What is the best way to modify a data parameter in Angular 2?

Question

What is the best way to modify a data parameter in Angular 2?

I am facing an issue while trying to change a data parameter in my component file:

this.commandList.ListesCommandesATransmettre.forEach(data => {
    this.catalogs.forEach(catalog => {
        if (catalog.Libelle === data.Catalogue) {
            if (catalog.selected === false) {
                console.log(data.isSelected)
                data.isSelected = false;
                console.log(data.isSelected)
                console.log(data);
            }
        }
    })
});

Upon running this code, the following is displayed:

true
false

However, despite displaying false, when checking the value of isSelected using console.log(data), it still shows true. Can someone help me understand why?

arrays angular typescript parameters boolean

Answer 1

Answer №1

If you're experiencing a loop issue with the callback function, give this code a try

for (let item of this.commandList.ListesCommandesATransmettre) {
  for (let catalogItem of this.catalogs) {
    if (catalogItem.Libelle === item.Catalogue) {
      if (catalogItem.selected === false) {
        console.log(item.isSelected);
        item.isSelected = false;
        console.log(item.isSelected);
        console.log(item);
      }
    }
  }
}

Answer 2

If you're experiencing a loop issue with the callback function, give this code a try

for (let item of this.commandList.ListesCommandesATransmettre) {
  for (let catalogItem of this.catalogs) {
    if (catalogItem.Libelle === item.Catalogue) {
      if (catalogItem.selected === false) {
        console.log(item.isSelected);
        item.isSelected = false;
        console.log(item.isSelected);
        console.log(item);
      }
    }
  }
}

Answer 3

Answer №2

Your code logic seems a bit confusing to me. What if there are multiple catalogs in this.catalogs that meet the condition? The

isSelected</code> property might get set to false multiple times.</p>

<p>Perhaps a clearer approach could be:</p>

<pre><code>this.commandList.ListesCommandesATransmettre = this.commandList.ListesCommandesATransmettre.map(data => {
    const updatedData = Object.assign({}, data);

    // If the condition is met, set isSelected to false. Otherwise, keep its current value
    updatedData.isSelected = 
        this.catalogs.some(catalog => catalog.Libelle === data.Catalogue && !catalog.selected) ? false : updatedData.isSelected;

    return updatedData;
})

Answer 4

Your code logic seems a bit confusing to me. What if there are multiple catalogs in this.catalogs that meet the condition? The

isSelected</code> property might get set to false multiple times.</p>

<p>Perhaps a clearer approach could be:</p>

<pre><code>this.commandList.ListesCommandesATransmettre = this.commandList.ListesCommandesATransmettre.map(data => {
    const updatedData = Object.assign({}, data);

    // If the condition is met, set isSelected to false. Otherwise, keep its current value
    updatedData.isSelected = 
        this.catalogs.some(catalog => catalog.Libelle === data.Catalogue && !catalog.selected) ? false : updatedData.isSelected;

    return updatedData;
})

Answer 5

Answer №3

Give this code a try to check for proper updates. The loop will indicate which values are true or false, allowing you to verify the updated data.

this.commandList.ListesCommandesATransmettre.forEach((data, index) => {
    this.catalogs.forEach(catalog => {
        if (catalog.Libelle === data.Catalogue) {
            if (catalog.selected === false) {
                data.isSelected = false;
            }
            console.log(index + 'is selected: ' + data.isSelected)
        }
    })
});
console.log(this.commandlist);

I've observed that web browsers tend to retain only the 'most current' reference of an object in memory. Therefore, after a loop finishes, the last one to occur becomes the 'most current' reference. You might end up viewing the last object instead of the one you intend to test. If anyone has more knowledge or insights on what is actually happening, feel free to update this post.

Answer 6

Give this code a try to check for proper updates. The loop will indicate which values are true or false, allowing you to verify the updated data.

this.commandList.ListesCommandesATransmettre.forEach((data, index) => {
    this.catalogs.forEach(catalog => {
        if (catalog.Libelle === data.Catalogue) {
            if (catalog.selected === false) {
                data.isSelected = false;
            }
            console.log(index + 'is selected: ' + data.isSelected)
        }
    })
});
console.log(this.commandlist);

I've observed that web browsers tend to retain only the 'most current' reference of an object in memory. Therefore, after a loop finishes, the last one to occur becomes the 'most current' reference. You might end up viewing the last object instead of the one you intend to test. If anyone has more knowledge or insights on what is actually happening, feel free to update this post.

What is the best way to modify a data parameter in Angular 2?

Answer №1

Answer №2

Answer №3

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