Question

我还上传了the whole project to GitHub，代码和主要代码行，查询请求DetailFragment.java中的第144行。

我正在尝试使用id查询表中的成分，查询返回null结果。相同的查询运行良好但没有LIKE (:id) LIMIT 1，但是给出了所有行。

@Query("SELECT ingredients FROM recipe_db WHERE id LIKE (:id) LIMIT 1")
String getRecipeIngredients(List<Integer> id);

我试过了：

=代替LIKE
:ids没有()
单Integer/int id
如果所需的ID不存在，则检查数据库本身。

recipe_db代码

@Entity(tableName = DATABASE_NAME)
public class Recipe implements Parcelable {

@ColumnInfo(name = "image_url")
private String image;

@ColumnInfo(name = "servings")
private int servings;

@ColumnInfo(name = "steps")
private List<Steps> steps;

@ColumnInfo(name = "ingredients")
private List<Ingredient> ingredients;

@NonNull
@ColumnInfo(name = "name")
private String name;

@PrimaryKey
@ColumnInfo(name = "id")
private int id;

public Recipe(@NonNull String image, int servings, List<Steps> steps
        , List<Ingredient> ingredients, @NonNull String name, int id) {
    this.image = image;
    this.servings = servings;
    this.steps = steps;
    this.ingredients = ingredients;
    this.name = name;
    this.id = id;
}


public String getImage() {
    return image;
}

public int getServings() {
    return servings;
}

public List<Steps> getSteps() {
    return steps;
}

public List<Ingredient> getIngredients() {
    return ingredients;
}

public String getName() {
    return name;
}

public int getId() {
    return id;
}

public static class Steps {
    @SerializedName("thumbnailURL")
    private String thumbnailurl;
    @SerializedName("videoURL")
    private String videourl;
    @SerializedName("shortDescription")
    private String shortdescription;
    private String description;
    private int id;

    public String getThumbnailurl() {
        return thumbnailurl;
    }

    public String getVideourl() {
        return videourl;
    }

    public String getDescription() {
        return description;
    }

    public String getShortdescription() {
        return shortdescription;
    }

    public int getId() {
        return id;
    }

    public void setThumbnailurl(String thumbnailurl) {
        this.thumbnailurl = thumbnailurl;
    }

    public void setVideourl(String videourl) {
        this.videourl = videourl;
    }

    public void setShortdescription(String shortdescription) {
        this.shortdescription = shortdescription;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public void setId(int id) {
        this.id = id;
    }
}

public static class Ingredient {
    private String ingredient;
    private String measure;

    @Ignore
    private float quantity;

    private String str_quantity;

    public String getIngredient() {
        return ingredient;
    }

    public String getMeasure() {
        return measure;
    }

    public float getQuantity() {
        return quantity;
    }

    public void setIngredient(String ingredient) {
        this.ingredient = ingredient;
    }

    public void setMeasure(String measure) {
        this.measure = measure;
    }

    public void setQuantity(float quantity) {
        this.quantity = quantity;
    }

    public String getStr_quantity() {
        return String.valueOf(quantity);
    }

    public void setStr_quantity(String str_quantity) {
        this.str_quantity = str_quantity;
    }
}


@Override
public int describeContents() {
    return 0;
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    dest.writeString(this.image);
    dest.writeInt(this.servings);
    dest.writeList(this.steps);
    dest.writeList(this.ingredients);
    dest.writeString(this.name);
    dest.writeInt(this.id);
}

protected Recipe(Parcel in) {
    this.image = in.readString();
    this.servings = in.readInt();
    this.steps = new ArrayList<Steps>();
    in.readList(this.steps, Steps.class.getClassLoader());
    this.ingredients = new ArrayList<Ingredient>();
    in.readList(this.ingredients, Ingredient.class.getClassLoader());
    this.name = in.readString();
    this.id = in.readInt();
}

public static final Parcelable.Creator<Recipe> CREATOR = new Parcelable.Creator<Recipe>() {
    @Override
    public Recipe createFromParcel(Parcel source) {
        return new Recipe(source);
    }

    @Override
    public Recipe[] newArray(int size) {
        return new Recipe[size];
    }
};
}

Answer 1

尝试这种方式查询..

@Query("SELECT ingredients FROM recipe_db WHERE id LIKE :id LIMIT 1")
String getRecipeIngredients(List<Integer> id);

如果你想，那么试试名字和其他字段。

Answer 2

我已经在Android Nanodegree课程中问了我的导师“ ANTHONY”，这里是他的答案

发生这种情况是因为SQL设置不正确。

@Query（“从配方ID为WHERE id LIKE的ID中选择ID：ID LIMIT 1”）

您想要对其进行设置，使其与传入的ID相匹配。 LIKE子句   工作原理不同，并使用pattern matching symbols.

房间持久性库@Query无法正常工作

2 个答案: