specific entry in the knowledge base (KB).
    selected_restaurant = _get_restaurant_from_kb(rest_entity['value'][0]['id'])

    # Next, get all the recognized dish entities in the user query.
    dish_entities = [e for e in request.entities if e['type'] == 'dish']

    # Add dishes one by one to the "check-out" shopping basket.
    selected_dishes = list()
    for entity in dish_entities:
        # Resolve the dish entity to a KB entry using restaurant information.
        selected_dishes.append(_resolve_dish(entity, selected_restaurant))

    # Store dish and restaurant selections in the dialogue frame.
    responder.frame['restaurant'] = selected_restaurant
    responder.frame['dishes'] = selected_dishes

    # Respond with a preview of the current basket and prompt for order confirmation.
    responder.slots['restaurant_name'] = selected_restaurant['name']
    responder.slots['dish_names'] = ', '.join([dish['name'] for dish in selected_dishes])
    responder.slots['price'] = sum([dish['price'] for dish in selected_dishes])
    responder.reply('Sure, I got {dish_names} from {restaurant_name} for a total '
                    'price of ${price:.2f}. Would you like to place the order?')

This code assumes that every user query contains a restaurant entity and at least one dish entity. Using the Question Answerer (within the _get_restaurant_from_kb() and _resolve_dish() functions not shown above), it selects the most likely restaurant and dishes requested by the user. Next, it saves this information in the dialogue frame for use in future conversational turns, and presents it to the user via the responder object.

For a more realistic implementation of build_order that deals with varied user flows and the full code behind all the dialogue state handlers, see the file in the blueprint folder.


Extend the build_order dialogue state handler in to handle more user flows or handle the existing ones in a smarter way. See the suggestions for improvements in the comments in the code. Here are a few more:

  • Make it possible to select restaurants by cuisine or to search for dishes by category. These are already modeled as entities in the blueprint and available as part of the restaurant and dish metadata stored in the knowledge base. But build_order needs some additional code to handle queries containing these entities.
  • After providing restaurant suggestions to a user based on a requested dish, do not ask the user to repeat the dish selection from scratch in the next turn. Instead, keep track of the dish the user was originally interested in. Then, when the user makes a restaurant selection, add the dish to the check-out basket.
  • Update the natural language response templates to include resolved options that are stored in the dialogue frame (responder.frame['dishes']) for each dish. Try to construct your responses such that if someone orders the same dish with different options, instead of saying ‘I have 3 orders of steak from …’ your app could respond with something like ‘I have 1 order of steak medium rare and 2 orders of steak well done from …’.

5. Knowledge Base

The knowledge base for our food ordering app leverages publicly available information about San Francisco restaurants from Amazon Restaurants. The knowledge base comprises two indexes in Elasticsearch:

  • restaurants — information about restaurant locations
  • menu_items — information about dishes on different restaurants’ menus

For example, here’s the knowledge base entry in the restaurants index for “Basa Seafood Express,” a seafood restaurant in San Francisco:

    "cuisine_types": ["Seafood", "Sushi"],
    "rating": 3.2,
    "name": "Basa Seafood Express",
    "num_reviews": 8,
    "menus": [
            "option_groups": [
                    "max_selected": 1,
                    "options": [
                            "price": 0.0,
                            "description": null,
                            "name": "Coke",
                            "id": "B01N1ME52H"
                            "price": 0.0,
                            "description": null,
                            "name": "Water",
                            "id": "B01MTUONJU"
                    "min_selected": 1,
                    "id": "Coke or Water",
                    "name": "Choose One"
            "id": "78eb0100-029d-4efc-8b8c-77f97dc875b5",
            "size_groups": [
                    "sizes": [
                            "alt_name": "Small",
                            "name": "Small"
                            "alt_name": "Medium",
                            "name": "Medium"
                    "description": null,
                    "name": "Choose Size",
                    "id": "Size"
    "image_url": "",
    "price_range": 1.0,
    "id": "B01N97KQNJ",
    "categories": ["Hawaiian Style Poke (HP)", "Ceviche (C)", "Nigiri Sushi (2 Pcs)", "Popular Dishes",
        "Makimono-Sushi Rolls (6 Pcs)", "Clam Chowder (CC)", "Side Order (SO)", "Sashimi (5 Pcs)",
        "Fish & Chips (FC)", "Salads (SL)", "Rice Bowl (RB)", "Sandwiches (SW)", "Special Rolls",
        "Special Combo (PC)"]

Here’s a knowledge base entry in the menu_items index for a dish from the above restaurant.

    "category": "Nigiri Sushi (2 Pcs)",
    "menu_id": "78eb0100-029d-4efc-8b8c-77f97dc875b5",
    "description": "Nigiri Sushi",
    "price": 4.5,
    "option_groups": [],
    "restaurant_id": "B01N97KQNJ",
    "size_prices": [],
    "size_group": null,
    "popular": false,
    "img_url": null,
    "id": "B01MTUOW2R",
    "name": "Masago (Capelin Roe)"

Assuming that you have Elasticsearch installed, running the blueprint() command described above should build the knowledge base for the food ordering app by creating the two indexes and importing all the necessary data. To verify that the knowledge base has been set up correctly, use the Question Answerer to query the indexes.


Make sure that Elasticsearch is running in a separate shell before invoking the QuestionAnswerer.

from mindmeld.components.question_answerer import QuestionAnswerer
qa = QuestionAnswerer(app_path='food_ordering')
   "size_group": "pizzasize",
   "menu_id": "57572a43-f9fc-4a1c-96fe-788d544b1f2d",
   "restaurant_id": "B01DEEGQBK",
   "size_prices": [
         "name": "12\" Small",
         "price": 13.99,
         "id": "B01N9YUFMX"
         "name": "14\" Medium",
         "price": 16.99,
         "id": "B01MRDF6V1"
         "name": "16\" Large",
         "price": 17.99,
         "id": "B01MUI0ZGE"
         "name": "18\" X-Large",
         "price": 19.99,
         "id": "B01N7ZK0ZR"
   "option_groups": [
   "img_url": null,
   "description": null,
   "id": "B01NB08SGM",
   "popular": false,
   "name": "Cheese Pizza",
   "category": "Pizzas",
   "price": 13.99


The blueprint comes with a pre-configured, pre-populated knowledge base to help you get up and running quickly. Read the User Guide section on Question Answerer to learn how to create knowledge base indexes from scratch. Then, try creating one or more knowledge base indexes for your own data.

6. Training Data

The labeled data for training our NLP pipeline was created using both in-house data generation and crowdsourcing techniques. See Step 6 of the Step-By-Step Guide for a full description of this highly important, multi-step process. Be aware that at minimum, the following data generation tasks are required:


Question (for crowdsourced data generators)
or instruction (for annotators)
Exploratory data generation
for guiding the app design
“How would you talk to a conversational app
to place orders for food?”
Targeted query generation
for training the Intent Classifier

build_order: “What would you say to the app
to make food or restaurant selections and create
your delivery order?”
Targeted query annotation
for training the Entity Recognizer

build_order: “Annotate all occurrences of restaurant,
cuisine, category, dish and option names
in the given query.”
Targeted synonym generation
for training the Entity Resolver

restaurant: “What are the different ways in which
you would refer to this restaurant location?”

dish: “What names would you use to refer
to this item on the restaurant menu?”
Annotate queries for
training the Role Classifier

sys_number: “Annotate all entities with their
corresponding roles, e.g. num_orders and item_size.”

The domains directory contains the training data for intent classification and entity recognition. The entities directory contains the data for entity resolution. Both directories are at root level in the blueprint folder.

Exercise 1

  • Study the best practices around training data generation and annotation for conversational apps in Step 6 of the Step-By-Step Guide. Following those principles, create additional labeled data for all the intents in this blueprint. Read more about NLP model evaluation and error analysis in the User Guide. Then apply what you have learned in evaluating your app, using your newly-created labeled data as held-out validation data.
  • Complete the following exercise if you are extending the blueprint to build your own food ordering app. For app-agnostic, generic intents like greet, exit, and help, start by simply reusing the blueprint data to train NLP models for your food ordering app. For build_order and any other app-specific intents, gather new training data tailored to the relevant entities (restaurants, dishes, etc.). Apply the approach you learned in Step 6.

