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Hodur is a domain modeling approach and collection of libraries to Clojure. By using Hodur you can define your domain model as data, parse and validate it, and then either consume your model via an API or use one of the many plugins to help you achieve mechanical results faster and in a purely functional manner.

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Hodur Contentful Schema

CircleCI Clojars Clojars License Status


Hodur is a descriptive domain modeling approach and related collection of libraries for Clojure.

By using Hodur you can define your domain model as data, parse and validate it, and then either consume your model via an API making your apps respond to the defined model or use one of the many plugins to help you achieve mechanical, repetitive results faster and in a purely functional manner.

This Hodur plugin provides the ability to generate Contentful schemas out of your Hodur model. You can then apply your schema to your Contentful environments.


For a deeper insight into the motivations behind Hodur, check the motivation doc.

Getting Started

Hodur has a highly modular architecture. Hodur Engine is always required as it provides the meta-database functions and APIs consumed by plugins.

Therefore, refer the Hodur Engine's Getting Started first and then return here for Datomic-specific setup.

After having set up hodur-engine as described above, we also need to add hodur/contentful-schema, the plugin that creates Contentful Schemas out of your model to the deps.edn file:

  {:deps {hodur/engine            {:mvn/version "0.1.6"}
          hodur/contentful-schema {:mvn/version "0.1.1"}}}

You should require it any way you see fit:

  (require '[hodur-engine.core :as hodur])
  (require '[hodur-contentful-schema.core :as hodur-contentful])

Let's expand our Person model from the original getting started by "tagging" the Person entity for Contentful. You can read more about the concept of tagging for plugins in the sessions below but, in short, this is the way we, model designers, use to specify which entities we want to be exposed to which plugins.

  (def meta-db (hodur/init-schema
                '[^{:contentful/tag-recursive true}
                  [^String first-name
                   ^String last-name]]))

The hodur-contentful-schema plugin exposes a function called schema that generates your model as a Contentful schema payload:

  (def contentful-schema (hodur-contentful/schema meta-db {:space-id "<YOUR_SPACE_ID>"))

You should replace <YOUR_SPACE_ID> with the space id of your Contentful instance.

When you inspect contentful-schema, this is what you have:

    "contentTypes" : [ {
      "sys" : {
        "space" : {
          "sys" : {
            "type" : "Link",
            "linkType" : "Space",
            "id" : "<YOUR_SPACE_ID>"
        "id" : "person",
        "type" : "ContentType",
        "publishedVersion" : 1
      "name" : "Person",
      "description" : null,
      "fields" : [ {
        "id" : "firstName",
        "name" : "First Name",
        "type" : "Symbol",
        "localized" : false,
        "required" : true,
        "validations" : [ ],
        "omitted" : false,
        "disabled" : false
      }, {
        "id" : "lastName",
        "name" : "Last Name",
        "type" : "Symbol",
        "localized" : false,
        "required" : true,
        "validations" : [ ],
        "omitted" : false,
        "disabled" : false
      } ]
    } ],
    "editorInterfaces" : [ {
      "sys" : {
        "id" : "default",
        "type" : "EditorInterface",
        "space" : {
          "sys" : {
            "type" : "Link",
            "linkType" : "Space",
            "id" : "<YOUR_SPACE_ID>"
        "contentType" : {
          "sys" : {
            "id" : "person",
            "type" : "Link",
            "linkType" : "ContentType"
      "controls" : [ {
        "fieldId" : "firstName",
        "widgetId" : "singleLine"
      }, {
        "fieldId" : "lastName",
        "widgetId" : "singleLine"
      } ]
    } ]

In order to import the model above to your Contentful space, first make sure you have NodeJS installed, then save the JSON returned from schema to a file (i.e. my-model.json).

You will also need your Contentful settings to either on a contentful-config.json file to run the Contentful CLI. More info on the config file here. For the purposes of this getting started, I'm using something along the lines of:

  "spaceId": "<YOUR_SPACE_ID>",
  "managementToken": "<YOUR_MANAGEMENT_TOKEN>"

Then you can run the importer with the following command:

$ npx contentful-cli space import --config contentful-config.json --content-file my-model.json

You can also specify the environment you are importing the model to with the parameter --environment-id.

Model Definition

All Hodur plugins follow the Model Definition as described on Hodur Engine's documentation.

