I have two http endpoints setup:
GET /users/{userId}
GET /users/{userId}/notes/{noteId}
The GET User returns a payload which includes a list of multiple noteIds, which can be used to make multiple requests to the GET Note endpoint.
I am trying to configure Appsync to be able to fetch all of this data in a single query, but I can't get the list to populate with objects.
Schema:
type Query {
getUser(userId: String!): User
getNote(userId: String!, noteId: String!): Note
}
type User {
userId: ID!
firstName: String!
lastName: String!
notes: [Note]
}
type Note {
noteId: ID!
noteText: String!
createdDatetime: Int!
}
I have a data source setup for each of the endpoints and I have a resolver for getUser and for getNote - I also have a resolver for User.notes which is the same as getNote. These resolvers have this response mapping:
#if($ctx.error)
$util.error($ctx.error.message, $ctx.error.type)
#end
#if($ctx.result.statusCode == 200)
$ctx.result.body
#else
$utils.appendError($ctx.result.body, "$ctx.result.statusCode")
#end
My resolver for the GET Note (including User.note field resolver) endpoint looks like this:
{
"version": "2018-05-29",
"method": "GET",
"resourcePath": $util.toJson("/prod/users/$ctx.args.userId/notes/$ctx.args.noteId"),
"params":{
"headers":{
"Content-Type": "application/json",
}
}
}
I can see from the logs, that Appsync attempts to run the GET Note resolver, but that the resource path doesn't seem to get populated with any ids? (I can see this in the custom Authorizer on the endpoint, which logs out the method ARN which still includes the $ctx.args...
It feels like this is a common use case, but I can't find a solution, or examples anywhere. Is my approach correct, or do I need a different solution?
I think the first problem is with your User.notes resolver and how you are accessing userId and noteId. When you have field resolvers, you should use ctx.source to access the the parent field [Ref.]. For example, you should use ctx.source.userId in your User.notes field resolver.
Secondly, as you are going to fetch individual notes from your getNote HTTP endpoint, AppSync supports this type of behavior when proxied through AWS Lambda using BatchInvoke. Please see "Advanced Use Case: Batching" on this link to get better idea. Also, I think this SO post is relevant to your use case.
One other possibility is to have another HTTP endpoint to get all the user's notes at once but I am not sure if this is possible in your case.
How do I define and validate URL Query String Parameters for an AWS::Serverless::Api in a SAM template?
They don't seem to be mentioned in the documentation https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-resource-api.html
Just to be clear this is what I am talking about
The URL Query String Parameters is defined in AWS::Serverless::Function rather than AWS::Serverless::Api using RequestParameters property.
All parameter names must start with method.request and must be limited to method.request.header, method.request.querystring, or method.request.path.
For example to define email, name in URL Query String Parameters and Authorization in HTTP Request Headers u can do the following:
Events:
ApiEvent:
Type: Api
Properties:
Path: /path
Method: get
RequestParameters:
- method.request.querystring.email:
Required: true
Caching: false
- method.request.querystring.name:
Required: true
Caching: false
- method.request.header.Authorization:
Required: true
Caching: true
I hope this helps.
I think that your response is in another resource, AWS::ApiGateway::Method.
Check the documentation (search for Request Parameters):
The request parameters that API Gateway accepts. Specify request parameters as key-value pairs (string-to-Boolean mapping), with a source as the key and a Boolean as the value. The Boolean specifies whether a parameter is required. A source must match the format method.request.location.name, where the location is querystring, path, or header, and name is a valid, unique parameter name.
https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-apigateway-method.html#cfn-apigateway-method-requestparameters
for instance if we want to use
GET /user?name=bob
or
GET /user/bob
How would you pass both of these examples as a parameter to the Lambda function?
I saw something about setting a "mapped from" in the documentation, but I can't find that setting in the API Gateway console.
method.request.path.parameter-name for a path parameter named parameter-name as defined in the Method Request page.
method.request.querystring.parameter-name for a query string parameter named parameter-name as defined in the Method Request page.
I don't see either of these options even though I defined a query string.
As of September 2017, you no longer have to configure mappings to access the request body.
All you need to do is check, "Use Lambda Proxy integration", under Integration Request, under the resource.
You'll then be able to access query parameters, path parameters and headers like so
event['pathParameters']['param1']
event["queryStringParameters"]['queryparam1']
event['requestContext']['identity']['userAgent']
event['requestContext']['identity']['sourceIP']
The steps to get this working are:
Within the API Gateway Console...
