At Codever we use Angular extensively, and many time the use navigates to certain routes where dynamically content based on an id for example is loaded. To access these path params in angular navigation you have two possibilities.

The first one, asynchronous, is to subscribe to the Observable<ParamMap> observable, which you can access via paramMap method of the ActivatedRoute. Then use the get method with parameter you want to get as argument, as in the example below in the ngOnInit method:

// other imports not included for brevity
import { ActivatedRoute } from '@angular/router';
import { switchMap } from 'rxjs/operators';

@Component({
  selector: 'app-public-snippet-details',
  templateUrl: './public-snippet-details.component.html'
})
export class PublicSnippetDetailsComponent implements OnInit {
  snippetId: string;
  snippet$: Observable<Codelet>;

  constructor(
    private publicSnippetsService: PublicSnippetsService,
    private userInfoStore: UserInfoStore,
    private route: ActivatedRoute) {
  }

  ngOnInit() {
    this.snippet$ = this.route.paramMap.pipe(
      switchMap(params => {
        this.snippetId = params.get('id');
        return this.publicSnippetsService.getPublicSnippetById(this.snippetId);
      })
    );
  }

}

The second one, synchronous, is to the snapshot of this route (ActivatedRoute), and directly access the parameter from the paramMap, const bookmarkId = this.route.snapshot.paramMap.get('id');

export class BookmarkDetailsComponent implements OnInit {
  // constructor and other details ignored for brevity

  ngOnInit() {
    this.popup = this.route.snapshot.queryParamMap.get('popup');
    this.userInfoStore.getUserInfo$().subscribe(userInfo => {
      this.userData$ = this.userDataStore.getUserData$();
      this.bookmark = window.history.state.bookmark;
      if (!window.history.state.bookmark) {
        const bookmarkId = this.route.snapshot.paramMap.get('id');
        this.personalBookmarksService.getPersonalBookmarkById(userInfo.sub, bookmarkId).subscribe((response) => {
          this.bookmark = response;
        });
      }
    });
  }
}

Reference - https://angular.io/guide/router


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When you are searching your code snippets on Codever, depending on the search terms you use, relevant results are displayed. Behind this there is a MongoDb full text search index. Let’s see how it is created and used.

Full text search is supported in Mongo by using a text index. Text indexes can include any field whose value is a string or an array of string elements, to which you can give weights. For a text index, the weight of an indexed field denotes the significance of the field relative to the other indexed fields in terms of the text search score.

db.snippets.createIndex(
  {
    title: "text",
    tags: "text",
    "codeSnippets.comment": "text",
    "codeSnippets.code": "text",
    sourceUrl: "text"
  },
  {
    weights: {
      title: 8,
      tags: 13,
      "codeSnippets.comment": 3,
      "codeSnippets.code": 1,
      sourceUrl: 1
    },
    name: "full_text_search",
    default_language: "none",
    language_override: "none"
  }
);

For each indexed field in the document, MongoDB multiplies the number of matches by the weight and sums the results. Using this sum, MongoDB then calculates the score for the document. You then can use the $meta operator for details on returning and sorting by text scores, as in the snippet below:

let getPublicBookmarksForSearchedTerms = async function (nonSpecialSearchTerms, page, limit, sort, specialSearchFilters, searchInclude) {

  let filter = {
    public: true
  }

  if ( nonSpecialSearchTerms.length > 0 ) {
    if(searchInclude === 'any') {
      filter.$text = {$search: nonSpecialSearchTerms.join(' ')}
    } else {
      filter.$text = {$search: bookmarksSearchHelper.generateFullSearchText(nonSpecialSearchTerms)};
    }
  }

  addSpecialSearchFiltersToMongoFilter(specialSearchFilters, filter);

  let sortBy = {};
  if ( sort === 'newest' ) {
    sortBy.createdAt = -1;
  } else {
    sortBy.score = {$meta: "textScore"}
  }

  let bookmarks = await Bookmark.find(
    filter,
    {
      score: {$meta: "textScore"}
    }
  )
    .sort(sortBy)
    .skip((page - 1) * limit)
    .limit(limit)
    .lean()
    .exec();

  return bookmarks;
}

Reference - https://docs.mongodb.com/manual/core/index-text/


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In Codever we use extensively the Angular Http Client to make REST calls against a NodeJs/ExpressJS API - source code on Github.

In the following snippet you can see hot to set http query parameters to the rest api calls.

Use the HttpParams class with the params request option to add URL query strings in your HttpRequest:

  getFilteredPersonalBookmarks(searchText: string, limit: number, page: number, userId: string, include: string): Observable<Bookmark[]> {
    const params = new HttpParams()
      .set('q', searchText)
      .set('page', page.toString())
      .set('limit', limit.toString())
      .set('include', include);
    return this.httpClient.get<Bookmark[]>(`${this.personalBookmarksApiBaseUrl}/${userId}/bookmarks`,
      {params: params})
      .pipe(shareReplay(1));
  }

Reference - https://angular.io/guide/http#url-params


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Use the nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS) on the mapping property you want to be checked. In this snippet you can see a PostalAdress entity is mapped to an entity of the same type, but the id is overwritten only when it is present in the source:

import java.time.LocalDateTime;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import org.mapstruct.NullValueCheckStrategy;

import com.example.entity.PostalAddress;

@Mapper(
    componentModel = "cdi",
    imports = {LocalDateTime.class})
public interface PostalAddressEntity2EntityMapperService {

  @Mapping(source = "id", target = "id", nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS)
  PostalAddress toPostalAddressntityToPostalAddressEntity(
      PostalAddress PostalAddress);
}

This will generate something similar with the following

package com.example.entitytoentity;

import com.example.entity.PostalAddress;
import java.time.LocalDateTime;
import javax.annotation.processing.Generated;
import javax.enterprise.context.ApplicationScoped;

@Generated(
    value = "org.mapstruct.ap.MappingProcessor",
    date = "2021-09-01T14:28:11+0200",
    comments = "version: 1.4.2.Final, compiler: javac, environment: Java 11.0.12 (Azul Systems, Inc.)"
)
@ApplicationScoped
public class PostalAddressEntity2EntityMapperServiceImpl implements PostalAddressEntity2EntityMapperService {

    @Override
    public PostalAddress toPostalAddressEntity(PostalAddress PostalAddress) {
        if ( PostalAddress == null ) {
            return null;
        }

        PostalAddress PostalAddress1 = new PostalAddress();

        if ( PostalAddress.getId() != null ) {
            PostalAddress1.setId( PostalAddress.getId() );
        }
        PostalAddress1.setStreeNo( PostalAddress.getStreetNo() );
        PostalAddress1.setStreet( PostalAddress.getStreet() );
        PostalAddress1.setMainAdress( PostalAddress.getMainAdress() );

        return PostalAddress1;
    }
}

Reference - https://mapstruct.org/documentation/stable/api/org/mapstruct/NullValueCheckStrategy.html


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A basic introduction in Rust, with code snippets taken from the The Rust Programming Language and Rust by Example books, to present in a 40 minutes slot.

You can execute most of the snippets directly on Rust Playground

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