Angular read query string parameters

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In this video we will discuss, how to read query string parameters in Angular

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To read query parameters we use ActivatedRoute service. We use this same service to read required and optional route parameters.

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Inject the ActivatedRoute service using the component class constructor
constructor(private _route: ActivatedRoute) { }

Depending on your project requirements, you can then use either the snapshot approach or the observable approach. We discussed the difference between these 2 approaches and when to use one over the other in Part 42 of this Angular CRUD tutorial.

Part 42 - Subscribe to angular route parameter changes

In Angular there are 3 types of parameters.
1. Required parameters
2. Optional parameters
3. Query parameters

When working with any of these parameters, the following properties and methods are very useful.

Member Description

has(name) Returns true if the parameter is present and false if not. Very useful to check for the existence of optional route and query parameters

get(name) Returns the parameter value as a string if present, or null if not present in the map. Returns the first element if the parameter value is an array of values

getAll(name) Returns a string array of the parameter value if found, or an empty array if the parameter is not present in the map. Use getAll when a single parameter could have multiple values

keys Returns a string array of all the parameters in the map

Please note : For required and optional route parameters, we use the paramMap property of the ActivatedRoute object and for Query Parameters, we use queryParamMap property.

Use the snapshot approach if the query params does not change during the lifetime of this component.

} else {
}

On the other hand, if you expect the query parameter value to change during the life time of this component, and if you want to react and execute some code in response to that change, then use the Observable approach.

} else {
}
});
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I cannot thank you enough for this, this solved an issue that I was struggling with. Thank you!

alexmartini
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Hi Venkat (please respond) I truly feel in love with your SQL tutorial series, but I have a question-
I want to make Inner Join with 2 Tables and to use that join with other table again as Join between Table and Join. I'm not aware how I can do that via single query or else. All help is greatly appreciated, you are one of the best online tutors I have seen on youtube, well done keep it up.

DarkGT
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Sir your voice on my phone sounds different from my computer

noponyexpectstheequestrian
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hey, how do you get the id for manually created employee records?

muskaangupta
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please make it the same for angularJS to get the Param query case unreadable.
Help

edosirait
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no longer works if I use HttpClientModule in my app.module.ts. Any thoughts?

jamesleo
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hi sir can you tell me about file upload and upload file preview...

hp-quzi
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