eloquent code

The GraphQL Schema Language provides a very handy feature to indicate that a field has been deprecated. This will show as a prominent text box on auto-complete in the query builder in GraphiQL, as well as in the documentation explorer. This is a great way to indicate to developers using your GraphQL API that code using a field should  ideally be changed. The reason for deprecation can be included as an annotation right in the schema itself!

In the following schema, we have indicated that the field topic is deprecated for the Book type:

type Book {
   id: Int!,
   title: String,
   topic: String @deprecated (reason: "Field is no longer needed")
}

When we explore the schema with GraphiQL, the deprecation message will display when viewing the field.

There are many ways to install Node, but for the latest version you cannot use apt install or apt-get install.

The best way is to use the Node Version Manager (nvm) to install Node.

Note that there is no Ubuntu package for nvm and nvm is not a regular binary, but rather a shell function.

Note also that nvm is not meant to be used with sudo ! The install will be for your current regular user.

Before installing: make sure to have a .bash_profile file in your home directory.

The following steps will install nvm and node (and hence npm).

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.8/install.sh | bash

Reload your terminal.

Find the latest version listed by the following command:

nvm ls-remote

At the time of writing the latest was 9.5.0, so:

nvm install 9.5.0

nvm use 9.5.0

Check that the latest versions of node and npm are ready:

node -v

npm -v

PostGraphQL will provide GraphQL access automatically to your data stored in a PostgreSQL database.

Assuming we have PostgreSQL installed already with at least one database created but we don’t have Node yet – install Node Version Manager (nvm), the latest version of Node.js and PostGraphQL:

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.8/install.sh | bash

nvm install node 

npm install -g postgraphql

Assuming we have a database called my_database and a user my_database_usr, in one terminal run the PostGraphQL server:

postgraphql -c "postgres://my_database_usr:password@localhost:5432/my_database"

The server should be running on port 5000 on localhost.

Note: make sure you have a PostgreSQL version newer than 9.4 or else you will see this error:

error: function pg_catalog.pg_relation_is_updatable(oid, boolean) does not exist

In another terminal, send an HTTP POST request to see what data is available:

curl -X POST "http://localhost:5000/graphql" -H "Content-type: application/json" -d "{\"query\": \"{__schema{types{name}}}\"}"

The following example query assumes a table “books” with a field “title” in my_database. The cURL command is below:

curl -X POST "http://localhost:5000/graphql" -H "Content-type: application/json" -d "{\"query\": \"{allBooks{edges{node{title}}}}\"}"

In a browser you can also explore the data with GraphiQL at:

http://localhost:5000/graphiql

 

A list of useful vim (vi) editing commands.

 

cc

Replace entire line: delete and enter input mode.

:r filename

Paste contents of filename into current file.

:x

Write file and exit. Short for :wq