Regular expression to get variables in Graphql query

Question

I have a graphql query that I'd like to get the variable names and types. I'm using Apollo Client to handle my queries but I believe doesn't provide something to get variables names. Is there any API or library given that information?

Query example:

query Integrations($count: Int, $isAdmin: Boolean, $services: String) {
  repository(uri: "$count: Int, $isAdmin: Boolean, $services: String") {
    integrations(
      filter: { limit: $count, ignoreCase: $isAdmin, id: $services }
    ) {
      id
    }
  }
}

I'd like to receive an object like:

{
  "count": "Int",
  "isAdmin": "Boolean",
  "services": "String"
}

Please note that this case could be handle by a regular expression, like this one:

[^"$\s]*\$([a-zA-Z0-9]*):\s*(String|Int|Float|Boolean)[^"$\s]*

Unfortunately, also match the variables inside a string (line 2)

Any idea?

Answer 1

Is there any API or library given that information?

Yes. Apollo Client uses graphql-tag which generates an AST of the query using the official graphql-js parser.

You should find the variable names and types using this same API:

import { parse, print, getOperationAST } from 'graphql';

const document = parse('…');
// const query = document.definitions.find(def => def.operation == "query" && def.name.value == 'Integrations');
const query = getOperationAST(document, 'Integrations');
for (const varDef of query.variableDefinitions) {
    console.log(`Variable '${varDef.name.value}' has type ${print(varDef.type)}.`);
}

Don't use an ad-hoc regular expression.