Go to Resources -> Integration Request
Click on the plus or edit icon next to the templates dropdown (odd I know since the template field is already open and the button here looks greyed out)
Explicitly type application/json in the content-type field even though it shows a default (if you don't do this it will not save and will not give you an error message)
put this in the input mapping { "name": "$input.params('name')" }
click on the check box next to the templates dropdown (I'm assuming this is what finally saves it)
I have used this mapping template to provide Body, Headers, Method, Path, and URL Query String Parameters to the Lambda event. I wrote a blog post explaining the template in more detail: http://kennbrodhagen.net/2015/12/06/how-to-create-a-request-object-for-your-lambda-event-from-api-gateway/
Here is the Mapping Template you can use:
{
"method": "$context.httpMethod",
"body" : $input.json('$'),
"headers": {
#foreach($param in $input.params().header.keySet())
"$param": "$util.escapeJavaScript($input.params().header.get($param))" #if($foreach.hasNext),#end
#end
},
"queryParams": {
#foreach($param in $input.params().querystring.keySet())
"$param": "$util.escapeJavaScript($input.params().querystring.get($param))" #if($foreach.hasNext),#end
#end
},
"pathParams": {
#foreach($param in $input.params().path.keySet())
"$param": "$util.escapeJavaScript($input.params().path.get($param))" #if($foreach.hasNext),#end
#end
}
}
These days a drop-down template is included in the API Gateway Console on AWS.
For your API, click on the resource name... then GET
Expand "Body Mapping Templates"
Type in
application/json
for Content-Type (must be explicitly typed out) and click the tick
A new window will open with the words "Generate template" and a dropdown (see image).
Select
Method Request passthrough
Then click save
To access any variables, just use the following syntax (this is Python)
e.g. URL:
https://yourURL.execute-api.us-west-2.amazonaws.com/prod/confirmReg?token=12345&uid=5
You can get variables as follows:
from __future__ import print_function
import boto3
import json
print('Loading function')
def lambda_handler(event, context):
print(event['params']['querystring']['token'])
print(event['params']['querystring']['uid'])
So there is no need to explicitly name or map each variable you desire.
In order to pass parameters to your lambda function you need to create a mapping between the API Gateway request and your lambda function. The mapping is done in the Integration Request -> Mapping templates section of the selected API Gateway resource.
Create a mapping of type application/json, then on the right you will edit (click the pencil) the template.
A mapping template is actually a Velocity template where you can use ifs, loops and of course print variables on it. The template has these variables injected where you can access querystring parameters, request headers, etc. individually. With the following code you can re-create the whole querystring:
{
"querystring" : "#foreach($key in $input.params().querystring.keySet())#if($foreach.index > 0)&#end$util.urlEncode($key)=$util.urlEncode($input.params().querystring.get($key))#end",
"body" : $input.json('$')
}
Note: click on the check symbol to save the template. You can test your changes with the "test" button in your resource. But in order to test querystring parameters in the AWS console you will need to define the parameter names in the Method Request section of your resource.
Note: check the Velocity User Guide for more information about the Velocity templating language.
Then in your lambda template you can do the following to get the querystring parsed:
var query = require('querystring').parse(event.querystring)
// access parameters with query['foo'] or query.foo
The accepted answer worked fine for me, but expanding on gimenete's answer, I wanted a generic template I could use to pass through all query/path/header params (just as strings for now), and I came up the following template. I'm posting it here in case someone finds it useful:
#set($keys = [])
#foreach($key in $input.params().querystring.keySet())
#set($success = $keys.add($key))
#end
#foreach($key in $input.params().headers.keySet())
#if(!$keys.contains($key))
#set($success = $keys.add($key))
#end
#end
#foreach($key in $input.params().path.keySet())
#if(!$keys.contains($key))
#set($success = $keys.add($key))
#end
#end
{
#foreach($key in $keys)
"$key": "$util.escapeJavaScript($input.params($key))"#if($foreach.hasNext),#end
#end
}
As part of trying to answer one of my own questions here, I came across this trick.
In the API Gateway mapping template, use the following to give you the complete query string as sent by the HTTP client:
{
"querystring": "$input.params().querystring"
}
The advantage is that you don't have to limit yourself to a set of predefined mapped keys in your query string. Now you can accept any key-value pairs in the query string, if this is how you want to handle.
