python-graphql-server/main.py at main · smart-developer1791/python-graphql-server · GitHub

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# FastAPI server with pure GraphQL handling + custom GraphiQL UI
# -----------------------------------------------
from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse, HTMLResponse
from fastapi.middleware.cors import CORSMiddleware
from graphql import graphql_sync
from schema import schema  # Import the GraphQL schema defined in schema.py

# Initialize FastAPI application
app = FastAPI(title="Python GraphQL Server")

# --------------------------
# CORS (Cross-Origin Resource Sharing)
# Allow requests from any origin, with any method and headers.
# This mimics the permissive CORS setup from Ruby/Rust versions.
# --------------------------
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)

# --------------------------
# GraphQL endpoint (POST /graphql)
# Accepts JSON payload with 'query' and optional 'variables'
# --------------------------
@app.post("/graphql")
async def graphql_server(request: Request):
    # Parse request JSON body
    body = await request.json()
    query = body.get("query")  # GraphQL query string
    variables = body.get("variables")  # Optional variables dictionary

    # Execute query synchronously using graphql-core
    # Returns an ExecutionResult object
    result = graphql_sync(schema, query, variable_values=variables)

    # Convert ExecutionResult to JSON-friendly dict
    response = {}
    if result.data:
        response["data"] = result.data
    if result.errors:
        # Convert errors to string messages
        response["errors"] = [str(e) for e in result.errors]

    # Return JSON response
    return JSONResponse(response)


# --------------------------
# GraphiQL UI (GET /)
# Interactive in-browser IDE for exploring the GraphQL API
# --------------------------
GRAPHIQL_HTML = """
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <title>Python GraphQL Server</title>
    <link
      href="https://unpkg.com/graphiql@2.2.0/graphiql.min.css"
      rel="stylesheet"
    />
  </head>
  <body style="margin:0; height:100vh;">
    <!-- Container for GraphiQL -->
    <div id="graphiql" style="height:100vh"></div>

    <!-- React and ReactDOM are required for GraphiQL -->
    <script src="https://unpkg.com/react@18/umd/react.production.min.js"></script>
    <script src="https://unpkg.com/react-dom@18/umd/react-dom.production.min.js"></script>
    <script src="https://unpkg.com/graphiql@2.2.0/graphiql.min.js"></script>

    <script>
      // Function used by GraphiQL to send queries/mutations
      const graphQLFetcher = (graphQLParams) =>
        fetch("/graphql", {
          method: "post",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify(graphQLParams),
        }).then((response) => response.json());

      // Render GraphiQL interface
      ReactDOM.render(
        React.createElement(GraphiQL, { fetcher: graphQLFetcher }),
        document.getElementById("graphiql")
      );
    </script>
  </body>
</html>
"""

@app.get("/", response_class=HTMLResponse)
async def graphiql():
    """Serve the GraphiQL UI at root path."""
    return GRAPHIQL_HTML