Snowflaqe

A dotnet CLI tool to work with GraphQL queries. It allows for static query verification and advanced type checking against a remote or local schema as well as generating type-safe clients for F# and Fable (more generation targets in the future).

Installation

Install as a global dotnet CLI tool

dotnet tool install snowflaqe -g

Using The Tool

Create a JSON file called snowflaqe.json with the following shape:

{
    "schema": "<schema>",
    "queries: "<queries>",
    "project": "<project>",
    "output": "<output>"
    ["errorType"]: <custom error type>,
    ["target"]: "<target>",
    ["overrideClientName"]: "<clientName>"
}

Where

• <schema> can be one of:
  • A URL to the GraphQL backend
  • A relative path to another JSON file containing the output of the standard Introspection query which you can execute against the backend yourself (this allows for offline verification and type-checking)
  • A relative path to a file with extension .gql or .graphql containing the schema definitions and types
• <queries> is an absolute or relative path to a directory that contains *.gql files that contain individual GraphQL queries that snowflaqe will run the verification against.
• <project> is the name of the project will be generated.
• <output> is an absolute or relative path to a directory where the project will be generated
• <errorType> optional custom error type to be generated. See below to learn more.
• <clientName> optional name for the GraphqlClient class which is {project}GraphqlClient by default when you don't provide this property.
• <target> optional the code-generation target which can either be fable (default), fsharp or shared.

Using shared as a code generation target actually builds 3 projects! One contains just the types and can be shared across platforms. The other two reference this shared projects and implmenent Fable specific client and dotnet specific client, respectively.

After creating the configuration file. You can cd your way to where you have the config file and run:

snowflaqe

which will by default only do static query verification and static type-checking against the <schema>. You can also reference the configuration file in another directory via a relative path:

snowflaqe --config ./src/snowflaqe.json

In this case, the file doesn't necessarily have to be called snowflaqe.json.

Generate Client Project

snowflaqe --generate

snowflaqe --config ./path/to/snowflaqe.json --generate

Will generate a full project in the designated output directory.

Custom Error Type

By default, the error type that is generated in the global types looks like this:

type ErrorType = { message: string }

This type is important because every request you make to the GraphQL backend returns Result<Query, ErrorType list> but the errors that come back are usually determined by the backend and not exposed through the schema. That is why you can customize this error type using the errorType configuration element:

{
    "schema": "<schema>",
    "queries: "<queries>",
    "project": "<project>",
    "output": "<output>",
    "errorType": {
        "CustomErrorType": {
            "Message": "string"
            "Path": "string list"
            "RequestId": "string"
        }
    }
}

which will generate:

type CustomErrorType = {
    Message: string
    Path: string list
    RequestId: string
}

Not Supported

There are a couple of features of the GraphQL specs which snowflaqe doesn't (yet) know how to work with:

• GraphQL Union Types
• Subscriptions (non-goal of the tool, maybe in the future)