How to add custom fields to models

Plugin Extras
1

This is a collection of education plugins that demonstrate how to add a custom field to different models in Discourse. They are intended as learning tools for those looking to learn how to build discourse plugins.

GitHub-Mark How to add a custom field to a topic
GitHub-Mark How to add a custom field to a category

Who they’re for

These plugins are for people looking to learn more about creating Discourse plugins. Before you start working with these plugins, you should complete the beginners guide to creating discourse plugins.

You could use these plugins just to add custom fields on your Discourse instance, however you would still need to change the code slightly to do so. It’s not designed for plugin-and-play use on a live server.

How they work

As well as containing working code, each plugin contains a step-by-step description of what the code is doing in the form of comments. For example

## 
# type:        step
# number:      1
# title:       Register the field
# description: Where we tell discourse what kind of field we're adding.
#              You can register a string, integer, boolean or json field.
# references:  lib/plugins/instance.rb,
#              app/models/concerns/has_custom_fields.rb
##
register_topic_custom_field_type(FIELD_NAME, FIELD_TYPE.to_sym)

Hopefully the steps and comments are self explanatory. The references are there to show you where to look if you want to learn more.

Let me know if you find it useful, if something isn’t working, or the notes are unclear :slight_smile:

26 Likes
2

Thank for build plugin cho our,
i have this error later install plugin:

Oops
The software powering this discussion forum encountered an unexpected problem. We apologize for the inconvenience.
Detailed information about the error was logged, and an automatic notification generated. We’ll take a look at it.
No further action is necessary. However, if the error condition persists, you can provide additional detail, including steps to reproduce the error, by posting a discussion topic in the site’s feedback category.

3

Hey, are you running this in your local development environment? If so, could you PM your development logs? If your dev environment is set up correctly, this plugin will work.

1 Like
4

I read, but i can’t catch it. Can you spending time make a video tutorial install this plugin from make local development environment to step by step add a custom field …
So difficult to access this plugin.
If possible, can you upgrade search feature for field type is number?

image
image3056×534 62.2 KB

I can donate for this plugin, please support help me!

5

This resource that @angus has put together is even more helpful than I first realized.

Not only is the code for adding a custom field there with clear explanations, but a lot of it can be plugged directly into any plugin, because the code mostly uses variables like FIELD_NAME and FIELD_VALUE, which you can define in plugin/config/settings.yml (you also need to make sure that your plugin file structure is the same as in the github code @angus has provided). Going through the code has also given me a greater understanding of some discourse functions and methods I have seen before, but never really understood until now.

So far, the code works great to create and save topic custom fields. There are two questions that have been coming up for me:

  1. Topic List Error: It seems to throw an error in the case I try to load a category list (ie, a topic list for a category) where there are topics created prior to adding the custom field. It shows the exception page, and lists this error:
    Attempting to access a non preloaded custom field, this is disallowed to prevent N+1 queries. What’s the recommended way to solve this one?

  2. Is there a way for me to apply the custom field only for topics in certain categories? So, let’s say I have Category 1, Category 2, and Category 3, and I only want the custom field input to show up and only want the field to be saved if the topic is part of Category 3. Is there a way to do that?

1 Like
6

We (Pavilion) will be doing something like that in the future, but for now it’s just the code and the steps. If you’re stuck on a specific issue, create a post in dev and describe the issue in some detail.

I’ve added a sub-step to the topic custom fields plugin demonstrating how to preload fields if you’re using them in the topic list.

You’ll need a category custom field to identify categories it should be displayed in. I’ve given category custom fields the same treatment in this plugin, complete with the same step-by-step instructions:

Combining these two education plugins won’t take you all the way to your goal, but see if you can make it from there.

2 Likes
7

That is fantastic, @angus. Thank you very much.

A video is always nice–I’m all for making things as straightforward as possible, but I don’t think it’s required to get the key value from these resources that @angus has put together. These resources give the code that you need to accomplish the specific goal the resource is about (having a working topic custom field or a category custom field). A video would probably just be @angus or someone else talking through how to implement the resource, but that is straightforward, and we can probably just lay it out here.

To be clear, these resources are not plugins that you just add to your site as a plug and play that customizes your forum. Rather, they efficiently give you the understanding you need to code your own custom fields in your plugin.

This is how I’ve used these resources:

You will need to add in the name and type of field that you want in config/settings. The code in these resources uses variables that are defined there. So you actually don’t need to do much customizing of the code to get it to work in your own plugin after that–the variables in plugin.rb and elsewhere refer to config/settings, and then should work.