7. Training the NLP Classifiers

Train a baseline NLP system for the blueprint app. The build() method of the NaturalLanguageProcessor class, used as shown below, applies MindMeld’s default machine learning settings.

from mindmeld.components.nlp import NaturalLanguageProcessor
import mindmeld as mm
nlp = NaturalLanguageProcessor(app_path='food_ordering')
Fitting intent classifier: domain='ordering'
Loading queries from file ordering/build_order/train.txt
Loading queries from file ordering/exit/train.txt
Loading queries from file ordering/greet/train.txt
Loading queries from file ordering/help/train.txt
Loading queries from file ordering/place_order/train.txt
Loading queries from file ordering/start_over/train.txt
Loading queries from file ordering/unsupported/train.txt
Selecting hyperparameters using k-fold cross-validation with 10 splits
Best accuracy: 98.11%, params: {'C': 100, 'class_weight': {0: 1.7987394957983194, 1: 3.0125475285171097, 2: 0.89798826487845773, 3: 4.4964705882352938, 4: 2.5018518518518515, 5: 1.7559183673469387, 6: 0.46913229018492181}, 'fit_intercept': True}
Fitting entity recognizer: domain='ordering', intent='place_order'
Fitting entity recognizer: domain='ordering', intent='unsupported'
Fitting entity recognizer: domain='ordering', intent='greet'
Fitting entity recognizer: domain='ordering', intent='exit'
Fitting entity recognizer: domain='ordering', intent='build_order'
Selecting hyperparameters using k-fold cross-validation with 5 splits
Best accuracy: 92.46%, params: {'C': 1000000, 'penalty': 'l2'}
Fitting entity recognizer: domain='ordering', intent='start_over'
Fitting entity recognizer: domain='ordering', intent='help'


During active development, it’s helpful to increase the MindMeld logging level to better understand what’s happening behind the scenes. All code snippets here assume that logging level has been set to verbose.

To see how the trained NLP pipeline performs on a test query, use the process() method.

nlp.process("I'd like a mujaddara wrap and two chicken kebab from palmyra")
{ 'domain': 'ordering',
  'entities': [ { 'role': None,
                  'span': {'end': 24, 'start': 11},
                  'text': 'mujaddara wrap',
                  'type': 'dish',
                  'value': [ { 'cname': 'Mujaddara Wrap',
                               'id': 'B01DEFNIRY',
                               'score': 169.67435,
                               'top_synonym': 'Mujaddara Wrap'},
                             { 'cname': "Veggie Lover's Wrap",
                               'id': 'B01D0QQNQA',
                               'score': 22.034618,
                               'top_synonym': 'veggie wrap'},
                             { 'cname': 'Beef Shawarma Wrap',
                               'id': 'B01DEFMQR2',
                               'score': 22.034618,
                               'top_synonym': 'beef wrap'},
                             { 'cname': 'Sahara',
                               'id': 'B01MDU5D1V',
                               'score': 21.205025,
                               'top_synonym': 'falafel wrap'},
                             { 'cname': 'Falafel Wrap',
                               'id': 'B01CRF8HUU',
                               'score': 19.44212,
                               'top_synonym': 'Falafel Wrap'},
                             { 'cname': 'Falafel Wrap',
                               'id': 'B01DEFMLMC',
                               'score': 19.44212,
                               'top_synonym': 'Falafel Wrap'},
                             { 'cname': 'Chicken Wrap',
                               'id': 'B01CK514OI',
                               'score': 19.44212,
                               'top_synonym': 'Chicken Wrap'},
                             { 'cname': 'Veggie Wrap',
                               'id': 'B01CUUBRZY',
                               'score': 19.218494,
                               'top_synonym': 'Veggie Wrap'},
                             { 'cname': 'Kebab Wrap',
                               'id': 'B01CRF8ULQ',
                               'score': 19.218494,
                               'top_synonym': 'meat wrap'},
                             { 'cname': 'Kofte Wrap',
                               'id': 'B01DEFNGEY',
                               'score': 19.218494,
                               'top_synonym': 'Kofte Wrap'}]},
                { 'role': 'num_orders',
                  'span': {'end': 32, 'start': 30},
                  'text': 'two',
                  'type': 'sys_number',
                  'value': [{'value': 2}]},
                { 'children': [ { 'role': 'num_orders',
                                  'span': {'end': 32, 'start': 30},
                                  'text': 'two',
                                  'type': 'sys_number',
                                  'value': [{'value': 2}]}],
                  'role': None,
                  'span': {'end': 46, 'start': 34},
                  'text': 'chicken kebab',
                  'type': 'dish',
                  'value': [ { 'cname': 'Chicken Kebab',
                               'id': 'B01DEFMUSW',
                               'score': 147.06445,
                               'top_synonym': 'Chicken Kebab'},
                             { 'cname': 'Chicken Tikka Kabab',
                               'id': 'B01DN5635O',
                               'score': 99.278786,
                               'top_synonym': 'chicken kebab'},
                             { 'cname': 'Chicken Kebab Plate',
                               'id': 'B01CK4ZQ7U',
                               'score': 93.68581,
                               'top_synonym': 'Chicken Kebab'},
                             { 'cname': 'Chicken Shish Kebab Plate',
                               'id': 'B01N9Z1K2O',
                               'score': 31.71228,
                               'top_synonym': 'chicken kebab plate'},
                             { 'cname': 'Kebab Wrap',
                               'id': 'B01CRF8ULQ',
                               'score': 21.39855,
                               'top_synonym': 'Kebab Wrap'},
                             { 'cname': 'Kofte Kebab',
                               'id': 'B01N4VET8U',
                               'score': 21.39855,
                               'top_synonym': 'beef kebab'},
                             { 'cname': 'Lamb Kebab',
                               'id': 'B01DEFNQIA',
                               'score': 21.39855,
                               'top_synonym': 'Lamb Kebab'},
                             { 'cname': 'Kebab Platter',
                               'id': 'B01CRF8A7U',
                               'score': 21.290503,
                               'top_synonym': 'Kebab Dish'},
                             { 'cname': 'Beef Kebab',
                               'id': 'B01DEFL75Y',
                               'score': 21.290503,
                               'top_synonym': 'Beef Kebab'},
                             { 'cname': 'Prawns Kebab',
                               'id': 'B01DEFO4ZY',
                               'score': 21.290503,
                               'top_synonym': 'Prawns Kebab'}]},
                { 'role': None,
                  'span': {'end': 59, 'start': 53},
                  'text': 'palmyra',
                  'type': 'restaurant',
                  'value': [ { 'cname': 'Palmyra',
                               'id': 'B01DEFLJIO',
                               'score': 52.51769,
                               'top_synonym': 'Palmyra'}]}],
  'intent': 'build_order',
  'text': "I'd like a mujaddara wrap and two chicken kebab from palmyra"}

For the data distributed with this blueprint, the baseline performance is already high. However, when extending the blueprint with your own custom food ordering data, you may find that the default settings may not be optimal and you could get better accuracy by individually optimizing each of the NLP components.

Start by inspecting the baseline configurations that the different classifiers use. The User Guide lists and describes the available configuration options. As an example, the code below shows how to access the model and feature extraction settings for the Intent Classifier.

ic =['ordering'].intent_classifier
 'bag-of-words': {'lengths': [1]},
 'freq': {'bins': 5},
 'in-gaz': {},
 'length': {}

You can experiment with different learning algorithms (model types), features, hyperparameters, and cross-validation settings by passing the appropriate parameters to the classifier’s fit() method. Here are a few examples.

Change the feature extraction settings to use bag of bigrams in addition to the default bag of words:

features = {
            'bag-of-words': {'lengths': [1, 2]},
            'freq': {'bins': 5},
            'in-gaz': {},
            'length': {}
Fitting intent classifier: domain='ordering'
Selecting hyperparameters using k-fold cross-validation with 10 splits
Best accuracy: 98.36%, params: {'C': 10000, 'class_weight': {0: 1.0, 1: 1.0, 2: 1.0, 3: 1.0, 4: 1.0, 5: 1.0, 6: 1.0}, 'fit_intercept': False}

Change the classification model to random forest instead of the default logistic regression:{'classifier_type': 'rforest'}, param_selection={'type': 'k-fold', 'k': 10, 'grid': {'class_bias': [0.7, 0.3, 0]}})
Fitting intent classifier: domain='ordering'
Selecting hyperparameters using k-fold cross-validation with 10 splits
Best accuracy: 94.12%, params: {'class_weight': {0: 1.0, 1: 1.0, 2: 1.0, 3: 1.0, 4: 1.0, 5: 1.0, 6: 1.0}}

You can use similar options to inspect and experiment with the Entity Recognizer and the other NLP classifiers. Finding the optimal machine learning settings is a highly iterative process involving several rounds of model training (with varying configurations), testing, and error analysis. See the User Guide for more about training, tuning, and evaluating the various MindMeld classifiers.