Setting Display Name

The display name of entities and fields can be controlled by using the marker :contentful/display-name:

  [^{:contentful/display-name "My Dream List"}
   [^{:contentful/display-name "The Dream Title"}

If no :contentful/display-name is provided, the plugin will default to a capitalized version of the entity or field name.

Making a Field the Display of an Entity

Contentful uses one of the fields of each entity as a visual identifier for editors on its admin interface.

In order to specify which field is used for it, mark it with :contentful/display-field true.

Documenting Entities and Fields

The marker :doc is fully supported. Both entity and field documentations will show on the admin for editors.

Specifying Contentful Types

Contentful-specific types can be specified by using the marker :contentful/type.

The supported basic types are:

  • Symbol (short text - default for String)
  • Text (long text)
  • Integer (default for Integer)
  • Number (default for Float)
  • Date (default for DateTime)
  • Boolean (default for Boolean)
  • Object
  • Location
  • RichText

In general you don't need to specify the following ones because they are managed internally by the plugin but, for reference:

  • Array (default for any multiple cardinality)
  • Link (default for linking to one asset and other user-specified entities)

Last but not least, you can also specify Asset as a special type that will point to an asset (or more if cardinality is many) on the digital asset manager:

  • Asset

Asset Fields

By specifying :contentful/type "Asset" you are letting Contentful know that a certain field should be associated with and asset from the digital asset manager.

This field can also have cardinality of many ([0 n]) and it should let editors choose several assets for it.

Please refer to the section describing further validations down below for examples on how to limit to certain kind of assets (images for instance) and certain image features.

Also, refer to the widget configuration below as there are different widgets that can be used for asset selection.

ID Fields

ID fields are sent to Contentful as Symbol by default. Please do provide a different :contentful/type if you need something else.

In addition, ID fields are automatically marked as unique by default. If you prefer to control this more granularly, use a more basic data type (String i.e.) and detail your validations manually as documented in the section below.

Enum Fields

Fields that point to :enum entities will be sent to Contentful as Symbol by default. If you need a different type, please provide it via :contentful/type.

By default the values of the enum are used as an :in validation for the field. Therefore, the editor will be constrained to select one of the options.

A dropdown widget is chosen by default in order to help editors understand the selection. If you prefer a different rendering (such as a radio or a singleLine) you can specify it with the :contentful/widget-id marker as documented in the respective section below.

Field Validations

This plugin acts as a pass-through to the validations specified on marker :contentful/validations. This marker, when specified, must be an array of at least one entry. The full documentation of all the field validations available on Contentful can be found here.

Here's an example showing some of these combined. They are pretty self-explanatory:

   [;; will validate that `platform-field` is either `iOS` or `Android`
    ^{:type String
      :contentful/validations [{:in ["iOS" "Android"]}]}

    ;; will validate that `range-field` is between 5 and 15 with a custom message
    ^{:type Integer
      :contentful/validations [{:range {:min 5
                                        :max 15}
                                :message "Must be between 5 and 15"}]}

    ;; will validate that `regexp-field` follows regexp `/^such/im`
    ^{:type String
      :contentful/validations [{:regexp {:pattern "^such"
                                         :flags "im"}}]}

    ;; will validate that `unique-field` is unique
    ^{:type String
      :contentful/validations [{:unique true}]}

    ;; will validate that `date-range-field` is between the min and max date
    ^{:type DateTime
      :contentful/validations [{:date-range {:min "2017-05-01"
                                             :max "2020-05-01"}}]}

    ;; will validate that `enabled-node-types-field` has only the specified node types active
    ^{:type String
      :contentful/type "RichText"
      :contentful/validations [{:enabled-node-types ["heading-1"

    ;; will validate that `enabled-marks-field` has only the specified marks enabled
    ^{:type String
      :contentful/type "RichText"
      :contentful/validations [{:enabled-marks ["bold" "italics"]}]}

    ;; will validate that `multiple-validations-field` is both foo or bar, and between
    ;; 2 and 5 characters with custom messages
    ^{:type String
      :contentful/validations [{:in ["foo" "bar"]
                                :message "Should be foo or bar"}
                               {:size {:min 2
                                       :max 5}
                                :message "Should have 2 to 5 characters"}]}