After updating config/settings, you can just follow along with the code, adding it to your plugin:

  • Start with the code in plugin.rb, and add that to your own plugin’s plugin.rb in order to create the custom field

  • Then go to the initializer (at assets/javascripts/discourse/[custom-field-initiliazer]) to get the code that will initialize the custom field and allow you to save it to the server

  • Then create the form in the view layer that will be where the user (or your app, if the app adds the field automatically) can enter the value for the custom field, here (assets/discourse/connectors/[plugin-outlet-name]/[your special template].hbs.

  • @angus has set these up so you would add the forms for the custom fields in a plugin outlet that will be inserted in the discourse template. Settings for this form are here, (assets/javascripts/discourse/lib/[custom-field-name].js.es6, so you probably want to customize that too to make the form work.

@angus feel free to correct anything I’ve said here.

Once I got the feel for setting up the custom field by going through the steps above, I then started customizing things a bit further (for example, getting more creative with how the form works), but this was an extremely helpful starting point that saved me hours of work.

After going through it, I did have some questions (like I asked earlier), but getting responses in dev seems like the most helpful way to go about things from there.

3 Likes
8

Great description! Yup, that’s how they’re intended to be used :+1:

1 Like
10

Edit: I originally posted my question regarding how to retrieve items based on a custom field here, but decided the question was sufficiently different to warrant its own post. So I posted separately here.

2 Likes
11

I’m experiencing strange behavior with the composer following the topic custom fields example.

When I hit the “create topic” button (for example, on the category show page–but anywhere on the site), the composer fails to open, and I get this error:

Uncaught Error: Assertion Failed: The key provided to set must be a string or number, you passed undefined
    at assert (index.js:172)
    at set (index.js:2802)
    at Class.set (observable.js:176)
    at composer.js:769
    at Array.forEach (<anonymous>)
    at Class.open (composer.js:768)
    at composer.js:898
    at invokeCallback (rsvp.js:493)
    at rsvp.js:558
    at rsvp.js:19

I first started seeing this error when I tried to add a new ‘create topic’ button on a new page, but since then, even I remove that new button and even if I remove any related code, the error persists.

In some way, I think the following code–from the topic-custom-field-initializer–is causing the problem:

api.serializeOnCreate(fieldName);
api.serializeToDraft(fieldName);
api.serializeToTopic(fieldName, `topic.${fieldName}`);

When I remove this code, the create topic buttons work again (properly opening the composer). When I put the code back in, the composer error comes back.

I have had this code in my plugin previously without problem. But now it causes the composer error (even if I have removed any composer or create-topic button -related code in my plugin).

Of course, this code is important–it serializes the custom field. But it seems that it is conflicting with composer. Any ideas on how to fix?

12

I was able to figure out the cause–I was trying to add two separate custom fields to the topic custom fields initializer. For some reason that was causing some interference. There probably is a way to properly add two custom fields to that file, but my code, just repeating the same code for two separate custom fields, was causing problems. It worked again fine when I removed the second custom field from that file.

13

With this skeleton code, if I wanted to add multiple fields, would each field have to be a standalone plugin?

14

I’m really excited to have found this tutorial and I’m wondering, how much, if any, tweaking would I need to do to these templates to have them work for custom user fields?

15

No, you just need to add in additional code for the additional field. In most cases by just duplicating the existing code, e.g.

add_preloaded_topic_list_custom_field(FIELD_NAME_1)
add_preloaded_topic_list_custom_field(FIELD_NAME_2)

The first place to look for custom user fields is /admin/customize/user_fields which gives you a UI to add them. If you want to have more granular control, the process looks very similar to topic and category, but you don’t actually need the frontend elements with user fields.

Actually we’re (Pavilion) thinking of making a custom fields plugin (analgous to ACF for wordpress) which would initially look a bit like the custom fields admin interface in the Custom Wizard plugin.

Screen Shot 2022-01-07 at 9.58.52 AM
Screen Shot 2022-01-07 at 9.58.52 AM2262×854 88.7 KB

Actually, some people already use the Custom Wizard plugin as a custom field manager. It lists all custom fields on your instance (from any source) and lets you add a field of any type to any model that supports them.

