I am building out an Express API built with the mssql package.
If I don't call sql.close() then I get the following error:
Error: Global connection already exists. Call sql.close() first.
I'd like to keep the endpoints easy to follow and maintain and like the following pattern using a finally promise pattern.
const sql = require("mssql")
const config = require("../config")
sql.connect(config.properties).then(pool => {
return pool.request()
.execute('chain')
.then(response => {
res.send(response['recordsets'][0][0]['response'])
})
.catch(err => res.send(err))
.finally(sql.close())
})
However, this generates the following error:
{
"code": "ENOTOPEN",
"name": "ConnectionError"
}
The following code works, but it seems a bit clumsy to define sql.close multiple times in the same function.
sql.connect(config.properties).then(pool => {
return pool.request()
.execute('chain')
.then(response => {
res.send(response['recordsets'][0][0]['response'])
sql.close()
})
.catch(err => {
res.send(err)
sql.close()
})
})
Is there a way to call sql.close as part of the promise chain after either a response or error is sent with res.send?
.finally accepts function, you passing result of function
sql.connect(config.properties).then(pool => {
return pool.request()
.execute('chain')
.then(response => {
res.send(response['recordsets'][0][0]['response'])
})
.catch(err => res.send(err))
.finally(() => sql.close()) // FIX HERE
})
Related
I want to call this api multiple times in my project and when I am calling it , It continues giving an error which is
TypeError: Failed to execute 'json' on 'Response': body stream already
read at main.js:Line number
My Code is as Follows
let thisIsUrl = 'https://api.covid19api.com/summary';
let a = fetch(thisIsUrl)
a.then((data) => {
return data.json()
}).then((apidata) => {
console.log(apidata)
return apidata
}).catch((error) => {
console.log(error)
})
a.then((fetchdata) => {
return fetchdata.json()
}).then((readingData) => {
console.log(readingData)
}).catch((err) => {
console.log(err)
})
You're not calling fetch multiple times. You're calling it once, and then trying to read the response body multiple times. That's why the error says you're trying to read the body when the stream is already closed — it was closed when you were done reading it the first time.
If you want to use the data twice, store it somewhere and use it twice.
let thisIsUrl = 'https://api.covid19api.com/summary';
let a = fetch(thisIsUrl)
a.then((data) => {
return data.json()
}).then((apidata) => {
// **************** Use it twice here
}).catch((error) => {
console.log(error)
})
If you want to fetch it again because it may have been updated, call fetch again:
let thisIsUrl = 'https://api.covid19api.com/summary';
fetch(thisIsUrl)
.then((data) => {
return data.json();
}).then((apidata) => {
console.log(apidata);
return apidata;
}).catch((error) => {
console.log(error);
});
// Presumably this is later (in time), not immediately after the above
fetch(thisIsUrl)
.then((fetchdata) => {
return fetchdata.json();
}).then((readingData) => {
console.log(readingData);
}).catch((err) => {
console.log(err);
});
Finally, this seems unlikely, but if you really want to fetch it once and use that one result in multiple places via the promise chain, keep the promise from then rather than the promise from fetch:
let thisIsUrl = 'https://api.covid19api.com/summary';
let a = fetch(thisIsUrl)
.then((data) => {
return data.json()
});
a.then((apidata) => {
// ***** Use it here
}).catch((error) => {
console.log(error)
})
a.then((readingData) => {
// ***** And then again here
}).catch((err) => {
console.log(err);
});
Side note: Your code is falling prey to a footgun in the fetch API; I've written about it in this blog post. fetch only rejects its promise on network errors, not HTTP errors. You have to check for those yourself in the first fulfillment handler, by checking for ok on the response object:
fetch("/your/resource")
.then(response => {
if (!response.ok) {
throw new Error("HTTP error " + response.status); // Or better, use an Error subclass
}
return response.json();
})
// ...
fetch returns Promise, generally, promises have something like state inside themself;
pending: initial state, neither fulfilled nor rejected.
fulfilled: meaning that the operation was completed successfully.
rejected: meaning that the operation failed.
(source)
So when we call them and get the value from them with then, catch and etc. then they change the state after that call. So here, when you read the value with a.then(…, the promise changes its state to fulfilled and you are not able to call it again, you need a new and fresh Promise, actually a new instance of the fetch.
I want to recommend you to use Promise.all().
let thisIsUrl = 'https://api.covid19api.com/summary';
let a = fetch(thisIsUrl)
.then((data) => {
return data.json()
}).then((apidata) => {
console.log(apidata)
return apidata
}).catch((error) => {
console.log(error)
})
Promise.all([a,a,a]);
.then(results => {
// Results are here.
});
Hello I'm trying to test this API call but I don't know how to test for the status code of the response since it is a real (and it has to stay like that) API call and not a mock one
this is the function I'm testing:
export const getDataFromApi = (url) => {
return axios.get(url)
.then(({ data }) => data)
.catch(err => console.log(err.toString()));
}
and this is the test:
describe('Read data from API', () => {
test('Get result of the API call', (done) => {
const apiUrl = "https://rickandmortyapi.com/api/character";
getDataFromApi(apiUrl)
.then(data => {
expect(data).toBeDefined();
expect(data.results.length).toBeGreaterThan(0);
done();
});
});
});
how can I expect if the status code of data is 200 or if is another status code?
also is necessary for me to leave that done after the execution of the function? I know with call backs I have to put it but with this promise I'm not sure
Axios has a single response object returned in both the success and error paths which contains the HTTP status code. An error is raised if the response is not in the 2xx range.
