How to correctly use axios params with arrays

Question

How to add indexes to array in query string?

I tried send data like this:

axios.get('/myController/myAction', { params: { storeIds: [1,2,3] })

And I got this url:

http://localhost/api/myController/myAction?storeIds[]=1&storeIds[]=2&storeIds[]=3

So, I should to get this url:

http://localhost/api/myController/myAction?storeIds[0]=1&storeIds[1]=2&storeIds[2]=3

What I should add in my params options to get this url?

Coexist

Just out of curiosity - wouldn't the url with [] still work? – Twilatwilight

Answer 1

You can use paramsSerializer and serialize parameters with https://www.npmjs.com/package/qs

axios.get('/myController/myAction', {
  params: {
    storeIds: [1,2,3]
  },
  paramsSerializer: params => {
    return qs.stringify(params)
  }
})

Primordial

Helped a lot... Was quite stuck trying to figure out how to build the params myself. – Hilliary

Me too :D Thank you so much! – Keenan

Even the axios documentation mentions the paramsSerializer just "by the way" – Keenan

Note that by doing it, params become a query. So to access it in the back-end, you would have to write req.query instead of req.params. At least that was the case for myself. – Iceland

It seems you can also use querystring Node module instead of qs, see #31757256 and github.com/axios/axios/issues/739 – Repartee

I got it to work using qs.stringify(params, { arrayFormat: "repeat" }) instead of just qs.stringify(params) This answer helped too: https://mcmap.net/q/175915/-multiple-fields-with-same-key-in-query-params-axios-request – Carmichael

qs.stringify(p, {arrayFormat: 'brackets'}) helps me – Weigle

Since 1.0.0 axios supports it natively, just set paramsSerializer.indexes to null. ref: github.com/axios/axios#request-config – Affirmation

Actually with recent versions, refer to the answer above using indexes property to control this with no need for external libs – Tracheostomy

Answer 2

Without having to add more libraries and using ES6 you could write:

axios.get(`/myController/myAction?${[1,2,3].map((n, index) => `storeIds[${index}]=${n}`).join('&')}`);

Fix

FYI, Axios is a library. github.com/axios/axios – Thesda

Oups! I meant MORE libraries. I corrected the answer, thanks! – Fix

I love this answer !. It's pure JS. No library required!. – Pede

to get this to work I did instead do .map((n, index) => storeIds[${index}]=${n}).join('&') otherwise since .map returns an array I have to do a join. Otherwise would get an unwanted ',' symbol between each value. – Strategy

@PerHyyrynen you are right! I'll correct the answer, thanks! – Fix

Answer 3

Thanks so much the answer from Nicu Criste, for my case, the API requires params like this:

params: {
  f: {
    key: 'abc',
    categories: ['a','b','c']
   },
  per_page: 10
}

Method is GET and this API requires the format is: API?f[key]=abc&f[categories][]=a&f[categories][]=b... So I assigned the paramsSerializer of axios like this:

config.paramsSerializer = p => {
      return qs.stringify(p, {arrayFormat: 'brackets'})
    }

• Install qs please go to this link
  
• Read more about paramsSerializer in axios document
• Edit format of params: Read more at qs stringifying document

Clabber

Answer 4

This behaviour has been added to axios starting with version 1.0.0. See paramsSerializer.indexes at https://github.com/axios/axios/tree/v1.0.0#request-config

Here's an example using your sample code:

axios.get('/myController/myAction', {
  params: { storeIds: [1,2,3] },
  paramsSerializer: {
    indexes: true, // use brackets with indexes
  }
)

The resulting query params will have indexes inside the brackets:

/myController/myAction?storeIds[0]=1&storeIds[1]=2&storeIds[2]=3

Other paramsSerializer.indexes values are null (no brackets):

axios.get('/myController/myAction', {
  params: { storeIds: [1,2,3] },
  paramsSerializer: {
    indexes: null, // no brackets at all
  }
)
// /myController/myAction?storeIds=1&storeIds=2&storeIds=3

And the default false (brackets without indexes):

axios.get('/myController/myAction', {
  params: { storeIds: [1,2,3] },
  paramsSerializer: {
    indexes: false, // brackets but no indexes
  }
)
// /myController/myAction?storeIds[]=1&storeIds[]=2&storeIds[]=3

Aeneus

Answer 5

In my case, I use ES6 array function. array element make querystring use reduce function. Object array also works.

const storeIds = [1,2,3]
axios.get('some url', {
  params: {
    storeIds: storeIds.reduce((f, s) => `${f},${s}`)
  }
})

Carlocarload

Your solution can be written a little shorter storeIds.join(',') – Headlock

Answer 6

There are a lot of good answers here. But I just wanted to share what I ended up using: (works like a charm even with other non-array parameters in your object)

Here is my params object:

params: {
    city: '335471',
    size: 4,
    page: 1,
    type: [1, 2, 3, 4, 5, 6],
}

