I have a query that returns an array, with Object.key (array) .foreach I am iterating, I want to know the value of a property in specific array.
Example:
Object.keys(arreglo).forEach(function(key) {
console.log(arreglo[key]);
});
The output is:
name: "Pepito",
Surname: "Perez"
I want to know how to get only the value of the surname
I know it will not work but it would be something like:
console.log(arreglo[key].surname);
You can use Array.forEach on the original array as shown below. You can even extract the fields you are interested using Array.map.
// let's assume the arrary you got from your query is in this format
const arreglo = [
{ firstname: "fn1", surname: "ln1"},
{ firstname: "fn2", surname: "ln2"},
{ firstname: "fn3", surname: "ln3"}
];
// you can log `surname` for each entry in the array
arreglo.forEach(v => console.log(v.surname));
// you can use map to transform the array to just have `surname` using array.map()
const surnames = arreglo.map(v => v.surname);
console.log(surnames);
Is this what you are looking for
const object1 = {
a: {firstname:"sali",lastname:"mali"},
b: {firstname:"sali",lastname:"mali"},
c: {firstname:"sali",lastname:"mali"}
};
Object.keys(object1).forEach(function(key){console.log(object1[key].lastname)});
Related
What I was hoping to do was store an array of objects using RedisJSON very simply and then query that array.
I have something similar to this:
const data = [
{
_id: '63e7d1d85ad7e2f69df8ed6e',
artist: {
genre: 'rock',
},
},
{
_id: '63e7d1d85ad7e2f69df8ed6f',
artist: {
genre: 'metal',
},
},
{
_id: '63e7d1d85ad7e2f69df8ed6g',
artist: {
genre: 'rock',
},
},
]
then I can easily store and retrieve this:
await redisClient.json.set(cacheKey, '$', data)
await redisClient.json.get(cacheKey)
works great. but now I want to also query this data, I've tried creating an index as below:
await redisClient.ft.create(
`idx:gigs`,
{
'$.[0].artist.genre': {
type: SchemaFieldTypes.TEXT,
AS: 'genre',
},
},
{
ON: 'JSON',
PREFIX: 'GIGS',
}
)
and when I try and search this index what I expect is it to return the 2 documents with the correct search filter, but instead it always returns the entire array:
const searchResult = await redisClient.ft.search(`idx:gigs`, '#genre:(rock)')
produces:
{
total: 1,
documents: [
{ id: 'cacheKey', value: [Array] }
]
}
I can't quite work out at which level I'm getting this wrong, but any help would be greatly appreciated.
Is it possible to store an array of objects and then search the nested objects for nested values with RedisJSON?
The Search capability in Redis stack treats each key containing a JSON document as a separate search index entry. I think what you are doing is perhaps storing your whole array of documents in a single Redis key, which means any matches will return the document at that key which contains all of your data.
I would suggest that you store each object in your data array as its own key in Redis. Make sure that these will be indexed by using the GIGS prefix in the key name, for example GIGS:63e7d1d85ad7e2f69df8ed6e and GIGS:63e7d1d85ad7e2f69df8ed6f.
You'd want to change your index definition to account for each document being an object too so it would look something like this:
await redisClient.ft.create(
`idx:gigs`,
{
'$.artist.genre': {
type: SchemaFieldTypes.TEXT,
AS: 'genre',
},
},
{
ON: 'JSON',
PREFIX: 'GIGS:',
}
)
Note I also updated your PREFIX to be GIGS: not GIGS - this isn't strictly necessary, but does stop your index from accidentally looking at other keys in Redis whose name begins GIGS<whatever other characters>.
I have an object like this:
const querystring = require('querystring');
let data = {
name: 'Bill',
hobbies: ['Painting', 'Running']
}
If I encode the object like this:
console.log(querystring.encode(data));
I get this:
name=Bill&hobbies=Painting&hobbies=Running
Then when I decode it:
console.log(querystring.decode(querystring.encode(data));
It comes back perfectly like this:
{
name: 'Bill',
hobbies: ['Painting', 'Running']
}
However if I pass an object with array data that has only one item in it like this:
let data = {
name: 'Bill',
hobbies: ['Painting']
}
When I encode / decode it:
console.log(querystring.decode(querystring.encode(data));
This comes back:
{
name: 'Bill',
hobbies: 'Painting'
}
Notice how it converts the array to a single string, rather than an array with a single item.