    ;; will validate that `multiple-asset-validations-field` is an image, within certain
    ;; dimensions foo or bar, and certain byte size between with custom messages
    ^{:contentful/type "Asset"
      :contentful/validations [{:link-mimetype-group ["image"]
                                :message "Must be of MIME-Type image"}
                                {:width {:min 100
                                         :max 1000}
                                 :height {:min 200
                                          :max 2300}}
                                :message "Width must be 100-1000 and height 200-2300"}
                               {:asset-file-size {:min 1048576
                                                  :max 8388608}
                                :message "File must be between 1048576B and 8388608B"}]}

Choosing Widget for Fields

In order to make the experience more interesting for editors, Contentful supports several dedicated widgets. A widget for a field can be specified with the marker :contentful/widget-id. If a widget is not specified a reasonable default one will be selected.

A full list of the available widgets can be found here. As of this writing, the options are:

Widget ID Applicable field types Description
assetLinkEditor Asset Search, attach, and preview an asset.
assetLinksEditor Asset (array) Search, attach, reorder, and preview multiple assets.
assetGalleryEditor Asset (array) Search, attach, reorder, and preview multiple assets in a gallery layout
boolean Boolean Radio buttons with customizable labels.
datePicker Date Select date, time, and timezone.
entryLinkEditor Entry Search and attach another entry.
entryLinksEditor Entry (array) Search and attach multiple entries.
entryCardEditor Entry Search, attach, and preview another entry.
entryCardsEditor Entry (array) Search, attach and preview multiple entries.
numberEditor Integer, Number A simple input for numbers.
rating Integer, Number Uses stars to select a number.
locationEditor Location A map to select or find coordinates from an address.
objectEditor Object A code editor for JSON
urlEditor Symbol A text input that also shows a preview of the given URL.
slugEditor Symbol Automatically generates a slug and validates its uniqueness across entries.
listInput Symbol (array) Text input that splits values on , and stores them as an array.
checkbox Symbol (array) A group of checkboxes. One for each value from the in validation on the content type field
tagEditor Symbol (array) A text input to add a string to the list. Shows the items as tags and allows to remove them.
multipleLine Text A simple <textarea> input
markdown Text A full-fledged markdown editor
singleLine Text, Symbol A simple text input field
dropdown Text, Symbol, Integer, Number A element. It uses the values from an in validation on the content type field as options.
radio Text, Symbol, Integer, Number A group of radio buttons. One for each value from the in validation on the content type field

Here's a simple example:

   [^{:type String
      :contentful/widget-id "urlEditor"} url
    ^{:type Integer
      :contentful/widget-id "rating"}    stars]]

Widget Settings

With the exception of the help text, all other widget settings are available via Hodur with specific markers.

For boolean widget:

  • :contentful/true-label : Shows this text next to the radio button that sets this value to true. Defaults to "Yes".
  • :contentful/false-label : Shows this text next to the radio button that sets this value to false. Defaults to "No".

For rating widget:

  • :contentful/stars : Number of stars to select from. Defaults to 5.

For datePicker widget:

  • :contentful/format : One of "dateonly", "time", "timeZ" (default). Specifies whether to show the clock and/or timezone inputs.
  • :contentful/ampm : Specifies which type of clock to use. Must be one of the strings "12" or "24" (default).


   [^{:type Integer
      :contentful/widget-id "rating"
      :contentful/stars 10}

    ^{:type Boolean
      :contentful/true-label "Si!"
      :contentful/false-label "No!"}

    ^{:type DateTime
      :contentful/format "dateonly"}

    ^{:type DateTime
      :contentful/format "time"}

    ^{:type DateTime
      :contentful/format "timeZ"}

    ^{:type DateTime
      :contentful/ampm "12"}

Limitations & Assumptions

  • This plugin ignores interfaces and field parameters.
  • PascalCasing is used on naming entities and camelCasing is used on all fields
  • There are no validations on the widgets, validations, or other Contentful-specific markers. They are simply passed over to Contentful.
  • Unions are supported by creating entry relationships that support multiple content types.


If you find a bug, submit a GitHub issue.


This project is looking for team members who can help this project succeed! If you are interested in becoming a team member please open an issue.


Copyright © 2019 Tiago Luchini

Distributed under the MIT License (see LICENSE).


Hodur is a domain modeling approach and collection of libraries to Clojure. By using Hodur you can define your domain model as data, parse and validate it, and then either consume your model via an API or use one of the many plugins to help you achieve mechanical results faster and in a purely functional manner.





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