It doesn’t add in frontend support, e.g. like that show in the Topic Custom Field educational plugin (and that wouldn’t work in the context of the custom wizard plugin), which is why we’re thinking of breaking that out into a seperate plugin.

2 Likes
16

@angus, I think I would love this.

Especially if it adds the front-end support.

I would love to have an easy way for admins to add custom fields to different classes, allow users to fill them in (eg, to topics, posts, user profiles), and have a way for the front-end to show them.

The main thing I can’t get with the current custom user fields is a variety of field types. Right now it’s limited to 4 I think, and I’d love to have the options that are available with the Custom Wizards plugin.

Ideally, I want to build a pretty advanced searchable/filterable/sortable user directory with lots of custom fields of many types, I’ll experiment with Custom Wizards to see if it’ll work for now and hope that y’all do invest in the Custom Fields plugin.

Thanks!

17

@angus

First off, thank you so much for this plugin.

Do you possibly have a working example of this plugin (custom field to topic) to account for multiple custom fields? I was able to successfully add one custom field and made a couple modifications without a problem.

I’ve tried duplicating the code, modifying and adding an additional plugin, etc…

Does anyone have a code repo or example they are willing to share with me? Any help would be greatly appreciated.

1 Like
18

Hey @Joe_Stanton,

I’ve done it a couple times, and the way I’ve done it was to store the custom fields in an array with an object with a name and type for the custom field.

For example:

fields = [
  { name: 'isClassifiedListing', type: 'boolean' },
  { name: 'listingStatus', type: 'string' },
  { name: "listingDetails", type: 'json' }
]

Then I loop through the fields to apply the logic that’s mentioned in the this topic. You can see an example of it used in a plugin I’m working on here. However, the relevant code is below.

Example

In the server side:

  # Custom Field Registration
  fields.each do |field|
    # Register the fields
    register_topic_custom_field_type(field[:name], field[:type].to_sym)

    # Getter Methods
    add_to_class(:topic, field[:name].to_sym) do
      if !custom_fields[field[:name]].nil?
        custom_fields[field[:name]]
      else
        nil
      end
    end

    # Setter Methods
    add_to_class(:topic, "#{field[:name]}=") do |value|
      custom_fields[field[:name]] = value
    end

    # Update on Topic Creation
    on(:topic_created) do |topic, opts, user|
      topic.send("#{field[:name]}=".to_sym, opts[field[:name].to_sym])
      topic.save!
    end

    # Update on Topic Edit
    PostRevisor.track_topic_field(field[:name].to_sym) do |tc, value|
      tc.record_change(field[:name], tc.topic.send(field[:name]), value)
      tc.topic.send("#{field[:name]}=".to_sym, value.present? ? value : nil)
    end

    # Serialize to Topic
    add_to_serializer(:topic_view, field[:name].to_sym) do
      object.topic.send(field[:name])
    end

    # Preload the Fields
    add_preloaded_topic_list_custom_field(field[:name])

    # Serialize to the topic list
    add_to_serializer(:topic_list_item, field[:name].to_sym) do
      object.send(field[:name])
    end
  end

Similarly on the client side to serialize the fields:


 const CUSTOM_FIELDS = [
  { name: "isClassifiedListing", type: "boolean" },
  { name: "listingStatus", type: "string" },
  { name: "listingDetails", type: "json" },
];

  // Serialize Custom Fields:
  CUSTOM_FIELDS.forEach((field) => {
    api.serializeOnCreate(field.name);
    api.serializeToDraft(field.name);
    api.serializeToTopic(field.name, `topic.${field.name}`);
  });
2 Likes
19

Thanks @keegan !

I think I got the plugin.rb file setup correctly, the loop looks correct.

However, I’m struggling on the topic-custom-field-initializer.js file. Here is my code for both files. Any pointers for the initializer.js file? I think I’m really close here, when creating a new topic, I am getting 1/3 fields, the listingDetails field but still missing the isClassifiedListing and listingStatus

enabled_site_setting :topic_custom_field_enabled
register_asset 'stylesheets/common.scss'

after_initialize do
  fields = [
  { name: 'isClassifiedListing', type: 'boolean' },
  { name: 'listingStatus', type: 'string' },
  { name: "listingDetails", type: 'json' }
]

 fields.each do |field|

  register_topic_custom_field_type(field[:name], field[:type].to_sym)

   add_to_class(:topic, field[:name].to_sym) do
      if !custom_fields[field[:name]].nil?
        custom_fields[field[:name]]
      else
        nil
      end
    end

   add_to_class(:topic, "#{field[:name]}=") do |value|
      custom_fields[field[:name]] = value
   end

   on(:topic_created) do |topic, opts, user|
      topic.send("#{field[:name]}=".to_sym, opts[field[:name].to_sym])
      topic.save!
   end

