I am getting the typeMismatch error when decoding JSON. Error states that it expects a Dictionary but found an array

Question

Created Dec ’20

Replies 4

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The full error is typeMismatch(Swift.Dictionary<Swift.String, Any>, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Dictionary<String, Any> but found an array instead.", underlyingError: nil))

I have tried both [QuoteData].self and QuoteData.self

Code Block func parseJSON(quoteData: Data) {
        let decoder = JSONDecoder()
        do {
            let decodedData = try decoder.decode(QuoteData.self, from: quoteData)
            //print(decodedData.zero[0].content)
            print(decodedData.zero[0].content)
        } catch {
            print(error)
        }
    }

Here is my struct

Code Block struct QuoteData: Decodable, Equatable {
    
    private enum CodingKeys : String , CodingKey { case zero = "0" }
    
    let zero : [Zero]
    
    
    struct Zero: Decodable, Equatable {
        let content : String
    }
}

This is the JSON I am requesting

Code Block [1 item
0: {
"content":"If you are out to describe the truth, leave elegance to the tailor."
"author":"Albert Einstein"
"category":"truth"
}
]

Code Block

Answered by OOPer in 652192022

This is what I got when I added that line.

Thanks. Text would always be better than image when showing JSON data.

With removing escaping characters and re-formatted, your JSON looks like this:

Code Block [
    {
        "content":"That's a great feeling to know that I'm going into a project that I have no idea what will become of that movie, but I really trust Ang Lee. And I really trusted Ron. It's just really nice to work with people that you feel that way about.",
        "url":"https://URL.. Connelly",
        "category":"trust"
    }
]

No 1 item, No 0:.

And what is the most important is that the outermost structure is JSON array indicated by [ and ].
You may need to pass an Array type to JSONDecoder.decode.

Something like this:

Code Block struct QuoteItem: Decodable, Equatable {
    let content: String
    //let url: URL
    //let category: String
}
func parseJSON(quoteData: Data) {
    //print(String(data: quoteData, encoding: .utf8) ?? "*")
    let decoder = JSONDecoder()
    do {
        let decodedData = try decoder.decode([QuoteItem].self, from: quoteData) //<- Pass an Array type
        //Here, `decodedData` is of type `[QuoteItem]`
        print(decodedData[0].content)
    } catch {
        print(error)
    }
}

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Answer 1

OOPer OP

Dec ’20

This is the JSON I am requesting

The data you have shown is not a JSON. Any JSON parser in the world cannot read it.

How have you got it?
In a local file of your project? Or is it some sort of debugging output?
Is it written in a spec of some API you are using?

The first thing you may need to do is clarifying the right data format.

Can you put this line before line 2 of parseJSON and tell us what you get?

Code Block     print(String(data: quoteData, encoding: .utf8) ?? "*")

0

Answer 2

andrew_holmes37 OP

Dec ’20

I didn't have a way to attach an image. This is what I got when I added that line.

Code Block Optional("[{\"content\":\"That\'s a great feeling to know that I\'m going into a project that I have no idea what will become of that movie, but I really trust Ang Lee. And I really trusted Ron. It\'s just really nice to work with people that you feel that way about.\",\"url\":\"https://URL.. Connelly\",\"category\":\"trust\"}]"

0

Answer 3

OOPer OP

Dec ’20

Accepted Answer

This is what I got when I added that line.

Thanks. Text would always be better than image when showing JSON data.

With removing escaping characters and re-formatted, your JSON looks like this:

Code Block [
    {
        "content":"That's a great feeling to know that I'm going into a project that I have no idea what will become of that movie, but I really trust Ang Lee. And I really trusted Ron. It's just really nice to work with people that you feel that way about.",
        "url":"https://URL.. Connelly",
        "category":"trust"
    }
]

No 1 item, No 0:.

And what is the most important is that the outermost structure is JSON array indicated by [ and ].
You may need to pass an Array type to JSONDecoder.decode.

Something like this:

Code Block struct QuoteItem: Decodable, Equatable {
    let content: String
    //let url: URL
    //let category: String
}
func parseJSON(quoteData: Data) {
    //print(String(data: quoteData, encoding: .utf8) ?? "*")
    let decoder = JSONDecoder()
    do {
        let decodedData = try decoder.decode([QuoteItem].self, from: quoteData) //<- Pass an Array type
        //Here, `decodedData` is of type `[QuoteItem]`
        print(decodedData[0].content)
    } catch {
        print(error)
    }
}

2

Answer 4

andrew_holmes37 OP

Dec ’20

Thanks that worked. Plus, that gave me some insight on how to view JSON data before i decode it.

0