Experiment with different models, features, and hyperparameter selection settings to see how they affect classifier performance. Maintain a held-out validation set to evaluate your trained NLP models and analyze misclassified test instances. Then, use observations from the error analysis to inform your machine learning experimentation. See the User Guide for examples and discussion.

8. Parser Configuration

Once the NLP classification models are trained, you can configure and run the MindMeld Language Parser to link related entities into meaningful entity groups. The application configuration file,, at the top level of the blueprint folder, contains the following parser configuration:

    'dish': {
        'option': {'linking_words': {'with'}},
        'sys_number': {'max_instances': 1, 'right': False}
    'option': {
        'sys_number': {'max_instances': 1, 'right': False}

This configuration specifies that a dish entity can have a numeric quantity entity and an option entity as its attributes. An option entity, in turn, can have its own associated quantity entity. These are the head-dependent relations between the entities. The configuration also defines constraints which improve parsing accuracy by helping to eliminate potentially incorrect parse hypotheses. These constraints may include the number of allowed dependents of a certain kind, the allowed attachment directions, and so on. See the User Guide for a full list of configurable constraints.

The parser runs as the last step in the NLP pipeline. The easiest way to test it is to use the Natural Language Processor’s process() method.

query = "Two chicken kebab and a kibbi platter with a side of mujadara from palmyra"
entities = nlp.process(query)['entities']

You can then look at the children property of each entity to see its dependent entities. For example, you can verify that the numeric quantity “two” gets attached to the dish “chicken kebab”:

{'text': 'chicken kebab',
 'type': 'dish',
 'role': None,
 'value': [{'cname': 'Chicken Kebab',
   'score': 147.06445,
   'top_synonym': 'Chicken Kebab',
   'id': 'B01DEFMUSW'},
  {'cname': 'Chicken Tikka Kabab',
   'score': 99.278786,
   'top_synonym': 'chicken kebab',
   'id': 'B01DN5635O'},
  {'cname': 'Chicken Kebab Plate',
   'score': 93.68581,
   'top_synonym': 'Chicken Kebab',
   'id': 'B01CK4ZQ7U'},
  {'cname': 'Chicken Shish Kebab Plate',
   'score': 31.71228,
   'top_synonym': 'chicken kebab plate',
   'id': 'B01N9Z1K2O'},
  {'cname': 'Kebab Wrap',
   'score': 21.39855,
   'top_synonym': 'Kebab Wrap',
   'id': 'B01CRF8ULQ'},
  {'cname': 'Kofte Kebab',
   'score': 21.39855,
   'top_synonym': 'beef kebab',
   'id': 'B01N4VET8U'},
  {'cname': 'Lamb Kebab',
   'score': 21.39855,
   'top_synonym': 'Lamb Kebab',
   'id': 'B01DEFNQIA'},
  {'cname': 'Kebab Platter',
   'score': 21.290503,
   'top_synonym': 'Kebab Dish',
   'id': 'B01CRF8A7U'},
  {'cname': 'Beef Kebab',
   'score': 21.290503,
   'top_synonym': 'Beef Kebab',
   'id': 'B01DEFL75Y'},
  {'cname': 'Prawns Kebab',
   'score': 21.290503,
   'top_synonym': 'Prawns Kebab',
   'id': 'B01DEFO4ZY'}],
 'span': {'start': 4, 'end': 16},
 'children': [{'text': 'Two',
   'type': 'sys_number',
   'role': 'num_orders',
   'value': [{'value': 2}],
   'span': {'start': 0, 'end': 2}}]}

Similarly, the option “mujadara” should apply to the second dish, “kibbi platter”:

{'text': 'kibbi platter',
 'type': 'dish',
 'role': None,
 'value': [{'cname': 'Kibbi Platter',
   'score': 173.3674,
   'top_synonym': 'Kibbi Platter',
   'id': 'B01DEFLCL8'},
  {'cname': 'Kibbi',
   'score': 32.295372,
   'top_synonym': 'Kibbi',
   'id': 'B01DEFLNKS'},
  {'cname': 'Salad Platter',
   'score': 20.573273,
   'top_synonym': 'Salad Platter',
   'id': 'B01CUUCX0M'},
  {'cname': 'Beef Shawarma Platter',
   'score': 20.469078,
   'top_synonym': 'beef platter',
   'id': 'B01DEFNZ9K'},
  {'cname': 'Seafood Trio Platter',
   'score': 19.566566,
   'top_synonym': 'Seafood platter',
   'id': 'B01ENMO9Z2'},
  {'cname': 'Lamb Sawarma Platter',
   'score': 19.033337,
   'top_synonym': 'lamb wrap platter',
   'id': 'B01DEFLX3U'},
  {'cname': 'Kebab Platter',
   'score': 18.580826,
   'top_synonym': 'Kebab Platter',
   'id': 'B01CRF8A7U'},
  {'cname': 'Falafel Platter',
   'score': 18.580826,
   'top_synonym': 'Hummus platter',
   'id': 'B01DEFNGVC'},
  {'cname': 'Mixed Appetizer Platter',
   'score': 18.471098,
   'top_synonym': 'appetizer platter',
   'id': 'B01MYFKR8J'},
  {'cname': 'Meza Appetizer Plate',
   'score': 18.099669,
   'top_synonym': 'app platter with a pita',
   'id': 'B01CK4ZK6M'}],
 'span': {'start': 24, 'end': 36},
 'children': [{'text': 'mujadara',
   'type': 'option',
   'role': None,
   'value': [{'cname': 'Mujadara',
     'score': 127.824684,
     'top_synonym': 'Mujadara',
     'id': 'B01DEFLSN0'},
    {'cname': 'Marinara',
     'score': 13.329033,
     'top_synonym': 'Marinara',
     'id': 'B01ENMOGXW'},
    {'cname': 'Marinara',
     'score': 12.622546,
     'top_synonym': 'Marinara',
     'id': 'B01ENTRJNO'},
    {'cname': 'Cheddar',
     'score': 12.622546,
     'top_synonym': 'Cheddar',
     'id': 'B01CH0S4MG'},
    {'cname': 'Cheddar',
     'score': 12.622546,
     'top_synonym': 'Cheddar',
     'id': 'B01MRRXEW5'},
    {'cname': 'Caramelized Onions',
     'score': 12.330592,
     'top_synonym': 'Caramelized Onions',
     'id': 'B01MXSPQLC'},
    {'cname': 'Cheddar Cheese',
     'score': 12.330592,
     'top_synonym': 'Cheddar Cheese',
     'id': 'B01N59TWZ1'},
    {'cname': 'Cheddar',
     'score': 11.7442465,
     'top_synonym': 'Cheddar',
     'id': 'B01M7XF00X'},
    {'cname': 'Cheddar',
     'score': 11.7442465,
     'top_synonym': 'Cheddar',
     'id': 'B01CH0SM7S'},
    {'cname': 'Cheddar Cheese',
     'score': 11.689834,
     'top_synonym': 'Cheddar Cheese',
     'id': 'B01CH0RY9K'}],
   'span': {'start': 53, 'end': 60}}]

Lastly, the restaurant “Palmyra” is a standalone entity without any dependents and hence has no children:

{'text': 'palmyra',
 'type': 'restaurant',
 'role': None,
 'value': [{'cname': 'Palmyra',
   'score': 52.51769,
   'top_synonym': 'Palmyra',
   'id': 'B01DEFLJIO'}],
 'span': {'start': 67, 'end': 73}

When extending the blueprint to your custom application data, the parser should work fine out-of-the-box for most queries, provided that head-dependent relations are properly set in the configuration file. To improve its accuracy further, experiment with the parser constraints, optimizing them for what makes the best sense for your data. See the Language Parser section of the User Guide for details.


  • Experiment with the different constraints in the parser configuration and observe how it affects parsing accuracy.
  • Think of any additional entity relationships you might want to capture when extending the blueprint with new entity types for your own use case. For instance, the blueprint treats restaurant as a standalone entity. However, you might want to introduce related entities like location (to search for restaurants by geographical area or address) or price_level (the number of “dollar signs” or average price per person at a restaurant). In that case, you would need to update the parser configuration to extract these new relations.