Note: According to this, only $input.params(x) is listed as a variable made available for the VTL template. It is possible that the internals might change and querystring may no longer be available.
Now you should be able to use the new proxy integration type for Lambda to automatically get the full request in standard shape, rather than configure mappings.
see: http://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-set-up-simple-proxy.html#api-gateway-set-up-lambda-proxy-integration-on-proxy-resource
GET /user?name=bob
{
"name": "$input.params().querystring.get('name')"
}
GET /user/bob
{
"name": "$input.params('name')"
}
The query string is straight forward to parse in javascript in the lambda
for GET /user?name=bob
var name = event.queryStringParameters.name;
This doesn't solve the GET user/bob question though.
A lot of the answers here are great. But I wanted something a little simpler.
I wanted something that will work with the "Hello World" sample for free. This means I wanted a simple produces a request body that matches the query string:
{
#foreach($param in $input.params().querystring.keySet())
"$param": "$util.escapeJavaScript($input.params().querystring.get($param))" #if($foreach.hasNext),#end
#end
}
I think the top answer produces something more useful when building something real, but for getting a quick hello world running using the template from AWS this works great.
The following parameter-mapping example passes all parameters, including path, querystring and header, through to the integration endpoint via a JSON payload
#set($allParams = $input.params())
{
"params" : {
#foreach($type in $allParams.keySet())
#set($params = $allParams.get($type))
"$type" : {
#foreach($paramName in $params.keySet())
"$paramName" : "$util.escapeJavaScript($params.get($paramName))"
#if($foreach.hasNext),#end
#end
}
#if($foreach.hasNext),#end
#end
}
}
In effect, this mapping template outputs all the request parameters in the payload as outlined as follows:
{
"parameters" : {
"path" : {
"path_name" : "path_value",
...
}
"header" : {
"header_name" : "header_value",
...
}
'querystring" : {
"querystring_name" : "querystring_value",
...
}
}
}
Copied from the Amazon API Gateway Developer Guide
For getting query parameters you get them in queryStringParameters object like this
const name = event.queryStringParameters.name;
The second one is a clean URL. If your path is /user/{name}, to get the value you get it from pathParameters object like this
const name = event.pathParameters.name;
Python 3.8 with boto3 v1.16v - 2020 December
For configuring routes, you have to configure API Gateway to accept routes. otherwise other than the base route everything else will end up in a {missing auth token} or something other...
Once you configured API Gateway to accept routes, make sure that you enabled lambda proxy, so that things will work better,
to access routes,
new_route = event['path'] # /{some_url}
to access query parameter
query_param = event['queryStringParameters'][{query_key}]
As #Jonathan's answer, after mark Use Lambda Proxy integration in Integration Request, in your source code you should implement as below format to by pass 502 Bad Gateway error.
NodeJS 8.10:
exports.handler = async (event, context, callback) => {
// TODO: You could get path, parameter, headers, body value from this
const { path, queryStringParameters, headers, body } = event;
const response = {
"statusCode": 200,
"headers": {
"Content-Type": "application/json"
},
"body": JSON.stringify({
path,
query: queryStringParameters,
headers,
body: JSON.parse(body)
}),
"isBase64Encoded": false
};
return response;
};
Don't forget deploy your resource at API Gateway before re-run your API.
Response JSON just return which set in body is correct.
So, you could get path, parameter, headers, body value from event
const { path, queryStringParameters, headers, body } = event;
The Lambda function expects JSON input, therefore parsing the query string is needed. The solution is to change the query string to JSON using the Mapping Template.I used it for C# .NET Core, so the expected input should be a JSON with "queryStringParameters" parameter. Follow these 4 steps below to achieve that:
Open the mapping template of your API Gateway resource and add new application/json content-tyap:
Copy the template below, which parses the query string into JSON, and paste it into the mapping template:
{
"queryStringParameters": {#foreach($key in $input.params().querystring.keySet())#if($foreach.index > 0),#end"$key":"$input.params().querystring.get($key)"#end}
}
In the API Gateway, call your Lambda function and add the following query string (for the example): param1=111¶m2=222¶m3=333
The mapping template should create the JSON output below, which is the input for your Lambda function.
{
"queryStringParameters": {"param3":"333","param1":"111","param2":"222"}
}
You're done. From this point, your Lambda function's logic can use the query string parameters.