Is there anyway around this limitation with querystring? Or is there another module that handles this better? I've been looking around and can't find anything.
I'm trying to update a column in users table the column type is json.
column name is test.
and the column consists of an object default value for example is
{a: "text", b: 0}
how to update let's say the object key b without changing the whole column
the code i'm using is
knexDb('users').where({
email: email
})
.update({
test: { b: 1 }
})
second solution
knexDb('users').where({
email: email
})
.update({
test: knexDb.raw(`jsonb_set(??, '{b}', ?)`, ['test', 1])
})
first solution changes the whole column cell and test will be only { b: 1 }
second solution doesn't work it give an error
function jsonb_set(json, unknown, unknown) does not exist
The expected result
is to manage to update only a certain key value in an object without changing the whole object.
PS
I also want to update an array that consists of objects like the above one for example.
[{a: "text", b: 0}, {c: "another-text", d: 0}]
if i use the code above in kenxjs it'll update the whole array to only {b: 1}
PS after searching a lot found that in order to make it work i need to set column type to jsonb, in order the above jsonb_set() to work
but now i'm facing another issue
how to update multiple keys using jsonb_set
knexDb('users').where({
email: email
})
.update({
test: knexDb.raw(`jsonb_set(??, '{b}', ?)`, ['test', 1]),
test: knexDb.raw(`jsonb_set(??, '{a}', ?)`, ['test', "another-text"]),
})
the first query key b is now not updating, in fact all updates don't work except the last query key a, so can some explain why ?
Your issue is that you're overwriting test. What you're passing into update is a JS object (docs). You cannot have multiple keys with identical values (docs). You'll have to do something like this where you make 1 long string with all your raw SQL as the value to test.
knexDb('users').where({
email: email
})
.update({
test: knexDb.raw(`
jsonb_set(??, '{a}', ?)
jsonb_set(??, '{b}', ?)
`,
['test', "another-text", 'test', 1])
})
Probably a better option exists - one that would be much more readable if you have to do this for several columns is something like what I have included below. In this example, the column containing the jsonb is called json.
const updateUser = async (email, a, b) => {
const user = await knexDb('users')
.where({ email })
.first();
user.json.a = a;
user.json.b = b;
const updatedUser = await knexDb('users')
.where({ email })
.update(user)
.returning('*');
return updatedUser;
}
Update/insert a single field in a JSON column:
knex('table')
.update( {
your_json_col: knex.jsonSet('your_json_col','$.field', 'new value')
})
.where(...)
Update/insert multiple fields
Option 1 (nested)
knex('table')
.update( {
your_json_col: knex.jsonSet(knex.jsonSet('your_json_col','$.field1', 'val1')
'$.field2', 'val2')
})
.where(...)
Option 2 (chained)
knex('table')
.update( {
your_json_col: knex.jsonSet('your_json_col','$.field1', 'val1')
})
.update( {
your_json_col: knex.jsonSet('your_json_col','$.field2', 'val2')
})
.where(...)
I have a schema like this
const user = new Schema({
firstName: { type: String, required: true },
lastName: { type: String , required: true},
phone:{type: Number, unique true}
embeddedDocsAsJson: {} // not as an array
},
{ minimize: false }
)
I want to use embeddedDocsAsJson because of two reasons
In case of array a duplicate data can be pushed to array , if I use json it will not occur as I'll use unique id as json key
Retrieval will be faster as I don't have to iterate on the array . I can fetch it from the json key
Problem:
Firstly I'm inserting firstName and lastName phone.