9. Using the Question Answerer

The Question Answerer component in MindMeld is mainly used within dialogue state handlers for retrieving information from the knowledge base. For example, in our welcome dialogue state handler, we use the Question Answerer to retrieve the top three entries in our restaurants index and present their names as suggestions to the user.

from mindmeld.components.question_answerer import QuestionAnswerer
qa = QuestionAnswerer(app_path='food_ordering')
restaurants = qa.get(index='restaurants')[0:3]
[restaurant['name'] for restaurant in restaurants]
 "Firetrail Pizza",
 "Grandma's Deli & Cafe",
 "The Salad Place"

The build_order handler retrieves details about the user’s restaurant and dish selections from the knowledge base, and uses the information to

  1. Suggest restaurants to the user that offer their requested dishes
  2. Resolve the requested dish name to the most likely entry on a restaurant’s menu
  3. Verify that a requested dish is offered at the selected restaurant
  4. Verify that a requested option is applicable for the selected dish
  5. Get pricing for the requested dish and options

Look at the build_order implementation in to better understand the different ways you can leverage the knowledge base and Question Answerer to provide intelligent responses to the user. See the User Guide for an explanation of the retrieval and ranking mechanisms that the Question Answerer offers.


  • Use the Question Answerer within the build_order state handler to add support for searching for restaurants by cuisine and searching for dishes by category.
  • When customizing the blueprint for your own app, consider adding location information (for restaurants) and popularity (for both restaurants and dishes) in the knowledge base. You could then use the Question Answerer to rank restaurant and dish results using those factors, and evaluate whether this provides a more relevant list of suggestions to the user.
  • Think of other important data that would be useful to have in the knowledge base for a food ordering use case. Identify the ways that data could be leveraged to provide a more intelligent user experience.

10. Testing and Deployment

Once all the individual pieces (NLP, Question Answererer, Dialogue State Handlers) have been trained, configured, or implemented, use the Conversation class in MindMeld to perform an end-to-end test of your conversational app.

For instance:

from mindmeld.components.dialogue import Conversation
conv = Conversation(nlp=nlp, app_path='food_ordering')
conv.say("Get me a pad thai and pinapple fried rice from thep phanom thai")
['Sure, I have 1 order of 62. Pad Thai and 1 order of 66. Pineapple Fried Rice from Thep Phanom Thai Restaurant for a total price of $34.00. Would you like to place the order?']

The say() method packages the input text in a user request object and passes it to the MindMeld Application Manager to simulate a user interacting with the application. The method then outputs the textual part of the response sent by the app’s Dialogue Manager. In the above example, we requested dishes from a restaurant, in a single query. The app responded, as expected, with a preview of the order details and a confirmation prompt.

You can also try out multi-turn dialogues:

>>> conv = Conversation(nlp=nlp, app_path='food_ordering')
>>> conv.say('Hi there!')
['Hello. Some nearby popular restaurants you can order delivery from are Firetrail Pizza, Grandma's Deli & Cafe, The Salad Place']
>>> conv.say("I'd like to order from Saffron 685 today")
['Great, what would you like to order from Saffron 685?', 'Listening...']
>>> conv.say("I would like two dolmas and a meza appetizer plate")
['Sure, I got 2 Dolmas, 1 Meza Appetizer Plate from Saffron 685 for a total price of $18.75. Would you like to place the order?', 'Listening...']
>>> conv.say("I almost forgot! Could you also add a baklava please?")
['Sure, I got 2 Dolmas, 1 Meza Appetizer Plate, 1 Baklava from Saffron 685 for a total price of $22. Would you like to place the order?', 'Listening...']
>>> conv.say("Yes")
['Great, your order from Saffron 685 will be delivered in 30-45 minutes.']
>>> conv.say("Thank you!")
['Have a nice day.']


Test the app multiple times with different conversational flows. Keep track of all cases where the response does not make good sense. Then, analyze those cases in detail. You should be able to attribute each error to a specific step in our end-to-end processing (e.g., incorrect intent classification, missed entity recognition, unideal natural language response, and so on). Categorizing your errors in this manner helps you understand the strength of each component in your conversational AI pipeline and informs you about the possible next steps for improving the performance of each individual module.

Refer to the User Guide for tips and best practices on testing your app before launch.