Good luck!
exports.handler = async (event) => {
let query = event.queryStringParameters;
console.log(`id: ${query.id}`);
const response = {
statusCode: 200,
body: "Hi",
};
return response;
};
You can used Lambda as "Lambda Proxy Integration" ,ref this [https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-create-api-as-simple-proxy-for-lambda.html#api-gateway-proxy-integration-lambda-function-python] , options avalible to this lambda are
For Nodejs Lambda
'event.headers', 'event.pathParameters', 'event.body', 'event.stageVariables',
and 'event.requestContext'
For Python Lambda
event['headers']['parametername'] and so on
Refer Doc :
https://docs.aws.amazon.com/apigateway/latest/developerguide/integrating-api-with-aws-services-lambda.html#api-as-lambda-proxy-expose-get-method-with-path-parameters-to-call-lambda-function
You need to modify the Mapping Template
My goal was to pass a query string similar to:
protodb?sql=select * from protodb.prototab
to a Node.js 12 Lambda function via a URL from the API gateway. I tried a number of the ideas from the other answers but really wanted to do something in the most API gateway UI native way possible, so I came up with this that worked for me (as of the UI for API Gateway as of December 2020):
On the API Gateway console for a given API, under resources, select the get method. Then select its Integration Request and fill out the data for the lambda function at the top of the page.
Scroll to the bottom and open up the mapping templates section. Choose Request Body Passthrough when there are no templates defined (recommended).
Click on Add mapping templates and create one with the content-type of application/json and hit the check mark button.
For that mapping template, choose the Method Request passthrough on the drop down list for generate template which will fill the textbox under it with AWS' general way to pass everything.
Hit the save button.
Now when I tested it, I could not get the parameter to come through as event.sql under node JS in the Lambda function. It turns out that when the API gateway sends the URL sql query parameter to the Lambda function, it comes through for Node.js as:
var insql = event.params.querystring.sql;
So the trick that took some time for me was to use JSON.stringify to show the full event stack and then work my way down through the sections to be able to pull out the sql parameter from the query string.
So basically you can use the default passthrough functionality in the API gateway with the trick being how the parameters are passed when you are in the Lambda function.
The way that works for me is to
Go to Integration Request
click URL Query String Parameters
click Add query string
in name field put the query name, which is "name" here
in Mapped From field, put "method.request.querystring.name"
My 2 cents here: Lot of answers suggest to activate the option "Use Lambda Proxy Integration" and get the parameters from $.event.queryStringParameter or $.event.pathParameters. But if you happen to have Access-Control-Allow-Origin (a.k.a. CORS) activated, keep reading.
At the time of this post, Lambda Proxy integration and CORS don't work very well together. My approach was to deactivate the checkbox of Lambda Proxy integration and manually provide a Mapping templates for both request and response as follows:
Request template for application/json:
{
#set($params = $input.params().querystring)
"queryStringParameters" : {
#foreach($param in $params.keySet())
"$param" : "$util.escapeJavaScript($params.get($param))" #if($foreach.hasNext),#end
#end
},
#set($params = $input.params().path)
"pathParameters" : {
#foreach($param in $params.keySet())
"$param" : "$util.escapeJavaScript($params.get($param))" #if($foreach.hasNext),#end
#end
}
}
Mind that I named the properties as queryStringParameters and pathParameters on purpose, to mimic the names that Lambda Proxy integration would have generated. This way my lambdas won't break if one day I activate the Lambda Proxy integration.
Response template for application/json:
#set($payload = $util.parseJson($input.json('$')))
#set($context.responseOverride.status = $payload.statusCode)
$payload.body
How do you read these in your lambda (python)? (assuming parameters are optional)
def handler(event, context):
body = event["queryStringParameters"] or {}
result = myfunction(**body)
return {
"statusCode": code,
"headers": {
"content-type": "application/json",
},
"body": result
}
After reading several of these answers, I used a combination of several in Aug of 2018 to retrieve the query string params through lambda for python 3.6.
First, I went to API Gateway -> My API -> resources (on the left) -> Integration Request. Down at the bottom, select Mapping Templates then for content type enter application/json.
Next, select the Method Request Passthrough template that Amazon provides and select save and deploy your API.
Then in, lambda event['params'] is how you access all of your parameters. For query string: event['params']['querystring']