You can plumb the status code as a return object from your getDataFromApi() wrapper function, but you'll probably want the full response object for other checks (like headers). I recommend getting rid of the wrapper altogether.
Without the wrapper, here's 2 different status checks using promises, one for success and one for failure:
describe('Read data from API', () => {
test('Get successful result of the API call', async() => {
const apiUrl = "https://rickandmortyapi.com/api/character";
await axios.get(apiUrl)
.then(r => {
expect(r.data).toBeDefined();
expect(r.data.results.length).toBeGreaterThan(0);
expect(r.status).toBeGreaterThanOrEqual(200);
expect(r.status).toBeLessThan(300);
})
.catch(e => {
fail(`Expected successful response`);
});
});
test('Get failure result of the API call', async() => {
const apiUrl = "https://rickandmortyapi.com/api/character-bad";
await axios.get(apiUrl)
.then(r => {
fail(`Expected failure response`);
})
.catch(e => {
if (e.response) {
expect(e.response.status).toBeGreaterThanOrEqual(400);
expect(e.response.status).toBeLessThan(500);
} else {
throw e;
}
});
});
});
I have successfully called a sequence of soap webservice methods using nodejs/javascript, but using callbacks... right now it looks something like this:
soap.createClient(wsdlUrl, function (err, soapClient) {
console.log("soap.createClient();");
if (err) {
console.log("error", err);
}
soapClient.method1(soaprequest1, function (err, result, raw, headers) {
if (err) {
console.log("Security_Authenticate error", err);
}
soapClient.method2(soaprequest2, function (err, result, raw, headers) {
if (err) {
console.log("Air_MultiAvailability error", err);
}
//etc...
});
});
});
I'm trying to get to something cleaner using Promise or async, similar to this (based on the example in the docs here https://www.npmjs.com/package/soap) :
var soap = require('soap');
soap.createClientAsync(wsdlURL)
.then((client) => {
return client.method1(soaprequest1);
})
.then((response) => {
return client.method2(soaprequest2);
});//... etc
My issue is that in the latter example, the soap client is no longer accessible after the first call and it typically returns a 'not defined' error...
is there a 'clean' way of carrying an object through this kind of chaining to be used/accessible in subsequent calls ?
Use async/await syntax.
const soap = require('soap');
(async () => {
const client = await soap.createClientAsync(wsdlURL);
cosnt response = await client.method1Async(soaprequest1);
await method2(soaprequest2);
})();
Pay attention to Async on both createClient and method1
In order to keep the chain of promises flat, you can assign the instance of soap to a variable in the outer scope:
let client = null;
soap.createClientAsync(wsdlURL)
.then((instance) => {
client = instance
})
.then(() => {
return client.method1(soaprequest2);
})
.then((response) => {
return client.method2(soaprequest2);
});
Another option would be nested chain method calls after the client is resolved:
soap.createClientAsync(wsdlURL)
.then((client) => {
Promise.resolve()
.then(() => {
return client.method1(soaprequest2);
})
.then((response) => {
return client.method2(soaprequest2);
});
})
I'm using blockexplorer API for blockchain, and I want to get block data based on specific hash (This hash should be taken from another function).
I'm new with using Promise, So can anyone help me to get the block data?
This is my code:
const be = require('blockexplorer');
be.block(be.blockIndex(0))
.then((result) => {
console.log(result)
})
.catch((err) => {
throw err
})
Also, I've tried another way with using nested Promise but it didn't work.
You can make a promise.then return a promise and chain it further. Modify the code to this.
be.blockIndex(0)
.then((result) => be.block(result))
.then((result) => {
console.log(result)
})
.catch((err) => {
console.log("Error Occurred: ", err); // Don't throw the error instead handle it
});
Basically I'm trying to fetch the URL and URLPaths for two images I've uploaded (to Firebase) using the firebase function /storeImage and JSON.Stringify().
Below is the snippet of code that enables me to fetch data for the ONE image.
.then(token => {
authToken = token;
return fetch("myappURL/storeImage",
{
method: "POST",
body: JSON.stringify({
image: image.base64
}),
headers: {
Authorization: "Bearer " + authToken,
}
});
})
.catch(err => {
console.log(err);
alert("Oops! Something went wrong, please try again1")
dispatch(uiStopLoading());
})
.then(res => {
if (res.ok) {
return res.json();
} else {
throw(new Error());
}
})
.then(parsedRes => {console.log(parsedRes);
Now I want to fetch data from a second image.
What I gather, from the docs I've read, is that I should use promises for multiple async calls like what I have above. So, shouldn't something like this (see below) work?
.then(token => {
authToken = token;
let image = fetch(... image: image.base64 ...);
let coverImage = fetch(... coverImage: coverImage.base64 ...);
Promise.all([image, coverImage])
.then(ress => { ress.forEach(
res => {
process( res.json() );
})
})
.catch(err => {...})
.then(res => {...})
.then(parsedRes => {console.log(parsedRes);)
Spoiler alert. I tried and it didn't. But I cannot understand why.
When you chain promises together, that is, start a new promise inside a then callback you need to return it.
Promise.all returns a single new promise that resolves when all of the promises passed to it resolve. In your code above you're neglecting to return it.
E.g. Try running this code which logs undefined
Promise.resolve()
.then(() => {
Promise.all([Promise.resolve(1), Promise.resolve(2)])
})
.then(result => console.log(result))
vs this code which logs [1, 2]
Promise.resolve()
.then(() => {
return Promise.all([Promise.resolve(1), Promise.resolve(2)])
})
.then(result => console.log(result))