My search form includes various filters such as text inputs, checkboxes, and radio buttons. Whenever the user interacts with these filters, the query string in the URL needs to be updated.
Consider the following scenario:
http://example.com/search?myFilter=1&myFilter=2&myFilter=3
This URL translates to an array: myFilter = ['1', '2', '3'].
The code snippet used to update the query string is as follows:
this.router.navigate([], {queryParams: myNewQueryString, relativeTo: this.routerActive});
Here, "this.router" refers to an instance of ActivatedRoute, and "myNewQueryString" represents the object containing the new query parameters. Essentially, this code updates the route by modifying the query string.
Prior to updating the query string with new filters, it's important to ensure that existing filters are not lost. To achieve this, I read the current query string using the following code:
const currentQueryString: any = this.routerActive.snapshot.queryParams;
While I can make changes to the query string based on this information, attempting to directly modify the properties of this object in Angular results in the error:
TypeError: Cannot assign to read only property 'parameter' of object
This error arises because the properties of:
this.routerActive.snapshot.queryParams
are all read-only, preventing direct modifications. Consequently, I need to create a new object and copy the properties like so:
const newQueryString: any = {};
for (const key in currentQueryString) {
if (currentQueryString.hasOwnProperty(key)) {
newQueryString[key] = currentQueryString[key];
}
}
By creating a duplicate of the current query string, I can manipulate it accordingly. However, when dealing with multiple values in an Array, the query string fails to update for all values, affecting only the first value.
Is this a bug in the system or is there a more effective approach to handle this situation?
The complete code snippet being utilized is shown below:
//query is an object like: { 'param' : 'value' }
updateQueryString(query: any): void {
const currentQueryString: any = this.routerActive.snapshot.queryParams;
const newQueryString: any = {};
//Copy the current query string
for (const key in currentQueryString) {
if (currentQueryString.hasOwnProperty(key)) {
newQueryString[key] = currentQueryString[key];
}
}
// Apply the new filter to the copied query string
for (const key in query) {
if (query.hasOwnProperty(key)) {
if (newQueryString[key] instanceof Array) {
newQueryString[key].push(query[key]);
} else {
const filter = [];
filter.push(query[key]);
newQueryString[key] = filter;
}
}
}
this.router.navigate([], {queryParams: newQueryString, relativeTo: this.routerActive});
this.search(newQueryString);
}
While additional validations may be necessary within this function, the focus at present is solely on updating the URL. Treating each parameter as an Array accounts for scenarios where multiple values need to be considered simultaneously.