    PostRevisor.track_topic_field(field[:name].to_sym) do |tc, value|
      tc.record_change(field[:name], tc.topic.send(field[:name]), value)
      tc.topic.send("#{field[:name]}=".to_sym, value.present? ? value : nil)
    end

    add_to_serializer(:topic_view, field[:name].to_sym) do
      object.topic.send(field[:name])
    end

  add_preloaded_topic_list_custom_field(field[:name])

    # Serialize to the topic list
    add_to_serializer(:topic_list_item, field[:name].to_sym) do
      object.send(field[:name])
    end

end

end

Initializer.js

import { withPluginApi } from 'discourse/lib/plugin-api';
import discourseComputed from "discourse-common/utils/decorators";
import { alias } from '@ember/object/computed';
import { isDefined, fieldInputTypes } from '../lib/topic-custom-field';

export default {
  name: "topic-custom-field-intializer",
  initialize(container) {


    const CUSTOM_FIELDS = [
      { name: "isClassifiedListing", type: "boolean" },
      { name: "listingStatus", type: "string" },
      { name: "listingDetails", type: "json" },
    ];

    CUSTOM_FIELDS.forEach((field) => {

    withPluginApi('0.11.2', api => {

      api.registerConnectorClass('composer-fields', 'composer-topic-custom-field-container', {
        setupComponent(attrs, component) {
          const model = attrs.model;

          if (!isDefined(model[field.name]) && model.topic && model.topic[field.name]) {
            model.set(field.name, model.topic[field.name]);
          }

          let props = {
            fieldName: field.name,
            fieldValue: model.get(field.name)
          }
          component.setProperties(Object.assign(props, fieldInputTypes(field.type)));
        },

        actions: {
          onChangeField(fieldValue) {
            this.set(`model.${field.name}`, fieldValue);
          }
        }
      });

      api.registerConnectorClass('edit-topic', 'edit-topic-custom-field-container', {
        setupComponent(attrs, component) {
          const model = attrs.model;

          let props = {
            fieldName: field.name,
            fieldValue: model.get(field.name)
          }
          component.setProperties(Object.assign(props, fieldInputTypes(field.type)));
        },

        actions: {
          onChangeField(fieldValue) {
            this.set(`buffered.${field.name}`, fieldValue);
          }
        }
      });

      api.serializeOnCreate(field.name);
      api.serializeToDraft(field.name);
      api.serializeToTopic(field.name, `topic.${field.name}`);

      api.registerConnectorClass('topic-title', 'topic-title-custom-field-container', {
        setupComponent(attrs, component) {
          const model = attrs.model;
          const controller = container.lookup('controller:topic');

          component.setProperties({
            fieldName: field.name,
            fieldValue: model.get(field.name),
            showField: !controller.get('editingTopic') && isDefined(model.get(field.name))
          });

          controller.addObserver('editingTopic', () => {
            if (this._state === 'destroying') return;
            component.set('showField', !controller.get('editingTopic') && isDefined(model.get(field.name)));
          });

          model.addObserver(field.name, () => {
            if (this._state === 'destroying') return;
            component.set('fieldValue', model.get(field.name));
          });
        }
      });

      api.modifyClass('component:topic-list-item', {
        customFieldName: field.name,
        customFieldValue: alias(`topic.${field.name}`),

        @discourseComputed('customFieldValue')
        showCustomField: (value) => (isDefined(value))
      });

    });


    });
  }
}
1 Like
20

I haven’t tested it, but, I believe the reason you are seeing only 1/3 fields is its looping over and registering a non-unique connector class and overriding the previous one.

In general, for the client side, rather than looping through the custom fields and declaring the api methods. I suggest you define components for each field separately, or at least separate actions as you’ll probably need to have different logic associated with each field?

The only portion I would loop over and declare is this:

  api.serializeOnCreate(field.name);
      api.serializeToDraft(field.name);
      api.serializeToTopic(field.name, `topic.${field.name}`);

The rest of the components, its probably best to create separate logic for each case.

3 Likes
21

@keegan that worked! thank you so much for all the insights. Couldn’t have done it without your help.

4 Likes