It is difficult to express what GraphQL is in one word, but I personally recognize it as "a kind of protocol that expresses API". Often compared to the REST API. With REST API
curl http://example.com/users/123/posts/
In GraphQL, you can hit it like this
curl http://example.com/graphql -X POST --data '
{
user("123") {
posts {
title
}
}
}
'
Hit like. The REST API makes requests to various URLs such as / users / / users / 123 / / users / 123 / posts / to get the desired information, but GraphQL has one end. By throwing various queries to the points, you can get all the necessary information (except unnecessary information) with one request.
I wish I could use the GraphQL API in a hurry, so I only read the Queries and Mutations and Schemas and Types of the official GraphQL guide (https://graphql.org/learn/). I recommend it because you can get an overview just by reading two slightly longer pages.
However, there is one caveat. ** Don't ponder the meaning of the APIs that appear as examples. ** For example, the following query appears at the beginning.
{
hero {
name
}
}
In response, the sample API returns this response:
{
"data": {
"hero": {
"name": "R2-D2"
}
}
}
When I look at this example, I'm wondering, "Why do you return R2-D2 even though you didn't specify hero_id?" "If you don't specify hero_id, why should you return all heroes?" As a result, it hindered the overall understanding. In reality, this API is just a sample, so you should ignore its practicality and assume that it is something like that. There is simply a "Query called hero that takes one Episode as an optional argument and returns one Character".
Apollographql / starwars-server is a reproduction of the mysterious Star Wars API that appears in the official GraphQL guide above. After this, I will use it to hit from Ruby, so let's start it quickly. If you can access http: // localhost: 8080 / graphql from your browser, the startup is successful.
There is graphql / swapi-graphql with a similar name, but it is different because it is a GraphQL wrapper for the more authentic Star Wars API. be careful.
There is github / graphql-client as a GraphQL Client made by Ruby. I was very relieved that github is the owner, so I will use this for the time being.
It is also written in the README, but use it as follows.
require "graphql/client"
require "graphql/client/http"
module SWAPI
#http adapter set
HTTP = GraphQL::Client::HTTP.new("http://localhost:8080/graphql")
#Get GraphQL Schema information from the API server using the above
Schema = GraphQL::Client.load_schema(HTTP)
#Create a client using the above
Client = GraphQL::Client.new(schema: Schema, execute: HTTP)
end
HeroQuery = SWAPI::Client.parse <<~'GRAPHQL'
{
hero {
name
}
}
GRAPHQL
result = SWAPI::Client.query(HeroQuery)
pp result.to_h
In the above, Schema information is obtained from the server, but it seems that there is also a way to save it locally in advance and load it as follows.
module SWAPI
#Set http adapter (same as above)
HTTP = GraphQL::Client::HTTP.new("http://localhost:8080/graphql")
#Get GraphQL Schema information from a local file
Schema = GraphQL::Client.load_schema("path/to/schema.json")
#Create a client using the above (same as above)
Client = GraphQL::Client.new(schema: Schema, execute: HTTP)
end
#Get GraphQL Schema information from API server and output to local file
GraphQL::Client.dump_schema(SWAPI::HTTP, "path/to/schema.json")
# ...
If you want to give the query an Operation Name, you need to pass the argument of SWAPI :: Client.query () with the module name.
HeroQuery = SWAPI::Client.parse <<~'GRAPHQL'
#If you name it NameOfHero ...
query NameOfHero {
hero {
name
}
}
GRAPHQL
#HeroQuery instead of HeroQuery::You need to pass NameOfHero!
result = SWAPI::Client.query(HeroQuery::NameOfHero)
If you forget this, you will get the error ʻexpected definition to be a GraphQL :: Client :: OperationDefinition but was GraphQL :: Language :: Nodes :: Document (TypeError)`.
Also, because of this, you can't necessarily name names that start with a lowercase letter (you'll get the error client.rb: 241: in'const_set': wrong constant name ... (NameError)).
I feel that all the issues around this ↓ simply overlook this specification.
I was addicted to it because it wasn't specified in the README ... (Contribution chance?)
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