This is the axios get method:

$axios.get('/some/api/endpoint/', {
    params,
    paramsSerializer: (params) => parseParams(params),
})

function parseParams(params) {
  const keys = Object.keys(params)
  let options = ''

  keys.forEach((key) => {
    const isParamTypeObject = typeof params[key] === 'object'
    const isParamTypeArray = isParamTypeObject && params[key].length >= 0

    if (!isParamTypeObject) {
      options += `${key}=${params[key]}&`
    }

    if (isParamTypeObject && isParamTypeArray) {
      params[key].forEach((element) => {
        options += `${key}=${element}&`
      })
    }
  })

  return options ? options.slice(0, -1) : options
}

And finally, using this method you will send this request:

https://yourwebsite.com/api/some/api/endpoint/?city=335471&size=4&page=1&type=1&type=2&type=3&type=4&type=5&type=6

source: https://github.com/axios/axios/issues/604#issuecomment-420135579

Heraldry

Answer 7

In my case, I am using someting like this

const params = array.map((v)=>{
            return `p=${v}&`
        })

Only concat params.join('') to the URL where you get data:

`url_to_get?${params.join('')`

In my back-end in ASP.net I receive this

[FromUri] string [] p

Linkage

Answer 8

I rewrote the existing paramSerializer shipped in axios. The following snippet does the same serialization while putting indices between square brackets. I tried qs but it is not compatible with my python connexion backend (for JSON string parameters).

const rcg = axios.create({
    baseURL: `${url}/api`,
    paramsSerializer: params => {
        const parts = [];

        const encode = val => {
            return encodeURIComponent(val).replace(/%3A/gi, ':')
                .replace(/%24/g, '$')
                .replace(/%2C/gi, ',')
                .replace(/%20/g, '+')
                .replace(/%5B/gi, '[')
                .replace(/%5D/gi, ']');
        }

        const convertPart = (key, val) => {
            if (val instanceof Date)
                val = val.toISOString()
            else if (val instanceof Object)
                val = JSON.stringify(val)

            parts.push(encode(key) + '=' + encode(val));
        }

        Object.entries(params).forEach(([key, val]) => {
            if (val === null || typeof val === 'undefined')
                return

            if (Array.isArray(val))
                val.forEach((v, i) => convertPart(`${key}[${i}]`, v))
            else
                convertPart(key, val)
        })

        return parts.join('&')
    }
});

Semibreve

Answer 9

This answer is inspired by @Nicu Criste's answer.

But might be not related to the posted question.

The following code was used to generate the query params with repetitive keys which had been supplied with an object array.

Note: If you are a developer with bundlephobia, use the following approach with care: as with UrlSearchParams support varies on different browsers and platforms.

const queryParams = [{key1: "value1"}, {key2: "value2"}]

axios.get('/myController/myAction', {
  params: queryParams,
  paramsSerializer: params => {
    return params.map((keyValuePair) => new URLSearchParams(keyValuePair)).join("&")
  }
})

// request -> /myController/myAction?key1=value1&key2=value2

Peregrination

Answer 10

you can create a function as parseParams that can send the params to this function and serialize it.

axios.get('/myController/myAction', {
  params: {
    storeIds: [1,2,3]
  },
 paramsSerializer: params => parseParams(params)
})

parseParams function is;

export const parseParams = (params) => {
  let options = '';

  for (const [key, value] of Object.entries(params)) {
    if (Array.isArray(value)) {
      for (const element of value) {
        options += `${key}=${element}&`;
      }
    } else {
      options += `${key}=${value}&`;
    }
  }

  return options.slice(0, -1);
};

Susa

Answer 11

I got using "paramSerializer" a bit confuse. Before looking for the "right way" to use axios with array querystring on Google, I did following and got working:

var options = {};
var params = {};
for(var x=0;x<Products.length;x++){
   params[`VariableName[${x}]`] = Products[x].Id;
}
options.params = params;

axios.get(`https://someUrl/`, options)...

It is going to create querystring parameters like:

VariableName[0]=XPTO,VariableName[1]=XPTO2

which the most webservers expected as array format

Gosnell

Answer 12

I know that this approach is not very good and I don't know the downsides it may have, but i tried this and it worked:

before making the request, prepare the params:

  let params = '?';

  for (let i = 0; i < YOUR_ARRAY.length; i++) {  // In this case YOUR_ARRAY == [1, 2, 3]
    params += `storeIds=${YOUR_ARRAY[i]}`;  // storeIds is your PARAM_NAME
    if (i !== YOUR_ARRAY.length - 1) params += '&';
  }

And then make the request like so:

axios.get('/myController/myAction' + params)

Glauconite

Answer 13

In React I needed to use axios with a params in array. This was query param:

"fields[0]=username&fields[1]=id&populate[photo][fields][0]=url&populate[job][fields][1]=Job"

to send with axios, for that I installed by CLI

npm install qs Read more about qs

and declared

const qs = require('qs');

after
const query = qs.stringify({
fields: ['username', 'id'],
populate: {
photo: {
fields: ['url']
},
job: {
fields: ['Job']
}
}
}, {
encodeValuesOnly: true
});

and finally I called the axios like this:
axios.create({
baseURL: "http://localhost:1337/api/",
}).get(`/users?${query}`) // this parameter show all data
.then((response) => console.log(response.data))
.catch((err) => {
setError(err);
});

Writing

Answer 14

Basically, reading from docs https://axios-http.com/docs/req_config
paramsSerializer is an optional function, which we should use if the default serialization of params done by axios is not as expected.

We can use serialization libraries (which I feel is best approach) to serialize in the params in the paramsSerializer function as per our needs.
Let's see an example.Suppose params is like ...

{
      params: {
        delay: 1,
        ar:[1,2,3]
      }
}

then you will get queryString like this ?delay=1&ar[]=1&ar[]=2&ar[]=3 when you make the request, but you might want like this ?delay=1&ar[0]=1&ar[1]=2&ar[2]=3

so in order to get query string as per our format. we can use qs https://www.npmjs.com/search?q=qs library
and serialize our params in the paramsSerializer function as below

{
      method: "GET",
      params: {
        delay: 1,
        ar:[1,2,3]
      },
      paramsSerializer: (params) => {
        return qs.stringify(params,{
          encodeValuesOnly: true
          });
      }
},

Senility

Answer 15

I had the issue that I wanted axios to omit brackets altogether. So I ended up with setting the paramsSerializer.indexes field to null. You can have the indices set as you want though by setting indexes to true.

axiosInstance.defaults.paramsSerializer = {
 
  // e.g. instead of
  // storeIds[]=1&storeIds[]=2&storeIds[]=3

  // you get
  // storeIds[0]=1&storeIds[1]=2&storeIds[2]=3

  // with
  indexes: true
};

It can also be set per request as it is part of the AxiosRequestConfig interface:

axios.get(
  '/myController/myAction',
  { 
    params: { 
      storeIds: [1,2,3] 
    }, 
    paramsSerializer: {
 
      indexes: true
    }
  }
)

Anticipation

Answer 16

I am working with nestjs and had to pass array in query, but it didnt successeded, I tried qs and paramsSerialization, but it didnt work. So I just join array with "," on one server and split it on another with ",". Fortunately, nestjs has @Transform, so it is easy to do.

array: array.join(',')

Code in dto:

@IsArray()
@IsString({ each: true })
@IsOptional()
@Transform(({ value }) => value.split(','))
  array: string[]; 

Infidelity

Answer 17

This work it for me:

axios.get("/financeiro/listar",{
        params: {
          periodo: this.filtro.periodo + "",
          mostrarApagados: this.filtro.mostrarApagados,
          mostrarPagos: this.filtro.mostrarPagos,
          categoria: this.filtro.categoria,
          conta: this.filtro.conta
        }
      })

Brutality

Answer 18

This was better for me:

axios.get('/myController/myAction', {
params: { storeIds: [1,2,3] + ''}

})

Imprecise

That will not give the desired result. – Irrelative

It does not give exactly the expected result, but it works – Imprecise

It does something but you can't say it works if it doesn't do what the OP needs it to do. – Irrelative

Also please note that a solution that does do what is needed was found over a year ago and currently has a score of 18. – Irrelative

It is true. But it's always good to try to offer some better solution. – Imprecise

But it isn't better. It's a comma-separated string, which standard form data parsers will not separate for you, and which won't handle data with commas in this (this particular example only has digits so that isn't a problem in this specific case). – Irrelative

That's why I clarified that it was the best in my case. That worked for me, I think others could do something similar according to need – Imprecise

I tried both solutions and this one is the only one that works for me. I use ids, It creates in the request the property params: id1,id2,id3 and it works!!! – Lanneret

If you have full control of the server side API you are communicating with: then this is a VERY neat/terse way to get your required data up (from the client) using axios and a get request. It does not create a query string as the OP asked for, but it IS very simple, neat and efficient way to do some of what the OP was asking for i.e. for a Get request, using Axios: how do I put my "array in query string". – Cuthburt

N.B. produces a url like : localhost/api/myController/myAction?storeIds=1,2,3 – Cuthburt

@Irrelative is right that most server side frameworks by default will not parse this correctly, but N.B. we are talking GET request here. i.e. may well not be "form data" (usually POST requests), and if you care about clarity and the number of bytes you're pushing up the wire this might be a good solution when coupled with some customisation on the server. – Cuthburt

Answer 19

In my case, there was already jQuery implemented into my codebase. So I just used the predefined method.

jQuery.param(Object)

Chalcidice