And embeddedDocsAsJson is added while updating the docs below is my code for updating
let user = await User.findOne({phone: somenumber})
user.embeddedDocsAsJson.someId = someObject // getting error in this line because `user.embeddedDocsAsJson` is `undefined`
user.save()
I'm adding value to embeddedDocsAsJson while updating
EmbeddedDocs are by-default array if you want to save object in your collection below code will work.
let user = await User.findOne({phone: somenumber})
user.embeddedDocsAsJson = {}
user.embeddedDocsAsJson.someId = someObject // getting error in this line because `user.embeddedDocsAsJson` is `undefined`
user.save()
I have an object array in a reducer that looks like this:
[
{id:1, name:Mark, email:mark#email.com},
{id:2, name:Paul, email:paul#gmail.com},
{id:3,name:sally, email:sally#email.com}
]
Below is my reducer. So far, I can add a new object to the currentPeople reducer via the following:
const INITIAL_STATE = { currentPeople:[]};
export default function(state = INITIAL_STATE, action) {
switch (action.type) {
case ADD_PERSON:
return {...state, currentPeople: [ ...state.currentPeople, action.payload]};
}
return state;
}
But here is where I'm stuck. Can I UPDATE a person via the reducer using lodash?
If I sent an action payload that looked like this:
{id:1, name:Eric, email:Eric#email.com}
Would I be able to replace the object with the id of 1 with the new fields?
Yes you can absolutely update an object in an array like you want to. And you don't need to change your data structure if you don't want to. You could add a case like this to your reducer:
case UPDATE_PERSON:
return {
...state,
currentPeople: state.currentPeople.map(person => {
if (person.id === action.payload.id) {
return action.payload;
}
return person;
}),
};
This can be be shortened as well, using implicit returns and a ternary:
case UPDATE_PERSON:
return {
...state,
currentPeople: state.currentPeople.map(person => (person.id === action.payload.id) ? action.payload : person),
};
Mihir's idea about mapping your data to an object with normalizr is certainly a possibility and technically it'd be faster to update the user with the reference instead of doing the loop (after initial mapping was done). But if you want to keep your data structure, this approach will work.
Also, mapping like this is just one of many ways to update the object, and requires browser support for Array.prototype.map(). You could use lodash indexOf() to find the index of the user you want (this is nice because it breaks the loop when it succeeds instead of just continuing as the .map would do), once you have the index you could overwrite the object directly using it's index. Make sure you don't mutate the redux state though, you'll need to be working on a clone if you want to assign like this: clonedArray[foundIndex] = action.payload;.
This is a good candidate for data normalization. You can effectively replace your data with the new one, if you normalize the data before storing it in your state tree.
This example is straight from Normalizr.
[{
id: 1,
title: 'Some Article',
author: {
id: 1,
name: 'Dan'
}
}, {
id: 2,
title: 'Other Article',
author: {
id: 1,
name: 'Dan'
}
}]
Can be normalized this way-
{
result: [1, 2],
entities: {
articles: {
1: {
id: 1,
title: 'Some Article',
author: 1
},
2: {
id: 2,
title: 'Other Article',
author: 1
}
},
users: {
1: {
id: 1,
name: 'Dan'
}
}
}
}
What's the advantage of normalization?
You get to extract the exact part of your state tree that you want.
For instance- You have an array of objects containing information about the articles. If you want to select a particular object from that array, you'll have to iterate through entire array. Worst case is that the desired object is not present in the array. To overcome this, we normalize the data.
To normalize the data, store the unique identifiers of each object in a separate array. Let's call that array as results.
result: [1, 2, 3 ..]
And transform the array of objects into an object with keys as the id(See the second snippet). Call that object as entities.
Ultimately, to access the object with id 1, simply do this- entities.articles["1"].
If you want to replace the old data with new data, you can do this-
entities.articles["1"] = newObj;
Use native splice method of array:
/*Find item index using lodash*/
var index = _.indexOf(currentPeople, _.find(currentPeople, {id: 1}));
/*Replace item at index using splice*/
arr.splice(index, 1, {id:1, name:'Mark', email:'mark#email.com'});