make multiple selection query to appwrite with graphql from web sdk

I have a list of documents, with field_1, field_2, …

Using graphql from the web skd (on localhost), i want to perform two requests

1.get all documents as field_1 = “a” AND field_2 = “b”

2.get all documents as field_1 = “a” OR field_2 = “b”

Folowing the doc, i wrote this code:

`const {Client, Databases, Query, Graphql} =Appwrite;
const client = new Client()
.setEndpoint(“http://localhost:8080/v1/graphql”) // Your API Endpoint
.setProject(project_id) // Your project ID

const graphql = new Graphql(client);

const query = graphql.query({
query: query { databasesListDocuments( databaseId: "${db_id}", collectionId: "${collectionId}", queries: ["equal(\"field_1\", \"a\"), equal(\"field_2\", \"b\")"] ) { total documents { _id data } } }
})`

As result i have an array of error, with messages like:

message: “Field “databasesListDocuments” argument “queries” requires type String, found field_1.”

message: “Field “databasesListDocuments” argument “queries” requires type String, found a.”

…

What is the problem ?

How can i perform this request ?