Evolutility-Server-Node ·

Model-driven REST or GraphQL backend for CRUD and more, using Node.js, Express, and PostgreSQL.

Evolutility-Server-Node provides a set of generic REST or GraphQL endpoints for CRUD (Create, Read, Update, Delete) and simple charts.

For a matching model-driven Web UI, use Evolutility-UI-React or Evolutility-UI-jQuery.

Table of Contents

1. Installation
2. Setup
3. Configuration
4. Models: Object - Field - Collection - Sample model
5. REST API: Get - Update - Charts - More
6. GraphQL: Object by Id - List - Charts data
7. License

Installation

Download or clone from GitHub.

# To get the latest stable version, use git from the command line.
git clone https://github.com/evoluteur/evolutility-server-node

or use the npm package:

# To get the latest stable version, use npm from the command line.
npm install evolutility-server-node

Dependencies: Node.js, Express, PostgreSQL, and PG-Promise.

Evolutility-Server-Node works with Node.js v12.12.0 (not yet compatible w/ later versions).

Setup

After installing Evolutility-Server-Node, follow these steps:

1. Create a PostgreSQL database.

2. In the file config.js set the PostgreSQL connection string and the schema name to access your new database.

3. Maybe, also change other config options in the same file.

4. In the command line type the following:

# Install dependencies
npm install

# Create sample database w/ demo tables
npm run makedb

# Run the node.js server
npm start

Note: The database creation and population scripts are logged in the files "evol-db-schema-{datetime}.sql" and "evol-db-data-{datetime}.sql".

URLs on localhost:

• REST: http://localhost:2000/api/v1/
• GraphQL: http://localhost:2000/graphql

Configuration

Configuration options are set in the file config.js.

Models

To be accessible by the REST API, each database table must be described in a model. Models contain the name of the driving table and the list of fields/columns present in the API.

• Object
• Field
• Collection
• Sample model

Object

Field

Collection

Multiple Master-Details can be specified with collections.

Example of collection in Wine cellar.

Sample model

Below is the model for a To-Do app.

module.exports = {
    id: "todo",
    table: "task",
    titleField: "title",
    searchFields: ["title", "duedate", "description"],
    fields: [
        {
            id: "title", 
            column: "title", 
            type: "text", 
            required: true, 
            inMany: true
        },
        {
            id: "duedate", 
            column: "duedate", 
            type: "date", 
            inMany: true
        },
        {
            id: "category", 
            column: "category_id", 
            type: "lov", 
            lovTable: "task_category",
            inMany: true
        },
        {
            id: "priority", 
            column: "priority_id", 
            type: "lov", 
            lovTable: "task_priority", 
            required: true, 
            inMany: true
        {
            id: "complete", 
            column: "complete", 
            type: "boolean", 
            inMany: true
        },
        {
            id: "description", 
            column: "description", 
            type: "textmultiline"
        }
    ]
};

More sample models: Address book, Restaurants list, Wine cellar, Graphic novels inventory.

REST API

Evolutility-Server-Node provides a generic RESTful API for CRUD (Create, Read, Update, Delete) and more. It is inspired from PostgREST.

• Get
• Update
• Charts
• More

When running Evolutility-Server-Node locally, the base url is http://localhost:2000/api/v1/.

Requesting Information

Get One

Gets a specific record by ID.

GET /{model.id}/{id}

GET /todo/12

By default this endpoint returns nested collections with the record. For optimization, collections can be ommited by using the parameter "shallow".

GET /{model.id}/{id}?shallow=1

GET /todo/12?shallow=1

Get Many

Gets a list of records.

GET /{model.id}

GET /todo

Filtering

You can filter result rows by adding conditions on fields, each condition is a query string parameter.

GET /{model.id}/{field.id}={operator}.{value}

GET /todo?title=sw.a
GET /todo?priority=in.1,2,3

Adding multiple parameters conjoins the conditions:

todo?complete=0&duedate=lt.2018-12-24

For each field a sub-set of the operators below will be supported by the API (depending field types).

Searching

You can search for a specific string across multiple fields at once with the "search" parameter. The list of fields to be searched is specified with "searchFields" in the model (if unspecified, text fields flagged with "inMany" for list view will be used).

GET /{model.id}?search={value}

GET /todo?search=translation

Ordering

The reserved word "order" reorders the response rows. It uses a comma-separated list of fields and directions:

GET /{model.id}?order={field.id}.{asc/desc}

GET /todo?order=priority.desc,title.asc

If no direction is specified it defaults to ascending order:

GET /todo?order=duedate

Limiting and Pagination

The reserved words "page" and "pageSize" limits the response rows.

GET /{model.id}?page={pageindex}&pageSize={pagesize}

GET /todo?page=0&pageSize=50

Formatting

By default all APIs return data in JSON format. This API call allows to request data in CSV format (export to Excel). This feature is using csv-express.

GET /{model.id}?format=csv

GET /todo?format=csv

Notes: In the returned data every object has an extra property "_full_count" which indicate the total number of records in the query (before limit).

Updating Data

Record creation

To create a row in a database table post a JSON object whose keys are the names of the columns you would like to create. Missing keys will be set to default values when applicable.

POST {model.id} {data}

POST /todo
{ title: 'Finish testing', priority: 2}

Even though it is a "POST", the request also returns the newly created record. It is not standard but it saves the UI a subsequent call.

Update

PATCH or PUT can be used to update specific records.

PATCH /{model.id}/{id} {data}

PATCH /todo/5
{ title: 'Finish testing', priority: 2}

PUT /{model.id}/{id} {data}

PUT /todo/5
{ title: 'Finish testing', priority: 2}

Notes: The request returns the updated record. It is not standard but it saves the UI a subsequent call.

Deletion

Simply use the DELETE verb with the id of the record to remove.

DELETE /{model.id}/{id}

DELETE /todo/5

To delete multiple records at once, pass multiple ids (separated by commas).

DELETE /{model.id}/{id1},{id2},{id3}

DELETE /todo/5,7,12

Extras endpoints

In addition to CRUD, Evolutility-Server-Node provides a few endpoints for Charts, Lists of values, file upload, and API discovery.

Discovery

Returns the list of all active objects with urls to their REST end-points.

GET /

It is also possible to get a more detailed list of REST end-points for a specific model.

GET /?id={model.id}

GET /?id=todo
GET /?id=contact

Note: These end-point must be enabled in the configuration with { apiInfo: true }.

Charts

For charts data, it is possible to get aggregated data for field of types lov, boolean, integer, decimal, and money. Use the attribute "noCharts" to exclude a field from Charts.

GET /{model.id}/chart/{field id}

GET /todo/chart/category

Stats

Returns the total count, and the min, max, average, and total for numeric fields in the model.

GET /{model.id}/stats

GET /todo/stats

Lists of Values

Dropdown fields in the UI (field.type="lov" in the model) have a REST endpoint to get the list of values. This endpoint can also take a search query parameter.

GET /{model.id}/lov/{field.id}

GET /todo/lov/category
GET /todo/lov/category?search=pro

File upload

This endpoint lets you upload a file. The current (naive) implementation simply saves the file on the file server in a folder named like the model id (inside the folder specified by the option "uploadPath" in config.js).

POST /{model.id}/upload/{id}

POST /comics/upload/5

With query parameters: file and "field.id".

Nested collections

If the model has collections defined, they can be queried with this end-point.

GET /{model.id}/collec/{collection.id}?id={id}

GET /winecellar/collec/wine_tasting?id=1

Models

When storing models in evol_object and evol_field tables, they can be queried through REST.

Get all models flagged as active.

GET /meta/models

Get a model by ID (integer).

GET /meta/model/{modelid}

GET /meta/model/1

Note: Schema and Models end-points must be enabled in the configuration with { apiDesigner: true }.

Schema tables and columns

These endpoints query for the database structure (rather than the data), and returns lists of tables and columns.

List of schema tables (props: table, type, readOnly).

GET /db/tables

List of columns (props: column, type, required) for a specified table.

GET /db/{table_name}/columns

GET /db/contact/columns
GET /db/task/columns

Note: These end-point must be enabled in the configuration with { schemaQueries: true }.

API version

This endpoint gets the API version (as specified in the project's package.json file).

GET /version

GraphQL

Evolutility-Server-Node provides a GraphQL interface using the same models as the REST API.

• Object by Id
• List
• Charts data

By default GraphiQL runs at http://localhost:2000/graphql. It can be enabled or disabled in config.js.

Object by Id

For getting a single record by Id.

{ 
    contact (id: 1 ){
        firstname
        lastname
        category_txt
        email
  }
}

View in GraphiQL

List of objects

All objects are exposed for queries with search and filters. Filter use the same syntax for conditions as the REST API (for example: { firstname: "sw.A" } for "Firstname starts with "A").

Fields of type "lov" (List of values) are represented as 2 fields for Id and value.

{ 
    # List - priority tasks not completed
    todos ( complete: "false", priority: "lt.3" ){
	    title
	    description
	    priority
	    priority_txt
	    category
	    category_txt
	    complete
  }
    # List - contacts w/ firstname starts w/ "A" and search for "ab"
  	contacts (search: "ab", firstname: "sw.A") { 
	    id
	    firstname
	    lastname
	    category_txt
	    email
  }
}

View in GraphiQL.

Charts data

For all objects records can be aggregated and counted by field (for fields of numeric or "lov" types).

{ 
  # Charts - contacts by categories
  contacts_by_category: contact_charts(fieldId:"category"){
    label 
    value
  }
  # Charts - tasks by priorities
  task_by_priority: todo_charts(fieldId:"priority") {
    label 
    value
  }
  # Charts - restaurants by cuisine
  restaurants_by_cuisine: restaurant_charts(fieldId:"cuisine") {
    label 
    value
  }
}

View in GraphiQL

License

Copyright (c) 2021 Olivier Giulieri.

Evolutility-Server-Node is released under the MIT license.